Infection -MD2B3

Question 1

what are the 3 domains of public health?

Answer 1

health improvement
health protection
health and social care quality

Question 2

purpose of epidemiology

Answer 2

identify those at risk
assess effectiveness of interventions
determining importance of cause of illness

Question 3

what is the triad of causal factors?

Answer 3

agent
host
environment

Question 4

what is an epidemic/outbreak?

Answer 4

disease among specified population in excess of what’s expected in a given time and place

Question 5

what is a cluster?

Answer 5

group of cases in a specific time and place - more than expected

Question 6

what is an endemic?

Answer 6

disease or condition present among populations at all times e.g., malaria

Question 7

what is a pandemic?

Answer 7

a disease or condition that spread across regions e.g., coronavirus, HIV

Question 8

what is rate? and how is it calculated?

Answer 8

number of cases occurring during a specific period; dependant on size of population
number of cases/population at risk x 100

Question 9

define prevalence

Answer 9

how common is the disease? established and new cases included

(NEW & EXISTING)

Question 10

define incidence

Answer 10

rate at which new events occur over a defined period

NEW ONLY

Question 11

What is R0?

Answer 11

the average number of cases of an infectious disease arising by transmission from a single infected individual in a population which hasn’t previously encountered the disease

Question 12

how do you reduce infection spread

Answer 12

break the chain of infection

• infectious agents
• reservoirs
• portals of exit
• modes of transmission
• portals of entry
• susceptible hosts

Question 13

types of investigations in outbreak management

Answer 13

1. form outbreak control team (multidisciplinary team)
2. microbiological investigation (food samples, culture, sequencing, susceptibility testing)
3. environmental investigations (visit of premises, contaminated sites, observation practises, collection of samples)
4. traceback investigations (FSA, food traceability, ‘farm to fork’, rapid alert system)
5. veterinary investigations (Farm investigations, small animal practises)
6. entomological investigations (vector borne diseases, mosquitos, sand flies, ticks, map distribution of vectors)
7. gathering further information (identify info gaps, clinical details, lab results, trawling questionnaires)
8. immediate control measures (prophylaxis, exclusion/isolation, public warning, withdrew of products, closing establishments…)
9. communication (regular updates, keeping confidentiality, communicate public health messages, evaluate performance)

Question 14

features of bacteria

Answer 14

no membrane bound organelles
prokaryote
dna
PM
cytoplasm 
ribosomes

Question 15

name shapes of bacteria

Answer 15

cocci (spheres), bacilli (rods),

Question 16

what is a bacterial colony?

Answer 16

group of bacteria derived from the same mother cell - genetically identical

Question 17

describe bacteria by smell

Answer 17

bacteria produce different odours depending on the environment they’re in
electronic noses being developed to detect volatile substances

Question 18

give example of bacteria and the smells they produce

Answer 18

candida spp. = yeast
clostridium difficile = fecal, putrid
nocardia spp. = musty basement

Question 19

What bacteria have a purple appearance after staining?

Answer 19

gram positive

Question 20

what bacteria are a reddish colour after gram staining?

Answer 20

gram negative

Question 21

give an example of gram positive bacteria

Answer 21

staphylococci, streptococci and listeria

Question 22

give examples of gram negative bacteria

Answer 22

enterococci, salmonella, pseudomonas

Question 23

which gram bacteria have a thick peptidoglycan layer?

Answer 23

gram positive

Question 24

which gram bacteria have an outer lipid membrane? (+/-)

Answer 24

gram negative

Question 25

which gram bacteria have o-specific side chains present ? (+/-)

Answer 25

gram negative

Question 26

what is a unique feature of gram negative bacteria?

Answer 26

Lipopolysaccharides (LPS) antibiotics for example need to pass through this additional membrane before reaching targets inside cells therefore making them harder to treat. they also have prions which enable transport in and out

Question 27

what is a phototroph?

Answer 27

bacteria that utilise light as an energy source | e.g., cyanobacteria

Question 28

what is a chemotroph?

Answer 28

bacteria that can only gain energy from chemical compounds

Question 29

what do all bacteria require?

Answer 29

Carbon | and they all require CO2 in differing quantities

Question 30

what category of bacteria use CO2 as their major or sole source of carbon?

Answer 30

Autotrophic bacteria

Question 31

what category of bacteria use organic compounds as their carbon source?

Answer 31

heterotrophs

Question 32

name some causes and types of mutations

Answer 32

during DNA replication - efficiency of repair mechanisms silent, missense, nonsense, insertion/deletion exposure to mutagens - radiation, chemical agents

Question 33

what is the genome?

Answer 33

complete set of genetic material

Question 34

what is a genotype?

Answer 34

full collection of genes in the genome

Question 35

what is a phenotype?

Answer 35

observable characteristics and activities. defined by set of genes expressed at any one time

Question 36

what genes are always expressed?

Answer 36

constitutive

Question 37

What is the role of the promoter in gene regulation?

Answer 37

DNA sequence upstream of a gene where transcription machinery binds and initiates transcription

Question 38

What is the role of activators in gene regulation?

Answer 38

increase transcription of a gene - keep a gene on

Question 39

What is the role of repressors in gene regulation?

Answer 39

suppress transcription - keep a gene off

Question 40

What is the role of inducers in gene regulation?

Answer 40

small molecules that can either activate or repress transcription by binding to repressors or activators

Question 41

what is an operon?

Answer 41

sequence on the chromosome where structural proteins with related functions are usually encoded simultaneous control of genes that will either all be needed at the same time or none will be needed

Question 42

what is a regulon?

Answer 42

a group of several genes or operons that are turned on to off in response to the same signal by the same regulatory protein

Question 43

what is pathogenicity?

Answer 43

the capacity to initiate disease - qualitative - all or nothing

Question 44

what is virulence?

Answer 44

capacity to cause disease and severity of disease - quantifies pathogenicity

Question 45

what is transmissibility?

Answer 45

ability of pathogen to transmit from human to human or reservoir to human

Question 46

what are virulence factors?

Answer 46

proteins encoded by a bacterial organism that are essential for its pathogenicity - attribute the level of virulence

Question 47

What are the 4 criteria to assess whether a microorganism causes a disease (postulates)?

Answer 47

1. The microorganism is only found in the diseased individual 2. the microorganism must be cultured from the diseased individual 3. inoculation of the healthy individual with the cultured microorganism must cause the same disease 4. microorganism must be re-isolated from the inoculated, diseased individual and match the original organism

Question 48

what are the limitations of Koch's 4 postulates?

Answer 48

assumes pathogens are only found in diseased individuals and not healthy individuals not all pathogens can be grown in pure culture and not many human diseases can be reliably replicated in animal hosts so 3 and 4 can't be applied onset and severity of disease is dependant of the immune system of the host and their microbiome (postulate 3) Not ethically appropriate to test pathogen on humans

Question 49

steps to infection

Answer 49

transmission > adherence > invasion > survival in host > tissue damage

Question 50

Features of secretion systems

Answer 50

- key virulence factor to several bacteria - secrete molecules and virulence factors (effectors) out of bacteria cell to contact host - T1SS, T3SS, T4SS, T6SS, T7SS can transfer proteins directly from cytoplasm to bacterial cell - T2SS, T5SS, T8SS, T9SS can secrete proteins from the periplasm to the outside environment - T3SS, T4SS, T6SS deliver proteins directly into the cytoplasm of host cell using specialised pili

Question 51

which secretion systems are are specific to gram + bacteria?

Answer 51

T7SS

Question 52

which secretion systems are are specific to gram - bacteria?

Answer 52

T3SS, T6SS | T3SS are related to flagella

Question 53

stage 1 of infection

Answer 53

transmission exposure of host to pathogen usually reservoir

Question 54

name some routes of entry for transmission

Answer 54

respiratory - droplet/airborne GI - contaminated food, faecal - oral transmission mucous membranes - absorption through urinary or genital tracts, exposed eyes, nose, mouth skin - direct contact, open lesions, vector borne transmission

Question 55

the second stage of infection is adhesion | what does this entail?

Answer 55

process which organisms attach themselves to cells (colonisation) initial attachment is initiated by protein appendages - Fimbriae/pili/flagella further mediated through exopolysaccharides - change hydrophobicity of bacteria surface and displaces water to enhance hydrophobic interactions - closer contact a attachment can also occur through production of proteins and polysaccharides expressed on cell surface - creation of biofilms which are stabilised by glycolax - hard to remove

Question 56

describe the invasion step of infection

Answer 56

ECM creates physical stressors and host defence mechanisms against Bacteria pathogens therefore produce proteins that induce entry into non-phagocytic target cells...

Question 57

describe the zipper mechanism (invasion)

Answer 57

Bacteria express adhesins that bind with high affinity to host cell (interns, cadherins) Triggers host into attempting to bind with another cell - cell junctions formed and spread around bacteria bacterial cell is engulfed e.g., helicobacter pylori, listeria monocytogenes ZIPPER = ADHESINS AND CELL JUNCTIONS

Question 58

describe the trigger pathway (invasion)

Answer 58

Bacterial effector proteins injected directly into host cell cytoplasm using T3SS activates signalling pathway leading to large scale cytoskeletal rearrangement and ruffles formation membrane ruffles around bacteria and fold over, engulfing and internalising the bacteria e.g., salmonella, shigella TRIGGER = EFFECTORS & RUFFLES

Question 59

Survival in the host process (steps of infection)

Answer 59

vacuoles present hostile environment (low pH, nutrient deprived, target by host defences) to replicate they need to adapt lifestyles some escape from vesicle into cytoplasm where its more favourable (environmental cues) bacteria express and secrete uptake systems - siderophores for iron uptake evasion mechanisms - masking bacterial surface with host proteins (e.g., actin) ability to trigger F-actin on surface to provide mechanical force to propel them through cytosol into neighbouring cells Interfering with endosome maturation pathway - subvert host metabolism to modify membrane, present lysosomal fusion, import nutrients

Question 60

what are the three categories of pathogens relating to level of dependance on host

Answer 60

obligate facultative extracellular

Question 61

what are obligate pathogens?

Answer 61

require a host to fulfil their lifestyle - anaerobic bacteria (e.g.,chlamydia)

Question 62

what is a facultative intracellular pathogen?

Answer 62

host is only one of the niches they can exploit to reproduce e.g., salmonella and shigella

Question 63

what are extracellular pathogens?

Answer 63

thrive independently of a host cell e.g., S. aureus, E. coli

Question 64

what is the final stage of infection and what does it involve?

Answer 64

tissue damage In its effort to survive, replicate and find a new host, bacteria produce potent virulence factors that can cause tissue damage primary mechanism = toxin production toxins cause damage to host and can cause disease independent of bacterium

Question 65

what are the 2 main types of toxins?

Answer 65

exotoxins - secreted and present in both gram positive and negative bacteria endotoxins - Lipid A of lipopolysaccharides - Gram negative membrane

Question 66

Features of exotoxins

Answer 66

``` heat liable immunogenic can be enzymatic - potent types -neurotoxin - tetanus -enterotoxin - diarrhoea -cytotoxin - lyse host cells ``` AB subunit arrangements A: enzymatic activity B: binding to specific receptor and transferring across host cell membrane Enzymatic part not active until maturation of toxin - inactive while still in bacterium cell, active once secreted to avoid self damage A + B synthesised separately A - B synthesised separarlty but associated during secretion A/B synthesised together but inactive until cleaved pore forming toxins -insert pores into host cell membrane e.g., S. aureus superantigens - toxins that stimulate the immune system - act directly on T cells and antigen presenting cells - impair their function and lead to disease

Question 67

Features of endotoxins

Answer 67

toxic component of lipopolysaccharide (cell envelope, gram - bacterium) not a protein heat stable weakly antigenic - no vaccine not enzymatic - need high doses associated with endotoxic shock LPS degrades into O-antigen and Lipid A -Lipid A is pro-inflammatory and activates a cascade - loss of production control of host cell can lead to fever, or systemic shock and intravascular coagulation

Question 68

what is the natural history of a disease?

Answer 68

describes the expected progression of disease over time from first point of infection onwards (what symptoms in what order)

Question 69

what is the incubation period?

Answer 69

time between infection and symptom onset

Question 70

What is the latent period of a disease?

Answer 70

Time between person being infected and when they start being infectious

Question 71

what is the infectious period of a disease?

Answer 71

period of time a person is infectious

Question 72

three parts of descriptive epidemiology

Answer 72

Time - is the disease seasonal, pattern of disease changing over time? Place- does pattern of disease vary by place? Person - who is at risk, Age, occupation... who is more susceptible

Question 73

what are prevention strategies?

Answer 73

Primary - vaccination, limit salt intake, hand washing, healthy lifestyle Secondary - breast cancer screening, reduce risk of harm from disease, prompt treatment, early intervention Tertiary - prevent complications from the disease, diabetic eye screening, drugs to reduce risk of another stroke

Question 74

what is a case definition and why is it important?

Answer 74

important to have a clear definition of a case so their is consistency in the public health actions taken important for surveillance so you know you're counting the same disease in different areas might be based in different types of criteria -clinical criteria - signs and symptoms -microbiological criteria - lab tests -radiological criteria - x ray -epidemiological criteria - known link to confirmed case disease will have different definitions for possible, probable and confirmed cases - level of certainty will affect actions taken - balance benefits and harms and using resources - need a response proportionate to public health risk

Question 75

Bacteria of key public importance - Neisseria meningitides

Answer 75

``` gram negative aerobic diplococcal lives harmlessly in nose and throats of ~1 in 10 people can cause meningitis and septicaemia ``` Mode of transmission = person to person (kissing, household, close proximity) Natural History = incubation period of 3-5 days Clinical features = fever, cold hands and feet, vomiting, diarrhoea, difficult to wake, confusion Complications = 10% case fatality rate, permanent complications in ~15% of survivors Epidemiology Time - Meningococcal disease is seasonal - more common in winter Decrease in group c following vaccine -1999 place - higher incidence in belt spanning widest part of Africa person - overcrowding, smoking, recent flu, immune conditions, no spleen, 1-5 yrs or teenagers Prevention Primary - vaccination Secondary - rapid medical treatment, raise awareness of symptoms. Tertiary - antibiotics, intramuscular benzylpenicillin ``` Public health management notifiable disease check patient has been taken to hospital assess likelihood case is meningitis if conformed case contacts contacted case contacts tracked contacts offered chemoprophylaxis offered vaccine ```

Question 76

what is a cluster?

Answer 76

household cluster: 2 or more cases within 28 days within the same household. should be offered relevant vaccine sonf chemoprophylaxis residential/educational clusters: 2 or more cases within 28 days within an educational/residential setting

Question 77

Bacteria of key public importance- chlamydia trachomatis

Answer 77

``` Gram negative 3 biovars -thrachoma -chlamydia -lymphogranuloma venereum ``` causes chlamydia risk of neonatal conjunctivitis and pneumonia (child born to infected mothers) cause trachoma - eye infection leading to blindness chlamydia Mode of transmission = sexual - unprotected, sharing unwashed sex toys... = vertical - mother to baby at birth Natural History = incubation period - 1-3 weeks = often asymtomatic = 7 in 10 women and 5 in 10 men experience no symptoms clinical features = pain when urinating, unusual discharge = women - bleeding after sex, bleeding between periods = men - burning/itching urethra complications = fertility issues, ectopic pregnancy risk, men - sexually acquired reactive arthritis epidemiology time - detection fell in 2020, decline in test coverage, high volume of screening required, true prevalence in population will be higher, more testing = more cases place- detection rates in young people are higher in more deprived areas than least person - sexually active young people (under 25) most at risk, multiple partners with lack of condom use prevention primary- promote safe sex, condom use. no vaccines secondary - screening for asymptomatic individuals, raising awareness, reccomended getting tested once a year is sexually active with new partners tertiary - treatment with antibiotics, sex avoided until treatment has taken effect public health management not a notifiable disease contact tracing - advise partners to be tested.

Question 78

Bacteria of key public importance- Legionella pneumophila

Answer 78

gram negative bacterium rod shaped lives in water sources - infect humans when the infected water is aerosolised associated with legionnaires disease, can be fatal facultative intracellular bacterium mode of transmission = inhalation of bacteria via aerosols natural history = incubation period - 2-10 days before symptom onset (usually 6-7) no infection period as its not transmissible between humans clinical features = pneumonia, fever, dry cough, fatigue, head and muscle aches complications = case fatality rate of ~10% in Europe epidemiology time- seasonality, summer, early autumn, relate to weather patterns place- 2019, 48% of cases were community associated, 2% healthcare associated, 40% travel abroad, 10% uk travel Spain and UAE person - older age, male sex, recent travel, smoking, cv or respiratory disease prevention/treatment high quality water management biofilms protect pathogen but if broken up, it can travel with the water cooling towers are a risk as they spread the bacteria over a large distance. operate at ideal temperatures for pathogen to grow treatment - antibiotics, managing complications public health management of disease notifiable disease ascertain likely sources of infection and putting control measures in place source not person is focus of public management enhanced surveillance questionnaires too locate source

Question 79

Bacteria of key public health importance - Escherichia coli

Answer 79

gram- negative bacterium STEC and VTEC produce toxins that cause disease Reservoir is the digestive tract of ruminants - grazing animals with 4 part stomachs most well known STEC group is E. coli O157 - grouped based on O antigen can also be grouped based on H antigen - E. coli O157:H7 STEC causes GI illness and the E. coli can also cause bloodstream infections in vulnerable patients mode of transmission = food or water borne, or faecal oral transmission (animal or human) key risks - uncooked salad vegetables, uncooked meat, unpasteurised milk, water based activities, farm visits Natural History = incubation period of 3-4 days prolonged infectiousness through shedding of bacteria in stools clinical features = some may be asymptomatic or diarrhoea, abdominal cramps, vomiting complications = heamolytic uraemia syndrome - caused by STEC toxins killing RBCs. Makes patients anaemic and cause kidney issues and long term kidney damage, Gastroenteritis, high mortality rate(10%) epidemiology time - seasonal pattern - more cases over summer than winter place - northeast England has highest cases, London has the lowest person - young people most at risk. 58% of cases were female in 2018 prevention appropriate water management and treatment hand washing after contact with animals food hygiene measures free of symptoms for 48 hours before returning back to school treatment replacing fluids public health management strategies different actions depending on the certainty of diagnosis (possible, probable, confirmed) enhanced surveillance questionnaires - symtoms experienced, places travelled to , food outlets, water sources, contact with animals risk assessment for transmission outbreak management OCT investigations, finding source, surveillance, managing cases, control measures

Question 80

Bacteria of key public importance - clostridium difficile

Answer 80

``` gram positive + anaerobic rod shaped forms spores - allows survival in places cells can't lives in digestive tract produces disease causing toxins ``` Causes C.diff infection mode of transmission = faecal oral route, ingestion of spores natural history = lives inside people without causing any problems however when people are given antibiotics it can kill off other bacteria in the digestive tract and allow C. difficile to proliferate allowing the toxins to reach levels where they can cause disease clinical features = diarrhoea, fever, loss of appetite, nausea, abdominal pain complications = pseudomembranous colitis - 13.5% fatality rate 2019/20 Epidemiology Time - incidence and death rate has decreased dramatically since 2007 could be due to infection control interventions e.g., hand washing, guidance for antibiotic prescribing Place - contaminates environment due to pores. in a hospital it can quickly spread between vulnerable patients, Person - antibiotic use, old age Prevention good antibiotic prescribing practise infection control measures - isolate infected individuals, PPE, contractually NHS trusts have to keep infections below 10 Treatment antibiotics and supportive care to avoid dehydration public health management prevent person to person spread among vulnerable people SIGHT accronym S - suspect case is infectious where there is no other cause of diarrhoea I- isolate patient and consult with ICT G - gloves and aprons used for all contact with patients H - hand washing T - test stool for toxin

Question 81

Bacteria of key public importance - clostridium difficile

Answer 81

``` gram positive + anaerobic rod shaped forms spores - allows survival in places cells can't lives in digestive tract produces disease causing toxins ``` Causes C.diff infection mode of transmission = faecal oral route, ingestion of spores natural history = lives inside people without causing any problems however when people are given antibiotics it can kill off other bacteria in the digestive tract and allow C. difficile to proliferate allowing the toxins to reach levels where they can cause disease clinical features = diarrhoea, fever, loss of appetite, nausea, abdominal pain complications = pseudomembranous colitis - 13.5% fatality rate 2019/20 Epidemiology Time - incidence and death rate has decreased dramatically since 2007 could be due to infection control interventions e.g., hand washing, guidance for antibiotic prescribing Place - contaminates environment due to pores. in a hospital it can quickly spread between vulnerable patients, Person - antibiotic use, old age Prevention good antibiotic prescribing practise infection control measures - isolate infected individuals, PPE, contractually NHS trusts have to keep infections below 10 Treatment antibiotics and supportive care to avoid dehydration public health management prevent person to person spread among vulnerable people SIGHT acronym S - suspect case is infectious where there is no other cause of diarrhoea I- isolate patient and consult with ICT G - gloves and aprons used for all contact with patients H - hand washing T - test stool for toxin

Question 82

steps of an outbreak investigation

Answer 82

1. establish existence of a real outbreak 2. convene an outbreak control team 3. confirm diagnosis 4. define a case 5. search for cases / case finding 6. generate hypothesis - descriptive epidemiology 7. environmental, laboratory and other investigations 8. test hypothesis using analytical epidemiology 9. draw conclusions 10. communicate findings

Question 83

what is an outbreak?

Answer 83

single case for certain rare disease suspected, anticipated or actual event 2 or more people experiencing a similar illness and are linked in time and place greater than expected rate of infection

Question 84

what is an outbreak?

Answer 84

single case for certain rare disease suspected, anticipated or actual event 2 or more people experiencing a similar illness and are linked in time and place greater than expected rate of infection

Question 85

what are the aims of investigation by outbreak control team?

Answer 85

assess the risk to public agree and coordinate response with stakeholders describe the outbreak in terms of time, place and person generate and test the hypothesis identify the source/vehicle of infection implement control measures

Question 86

what are the main types of surveillance?

Answer 86

passive - you are notified stimulated passive - phone-calls / visits to facilities to trigger reporting active surveillance - search for records in healthcare facilities, door to door, potting possible cases

Question 87

what are features of a trawling questionnaire and what is it used for?

Answer 87

Used for generating a hypothesis includes - open ended questions - conducted by EHO's, health protection agency... - aims to identify - what is common to all cases, - symptoms and time of onset - events participated in - place visited - any outliers? - are they the source? problem with data collection?

Question 88

what is a line list used for?

Answer 88

collates cases in a systematic way and highlights time, place, person and lab results, allows generation of epidemic curve

Question 89

epidemiological curves

Answer 89

common source - intermittent or continuous point source - outbreak at defined point in time propagated source - person to person transmission

Question 90

what is a point source?

Answer 90

one common source, people ill at same time, one event e.g., wedding. one incubation period

Question 91

what is a continuous source?

Answer 91

source is not eradicated or controlled, single exposure over a long period

Question 92

what is a propagated source?

Answer 92

people infecting others, spread. | one case > incubation period > higher peak, then another group etc - secondary and tertiary cases

Question 93

what is an intermittent source?

Answer 93

periodic infection source is still coming through concurrent e.g., delivery of infected vegetables periodically all exposed to common source not well controlled so outbreaks reoccur

Question 94

when is a cohort study used?

Answer 94

in food outbreaks where population is known and available e.g., wedding reception allows attack rate and relative risk (RR) to be calculated

Question 95

when is a case control study used?

Answer 95

``` in large, exposed populations compares 'case' exposures or behaviours with controls odds ratio (OR) ```

Question 96

name some common control measures

Answer 96

1. remove the source - isolate and treat cases, destroy implicated foodstuffs from food chain 2. protect persons at risk - infection control, prophylaxis 3. prevent reoccurrence - local recommendations, national guidelines

Question 97

describe the innate response

Answer 97

``` fast directly detect an infectious agent through receptors/sesors genetically encoded memoryless no improvement over time ``` involves macrophages, dendritic cells and neutrophils (phagocytic cells) remove the microbe and destroy it

Question 98

describe the adaptive response

Answer 98

``` slower memory to previous encounters T cell and B cells somatic gene recombination capacity to recognise almost any pathogen ```

Question 99

what is the role of T cells in the adaptive immune response?

Answer 99

they initiate it help other immune cells - T helper cells kill infected cells by direct recognition - Cytotoxic T cells T cell interaction with peptide MHC is the molecular bridge between innate and adaptive response

Question 100

Name some epithelial barriers

Answer 100

skin epidermis bronchial ciliated epithelium, gut epithelium

Question 101

name some chemical barriers to infection

Answer 101

Lysozyme in tears and saliva surfactants in lungs stomach acid mucous in respiratory, GI and GU tracts

Question 102

what are pattern recognition receptors?

Answer 102

Proteins capable of recognising molecules frequently found in pathogens

Question 103

name some membrane bound Protein Recognition Receptors (PRRs)

Answer 103

Toll like receptors | C- type receptors

Question 104

what drives the expression of adhesion proteins on blood vessel cells?

Answer 104

inflammation

Question 105

What are lymphocyte antigen receptors?

Answer 105

use somatic gene recombination to create sequence diversity so almost limitless potential receptors can be encoded (T and B cell reeceptors) are not genetically encoded

Question 106

what is inflammation?

Answer 106

response to infection/injury of vascularised tissues. to eliminate dying cells and foreign bodies

Question 107

What is the set point of the immune system?

Answer 107

its crucial for healthy homeostasis | tolerance

Question 108

what happens during a bacterial infection?

Answer 108

subvert immune response or hijack it

Question 109

what is a PAMP?

Answer 109

pathogen associated molecular patterns

Question 110

what structures are found in/on stressed dying/dead host cells?

Answer 110

DAMPS | damage associated molecular patterns

Question 111

what is antigenic drift and why is it important?

Answer 111

its a point amino acid mutation in key proteins | its the driver of seasonal variation

Question 112

what is antigenic shift?

Answer 112

significant alteration in sequence often by capturing genetic sequences from closely related virus

Question 113

what allows viruses avoid immune evasion?

Answer 113

latency periods e.g., herpes virus. allows the virus to hide in the host genome and doesn't provide any antigens for presentation

Question 114

what is the virus that leads to AIDS?

Answer 114

human immunodeficiency virus 1 - lent virus

Question 115

how does chronic AIDS develop?

Answer 115

positive feedback from inflammation inability to clear self antigens broadening of immune response

Question 116

name some treatments for autoimmunity

Answer 116

costimulatory blockade - inhibits T cell activation (e.g., RA) corticosteroids immunosuppressants monoclonal antibodies

Question 117

what is a primary immune deficiency? - PID

Answer 117

born with a faulty immune system - congenital | results from genetic mutations

Question 118

is a secondary immune deficiency: congenital or acquired? (SID)

Answer 118

Acquired

Question 119

what is a SCID?

Answer 119

Severe combined immunodeficiency range of significant PIDS that cause defects in the adaptive immune response patients often come from consanguineous families (incest)

Question 120

what are potential origins of non self tumour antigens?

Answer 120

neoantigens formed by gene splicing aberrant expression of immune privileged antigens abnormal post translational modification to proteins that aid tumorgenesis oncoviral proteins

Question 121

what is CAR therapy?

Answer 121

inserts cancer targeting receptor Inyo T cells using lentiviral transduction ex vivo success in B cell acute leukaemia - 90% remission risk of cytokine storm and outgrowth of tumours

Question 122

when would a cohort study be used?

Answer 122

outbreak investigation in a well-defined population - able to identify full population potentially exposed cohort is a group of people with something in common

Question 123

what is attack rate?

Answer 123

proportion of people who become ill with a disease who were initially free number of cases/total number of participants x 100 calculate attack rates for exposed and unexposed individuals

Question 124

what is the risk ratio/relative risk?

Answer 124

ratio of exposed and unexposed attack rates

Question 125

what is relative risk?

Answer 125

risk of disease in exposed/risk of disease in unexposed this determines if the attack rate in the exposed is higher than the attack rate and by how many times

Question 126

what does it mean if the risk ratio is greater than 1

Answer 126

the agent in question is a risk factor (more exposed than unexposed were positive cases)

Question 127

what does it mean if the risk ratio is = to 1

Answer 127

no association between agent and disease

Question 128

what does it mean if the RR= less than 1

Answer 128

the agent in question is a protective factor against the disease

Question 129

when is a case control study used?

Answer 129

when there is not a defined population | e.g., an increase in cases in a particular geographical area

Question 130

are all cases included in a case control study?

Answer 130

yes and then controls are selected

Question 131

what is an odds ratio?

Answer 131

estimates the difference in frequency of exposure between cases and controls (from the same population) odds=probability an event will/will not happen

Question 132

what does it mean if the odds ratio is greater than 1

Answer 132

the agent is a risk factor (e.g., chicken) the higher the risk factor the stronger the association

Question 133

what does it mean when the odds ratio is equal to 1?

Answer 133

there is no association between the agent and the disease

Question 134

what does it mean when the odds ratio is less than 1

Answer 134

the agent is a protective factor

Question 135

what is a p-value?

Answer 135

probability of obtaining a result at least as extreme as the observed results assuming the null hypothesis is correct

Question 136

what is the null hypothesis?

Answer 136

no association between the cases and the exposure

Question 137

in what situation would we reject the null hypothesis?

Answer 137

if the p value is low (below 0.05/5%) we can say the association between factor and disease is likely to be real hence there is an association between cases and exposure and so the null hypothesis is rejected

Question 138

what does a p value below 0.05 indicate?

Answer 138

strong evidence against the null hypothesis | statistically significant association between the cases and exposure

Question 139

what are confidence intervals?

Answer 139

range of potential values for the RR or OR calculated from a sample a confidence interval indicates the precision with which the sample estimate is likely to represent the population from which that sample was drawn

Question 140

what does a 95% confidence interval mean?

Answer 140

for a 95% confidence interval the true value for the population at large will lie within the range 19 times out of 20 (95/100) a narrow CI implies a large sample size

Question 141

what does it mean if a confidence interval includes 1?

Answer 141

no evidence at the level of a p=0.05 that there is a true difference

Question 142

what is a confounder?

Answer 142

something that is associated with both the exposure and the outcome

Question 143

what is multivariable analysis?

Answer 143

looks at the the associations for several x variables (exposures) simultaneously but only 1 Y variable. is it the combination causing the disease?

Question 144

what is regression analysis?

Answer 144

set of statistical processes for estimating the relationships between a depending variable/outcome and one or more independent variables.

Question 145

what is an adjusted odds ratio?

Answer 145

controls for other variables - produces an odds for rich variable assuming the other variables were held constant

Question 146

how much do hospital acquired infections cost the NHS annually?

Answer 146

£1 billion | and 300000 patients

Question 147

what are features of S. aureus?

Answer 147

``` gram positive coccus staphylo clusters - grape like produce coagulase - blood clotting enzyme facultative anaerobe (w/without oxygen) ```

Question 148

what percentage of the population carry s. aureus?

Answer 148

30% - skin and nose in healthy individuals

Question 149

how does s.aureus cause infection?

Answer 149

adhesion invasion biofilm formation intracellular survival within cells

Question 150

describe the adhesion step of s.aureus infection

Answer 150

adhesion to the host epithelium or mucosal lining of the skin or nares. bacteria have several adhesins e.g., fibrinogen binding proteins, clumping factor A, which bind to host cell receptors

Question 151

describe the invasion step of s.aureus infection

Answer 151

when there is a breach in the epithelial layer s. aureus is able to penetrate to the lower layers of the tissue here the tissue resident macrophages and phagocytes such as neutrophils are recruited to the site of infection these phagocytose the bacteria and kill them. the local immune response leads to the formation of an abscess. however if the immune cells are not successful, the pathogen can invade deeper into tissues and eventually the blood stream

Question 152

describe the biofilm formation step of s.aureus infection

Answer 152

s. aureus can form biofilms on tissues and medical devices such as catheters antibiotics cannot penetrate biofilms efficiently and so are hard to treat effectively

Question 153

describe the intracellular survival of s.aureus within cells

Answer 153

its a facultative intracellular pathogen so can enter different types of host cells, including immune cells such as macrophages bacteria can replicate and then eventually lyse the cells to disseminate, or they can persist in this niche for longer times drugs cannot kill intracellular bacteria effectively

Question 154

name some infections caused by s.aureus

Answer 154

``` skin and soft tissue bone and joint - e.g., osteomyelinitis infective endocarditis pneumonia medical device or implant related q ```

Question 155

what drug is s. aureus resistant to?

Answer 155

beta-lactam - penicillin

Question 156

how many deaths were related to MRSA infection in the UK in 2018-19?

Answer 156

12878

Question 157

how does S. aureus become resistant to drugs?

Answer 157

modification of drugs target | enzymatic inactivation of the drug and active efflux of the drug

Question 158

what is endogenous spread of s. aureus?

Answer 158

when the patient is already colonised by the bacteria and it spreads to another part of the body

Question 159

what is exogenous spread of s. aureus?

Answer 159

from person to person | direct contact with skin, equipment or other surfaces

Question 160

name control measures hospitals use to prevent MRSA spread

Answer 160

hand hygiene general premises cleanliness covering wounds and lesions appropriate PPE

Question 161

what are the features of acinetobacter baumannii?

Answer 161

``` gram-negative rod shaped aerobic bacteria found in soil and water resistant to desiccation and dry conditions ```

Question 162

virulence mechanisms of A. baumannii

Answer 162

surface adhesions resistance to disinfection and desiccation it can pum disinfectant out of cell through efflux protein Ace-1 low alcohol concentrations can make it more virulent

Question 163

stats and facts about a. baumannii

Answer 163

causes 2% of HAIs globally infects the skin and mucous membranes major cause of infections in the army - survive in dry and sandy conditions cause pneumonia, blood stream infections, septicemia, UTIs

Question 164

what are the 4 mechanims of resistance of A.baumannii?

Answer 164

beta-lactam hydrolysis modification of aminoglycosides - inactivate antibiotics active efflux mechanisms - pump out antibiotics changing outer membrane - modify lipid A composition - deter binding

Question 165

what drug is used to treat a. baumannii infections

Answer 165

carbapenem antibiotic

Question 166

name theraputic options for a. baumannii treatment

Answer 166

polymyxins | tetrecyclines

Question 167

how old is the TB bacterium?

Answer 167

70000 years old

Question 168

what are risk factors for TB infection?

Answer 168

``` crowding HIV infection malnutrition diabetes alcohol use active smoking indoor pollution ```

Question 169

how is TB transmitted?

Answer 169

through aerosols not through contact or food

Question 170

what is the infection dose of TB?

Answer 170

very low: 3-10 bacilli

Question 171

what are the 4 stages of TB infection?

Answer 171

exposure latent - has TB but no symtoms active - signs and symptoms reactivation of latent infections

Question 172

what are the characteristics of the M. tuberculosis pathogen

Answer 172

``` gram positive long rods waxy outer membrane highly aerobic intracellular slow replication ```

Question 173

what is the outer waxy layer of the M. tuberculosis pathogen made of?

Answer 173

mycolic acids - long chain FAs hydrophobic membrane permeability barruer cell wall is key for virulence

Question 174

describe the pathogenic lifestyle of M. tb

Answer 174

bacterium enter lung through aerosols at alveolar surfaces, macrophages are recruited and the bacteria are internalised inside the macrophage, the bacteria replicate and this recruits other immune cells and further lymphocytes arrive at the site of infection and surround infected macrophages (granular maturation) granuloma start to die (granuloma necrosis) and the bacteria start replicating and taking over with extracellular replication transmission via breathing in out to another person

Question 175

How does M.tb survive within the host?

Answer 175

Primarily replicates and survives within macrophages | produces several proteins and enzymes that block macrophage processes to enable survival

Question 176

how does M. tb enter the macrophage?

Answer 176

enters through receptor-mediated endocytosis in a phagosome

Question 177

what happens once the M. tb is inside the macrophage?

Answer 177

blocks maturation of the phagosome prevents phagolysosomal formation and acidification induces cell death in macrophages Mtb then disseminates to infect other macrophages

Question 178

what are the symptoms of active lung TB?

Answer 178

``` cough with sputum and blood chest pains weakenss weight loss fever and night sweats ```

Question 179

what are the symptoms of extrapulmonary TB?

Answer 179

organ-specific | hard to diagnose early

Question 180

how is TB diagnosed?

Answer 180

Mantoux test - positive skin test or blood test only says whether someone has been infected or not chest x ray will show active disease bacterial culture from sputum rapid molecular diagnosis tests -high diagnostic accuracy PCR

Question 181

how is TB treated?

Answer 181

isoniazid rifampicin ethambutol treatment period is 6-9 months some drugs have several side effects

Question 182

is there a TB vaccine?

Answer 182

BCG- Bacille Calmette Guerin vaccine

Question 183

what was the most severe pandemic in history?

Answer 183

spanish flu 500 million infected 50 million deaths

Question 184

is the black death a zoonitic disease?

Answer 184

yes | transmits from animals to humans - bite or direct contact with infected tissues

Question 185

what is the fatality risk for the bubonic plague?

Answer 185

30-60%

Question 186

causes of emergence of pathogens with pandemic potential

Answer 186

``` global travel urbanisation climate change increased animal and human contact health worker shortages ```

Question 187

what is the aim of a pandemic response?

Answer 187

limit spread and contain/slow progression of epidemic ensure prompt and appropriate clinical care to reduce morbidity and mortality identify knowledge gaps and develop tools to prevent disease and improve treatment limit impact in terms of health, economic and social aspects of society

Question 188

what are the stages of an emergency response?

Answer 188

prevention preparedness response recovery continuous process

Question 189

what are the stages of a pandemic?

Answer 189

no known cases - focus on preparing, surveillance a few cases, small clusters - focus on containment, break transmission chains widespread community transmission - suppression and mitigation, reduce transmission

Question 190

strategies for response to COVID-19

Answer 190

containment suppression mitigation

Question 191

what are features of case-based interventions?

Answer 191

testing and contact tracing - detect and isolate cases, monitor close contacts, self isolation

Question 192

what are features of population based interventions

Answer 192

``` face masks social distancing closure of hospitality and entertainment work from home close schools ```

Question 193

what are features of border control measures

Answer 193

travel restrictions | mandatory quarantine

Question 194

what are the stages of vaccine development?

Answer 194

discovery phase 1 - given to a small group of healthy individuals for initial safety data phase 2 - determine safety effectiveness phase 3 - safety and effectiveness dose, side effects RCT regulatory - review and approval phase 4 - surveillance for adverse events, new formulations

Question 195

what is a drug used in covid treatment that was initially a malaria treatment

Answer 195

chloroquine consequently people with malaria who actually needed it suffered

Question 196

what are key features of public health surveillance?

Answer 196

``` ongoing systematic - collect same data - 'like for like' collation - from multiple sample points analysis - using appropriate methods interpretation dissemination ```

Question 197

what are the aims of surveillance?

Answer 197

1. assess public health status 2. evaluate public health programmes 3. inform research 4. define public health priorites

Question 198

what is the surveillance cycle?

Answer 198

1. data collection and collation 2. analysis and interpretation 3. dissemination of information

Question 199

what is indicator surveillance?

Answer 199

specific identity, could be pathogen specific

Question 200

what is event-based surveillance?

Answer 200

big outbreak

Question 201

What is passive surveillance?

Answer 201

being informed about cases

Question 202

What is active surveillance?

Answer 202

searching for cases | -case finding

Question 203

what is sentinal surveillance?

Answer 203

doesn't cover whole populations, only parts but its representitive

Question 204

what is comprehensive surveillance?

Answer 204

every case is identified - should know every measles case for example

Question 205

what is participatory surveillance?

Answer 205

invitation to take part e.g., surveys - TICK SURVEY

Question 206

what is syndromic surveillance?

Answer 206

cough for example

Question 207

Use influenza as an example for surveillance strategy

Answer 207

``` syndromic surveillance sentinal GP surveillance indictor based - hospital admissions or ICU admissions mortality lab reports ```

Question 208

what is the outcome of analysis?

Answer 208

reassurance allow NHS to plan services identification of increased local activity early warning of outbreaks

Question 209

what is the 'person' aspect of descriptive epidemiology?

Answer 209

count sick people define a case aids decision of who should be included in the surveillance system can be graded as suspect, probable, confirmed

Question 210

what is the 'place' aspect of descriptive epidemiology?

Answer 210

map | q

Question 211

what is the 'time' aspect of descriptive epidemiology?

Answer 211

analysis of data by time e.g., daily collection compare data on a day-by-day basis see trends, seasonality, fluctuations monitoring trends over time

Question 212

what are common failures in analysis?

Answer 212

person - failure to take into account population structures e.g., density, age, sex structure place - misclassification in terms of place of reporting time - misclassification in terms of date onset, date of diagnosis, date of reporting failuire to take step by step approach first aand produce approprite reccomendtions following analysis

Question 213

what is the rule for interpreting data?

Answer 213

``` should always treat an increase as real until proven otherwise but consider potential sources of error -changes in testing -delays in reporting -changes in reporting -impact of media reporting -completeness of data ```

Question 214

what is infectious disease modelling used for?

Answer 214

study the mechanisms by which diseases spread, predict future outbreaks and/or evaluate strategies to control/prevent disease spread make comparisons where clinical trials aren't available - alternative courses of action check generalisability of interventions

Question 215

name some common tyes of models

Answer 215

decision tree Markov model patient-level simulation

Question 216

what are decision trees used for?

Answer 216

compare interventions various consequences from 2 courses of action costs vs benefits

Question 217

what are the 3 health states of the markov model

Answer 217

progression free progression dead

Question 218

what is herd immunity?

Answer 218

direct protection experienced by unvaccinated individuals resulting from the presence of immune individuals in a population

Question 219

what must a model reflect?

Answer 219

natural history of the disease

Question 220

should models be complex?

Answer 220

models should be as simple as possible and no simpler

Question 221

what is a stochastic model?

Answer 221

allows the number of models who move through compartments to vary through chance - make assumptions

Question 222

what is a deterministic model?

Answer 222

describes what happens on average in a population- should be similar every time

Question 223

what is the force of infection?

Answer 223

- the rate at which susceptible individuals become infected per unit time - force of infection is the probability per unit time that a susceptible person acquires an infection - incidence of infection can be derived by multiplying the force of infection by the number of susceptible people

Question 224

what is R0?

Answer 224

'average number of secondary infectious persons resulting from one infectious person following introduction into a totally susceptible population' if R0 = 1 the incidence of disease in the population remains the same and doesn't change if R0= >1 the incidence of disease in the population will increase if R0=<1 the incidence of disease in the population will eventually disappear

Question 225

what is Rn

Answer 225

net reproduction number: average number of secondary infectious persons resulting from one infectious person in a given population the higher proportion that are immune the lower the probability the person becomes infected

Question 226

what is opportunity cost?

Answer 226

choices must be made competing uses of limited resources the benefit you give up due to not being able to spend money on more than one thing 1 heart bypass = 10 cateracacr removals = 300 flu vaccines

Question 227

how do you reduce the amount of agent released? | infection control in the workplace

Answer 227

treating cases to reduce the infectious period isolating cases eliminating/reducing environmental reservoirs

Question 228

what is a fomite?

Answer 228

any inanimate object that can carry and spread disease and infectious agents e.g., touch screens, rails, money, door handles

Question 229

what are the 6 steps in a chain of infection?

Answer 229

1. infectious agent 2. reserviour 3. portals of exit 4. mode of transmision 5. portal of entry 6. susceptible host

Question 230

what are common challenges to breaking the chain of infection?

Answer 230

``` high use of antimicrobial agents high prevalence of antimicrobial-resistant organisms high use of invasive devices/procedures patients who are frequently immobile patients who are undernourished ```

Question 231

what is source isolation (standard)

Answer 231

isolation in a side room, usually with en-suite

Question 232

what is protective isolation?

Answer 232

patients who are severely immunocompromised through illness are particularly susceptible to infection and may require specialist protective isolation

Question 233

what is negative pressure isolation?

Answer 233

prevents contaminated air mixing with clean air - ventilation system to outside not in the building.

Question 234

what is strict isolation?

Answer 234

rare infectious diseases designated high level isolation unit negative pressure room

Question 235

what is cohort nursing?

Answer 235

happens when there aren't enough rooms to isolate patients either cohorted with the same organism e.g., MRSA or if they have the same symtoms e.g., diarrhoea should be cared for by designated staff in designated bay or ward

Question 236

how much do facemasks reduce transmission by?

Answer 236

53% (Tara et al, 2021)

Question 237

what is the prevention paradox in relation to face masks?

Answer 237

an intervention that brings moderate benefits to individuals but large population benefits

Question 238

collectivism vs individualism related to face masks

Answer 238

in east asia, face coverings were widely used pre-pandemic (normative practise) could be due to past experience with respiratory virus or a civic mindset (interdependence over independence) or air pollution

Question 239

what is individualism in relation to facemasks?

Answer 239

individualism refers to the dominant values in a society where people are loosely connected to each other and where the expectation is to look after oneself only and immediate family

Question 240

individualism vs collectivism- what is better when it comes to a health crisis?

Answer 240

collectivist values led to specific health-related behaviours that ultimately reduced transmission rate and kept more people alive collectivist cultures responded quicker to health crisis

Question 241

what is the optimism bias?

Answer 241

human brain believes that our chances of experiencing negative events are lower and are chances of experiencing positive events are higher than our peers - illusion of invulnerability can lead to poor decision making with sometimes harmful consequences - not wearing suncream, not wearing seatbelts can be positive - self-esteem, lower stress

Question 242

what is psychological reactance?

Answer 242

unpleasant arousal when an individual is asked to follow orders that they believe infringe on their personal choices and autonomy men are more likely to argue it infringes on their freedom women are more likely to claim its uncomfortable as a reason for non-compliance mask-wearing seen as breach of personal freedom

Question 243

what is haemogenic masculinity?

Answer 243

this is the ideal concept of being a man domiant masculinity can exert a social power and dominance over other masculinities (effeminate, gay, introverted) and women as people are socialised to to value those aspects of men face covers may be seen as a threat to masculinity, symbol of subversivience or weakness - toxic masculinity

Question 244

Who is more susceptible to misinformation?

Answer 244

low health literacy

Question 245

how does anti-intellectualism affect facemask adherence?

Answer 245

there is a generalised distrust of experts and intellectuals people tend to be persuaded by speakers when they perceive them as knowledgeable and if they share a common interest less amenable to expert messages as a result even in a time of crisis individuals who scored higher for anti-intellectualism were significantly less likely to obtain COVID-19 information and guidance

Question 246

describe how conspiracy theories affect face mask-wearing in relation to the social cognition model

Answer 246

this theory predicts behaviour outcome expectations conspiracy theories can diminish pro face cover wearing outcome expectations and therefore reduce uptake of the behaviour

Question 247

describe how conspiracy theories affect face mask-wearing in relation to the theory of planned behavior

Answer 247

conspiracy theories can negatively affect attitudes towards wearing facemasks in people who believe them making them less likely to enact the behaviour some people wearing masks have faced alienation or discrimination which reduces their perceived control which reduces likelihood of behaviour if mask uptake is low its likely to be deemed as a subjective norm which further reduces behaviour likelihood

Question 248

Who invented the vaccine 1796?

Answer 248

Edward Jenner

Question 249

what is a vaccine?

Answer 249

mimic a pathogen and stimulate a protective immune response stimulate immune memory which allows the body to be prepared to fight off infection next time the body is challenged/attacked by a pathogen memory T snd B cells reside in germinal centres, lymphatic system including spleen and bone marrow

Question 250

what is the role of B cells in vaccines and immunity?

Answer 250

b cells are triggered by vaccine > plasma cells > memory B cells

Question 251

what is a prophylactic?

Answer 251

preventative measures e. g., a vaccine they prepare the immune system to defend the body against infection e. g., beta-blockers prevent heart attacks e. g., birth control to prevent pregnancy

Question 252

what is a herd immunity threshold?

Answer 252

the level of immunity required within a population that stops the spread of the virus its pathogen-specific e.g., small pox - 80-85% measles - 93-95%

Question 253

what is the R0 number for SARS-CoV-2?

Answer 253

2-3 | if an infected individual encounters 10 other people , on average, 2 of them will become infected

Question 254

what is the basic composition of a vaccine?

Answer 254

1. a vector or platform - a delivery system e.g., adenoviral vectors 2. antigen or vaccine target - part of the virus or bacteria that produce an immune response (3. sometimes an adjuvant is added that helps mimic the inflammatory effects of infection, producing a better immune response)

Question 255

what are the features of the influenza vaccine?

Answer 255

negative RNA strand virus 8 segments H1 and H3 influenza subtypes, in addition to 2 influenza B lineages circulate in the human population heamagglutinin (HA) is the major surface antigen in influenza.

Question 256

how many deaths and cases of influenza are there each year?

Answer 256

between 200000 to 600000 deaths each year | between 1 to 4 million severe cases per year

Question 257

describe the influenza vaccine components?

Answer 257

trivalent and quadrivalent vaccines consist of one strain of H1N1 influenza A and one strain of H3N2 influenza A as well as one strand of influenza B

Question 258

what is the protectiveness of the flu vaccine?

Answer 258

33% of individuals who receive it get protection reformulated every 3 years

Question 259

describe features of the SARS-CoV-2

Answer 259

positive single stranded virus major antigen is the spike protein genome encodes 16 proteins binds to ACE2 receptor endocytosis is triggered and fusion occurs genome is released in an environ and duplicates zoonotic reserviour

Question 260

what are the methods for creating covid vaccines?

Answer 260

target spike proteins replication-competent vaccines - display spike proteins - expensive, difficult inactivated virus vector vaccines - display spike proteins - expensive, difficult DNA vaccines - plasmid - quick, cheap RNA vaccines - quick and cheap

Question 261

how many deaths does immunisation prevent every year?

Answer 261

2-3 million deaths every year

Question 262

what is vaccine hesitancy?

Answer 262

a delay in acceptance or refusal of vaccination despite the availability of vaccination services - its a continuum range of attitudes towards vaccines

Question 263

what is the 3C's model?

Answer 263

complacency confidence convenience

Question 264

describe the complacency aspect of the 3 C's model in relation to vaccine hesitancy

Answer 264

low health literacy misunderstanding of vaccine importance subscribing to conspiracy theory belief that natural immunity or natural foods are sufficient for infection prevention

Question 265

describe the confidence aspect of the 3 C's model in relation to vaccine hesitancy

Answer 265

scepticism about vaccine effectiveness and true purpose distrust in authorities subscribing to conspiracy theories that vaccine is unsafe/has side effects lower vaccination rates among minority groups due to lower levels of trust/confidence - historical abuse

Question 266

describe the convenience aspect of the 3 C's model in relation to vaccine hesitancy

Answer 266

not being eligible for a vaccine at a particular time point e.g., only certain age groups invited living in a country with limited vaccine availability individuals may be unable to afford cost of vaccination

Question 267

what is omission bias?

Answer 267

tendency to react more strongly to harmful actions than to harmful inactions

Question 268

how do we reduce vaccine hesitancy?

Answer 268

concerns need to be addressed and dealt with empathy 1/3 claimed it was easier if administered by a doctor people need standardised, accurate and informative resources to empower people to make the right choices for themselves

Question 269

what is a fear appeal - vaccination uptake

Answer 269

persuasive messages that attempt to arouse fear by emphasising potential danger research shows that threats or coercion is not always effective at changing attitudes or internal motivation towards a behaviour

Question 270

what is the tri risk model and how is it used to explain vaccination uptake?

Answer 270

1. risk belief and anticipated regret about infectious diseases correlate reliably with whether individuals get vaccinated or not 2. social processes can motivate getting vaccinated - humans are generally influenced by perceived normative behaviour 3. affective risk - worry, fear, anxiety can spur people to get vaccinated

Question 271

what a sort of messages proved successful to promote vaccination?

Answer 271

those that included personal benefit reduced vaccine hesitancy in those that were strongly hesitant those that are strongly hesitant are more likely to feel excluded from wider public for their views so don't respond well to collective benefit messages

Question 272

what is health inequity?

Answer 272

differences in health status or in the distribution of health resources between different population groups arising from the different social conditions in which people are born, grow, live work and age

Question 273

what are the 2 urgent interests in a pandemic in the global community?

Answer 273

1. lifesaving vaccines be created, manufactured and distributed 2. the disease be quickly contained and eliminated worldwide

Question 274

what role do pharmaceutical companies have in vaccine inequity?

Answer 274

they have financial interests - product usually goes to the highest bidde rather than where there is the greatest need disproportionate distribution happens as a result

Question 275

what are the statistics of vaccine distribution globally?

Answer 275

wealthy countries with 14% of the world's population bought 53% of the most promising vaccines - hoarding

Question 276

how many deaths could have been avoided if vaccines were distributed fairly?

Answer 276

61% of deaths if vaccines had been distributed to all countries proportional to the population

Question 277

what is COVAX?

Answer 277

covid 19 vaccine global access facility aimed to contribute to equitable distribution of the covid vaccines worldwide vaccines delivered as soon as available high-income countries, companies and philanthropic organisations would cover the cost for 92 of the poorest countries.

Question 278

what are 6 things we knew about covid but didn't realise we did?

Answer 278

1. we knew covid was coming - good to properly be prepared 2. most people will be okay over time 3. the poor and vulnerable are liable not only to disease but also poor mental health 4. culture matters too, in terms of myths and other beliefs 5. politics goes alongside trust, particularly when being aksed to try something new 6. in challenging times, resources are important for relationships

Question 279

what proportion of people wear masks to protect themselves?

Answer 279

96%

Question 280

what proportion of people get vaccinated to protect themselves?

Answer 280

84%

Question 281

what is a natural product in terms of chemistry/drug development?

Answer 281

a chemical compound that has been made by a living thing secondary metabolite - not strictly essential for organisms survival any product made by a living organisms e.g., plant extracts, honey, bile

Question 282

what is a stigmasterol?

Answer 282

it is used as a precursor for lots of human hormones e.g., ostrogen, progesterones, testossterone used for emergency contraceptives, HRT, breast cancer, hypogonadism

Question 283

what natural product is now used in chemotherapy?

Answer 283

pacific yew tree bark - chemically fractioned and used to kill cancer cells - blocks mitosis

Question 284

what is ethnopharmacology?

Answer 284

study of substances of traditional/folk medicines look at historical medicines instead of trying to discover new ones

Question 285

What makes it difficult to know if promising antibiotics in the lab are transferrable to humans?

Answer 285

bacteria make biofilms so bacteria grow differently in humans than on. a petri dish

Question 286

what is the pathway for testing if drugs are safe?

Answer 286

start with cell lines - cheap & easy but overestimates damage en vivo organ - a collection of structured differentiated cells live animal model - more realistic see systemic effects, very expensive, ethical concerns, licence needed human phase 0 trial - low dose on healthy people

Question 287

what is the 3 rule when it comes to testing?

Answer 287

Reduce Define Replace cows eyes are often used in cosmetic testing, take from slaughter house, animal is already dead

Question 288

how do we isolate the molecules bacteria produce to analyse them?

Answer 288

analytical chemistry separation sciences - chromatography structural characterisation - NMR, Mass spectroscopy

Question 289

what is mortality?

Answer 289

number of deaths

Question 290

what is morbidity?

Answer 290

DALYs | years life lost due to premature mortality and years lived with a disability (YLD)

Question 291

In 2016 how many people were infected with an NTD?

Answer 291

~1 billion

Question 292

how much funding do neglected tropical diseases get annually?

Answer 292

$300million

Question 293

what was the 2012-2020 WHO roadmap for NTDs?

Answer 293

series of goals and strategies vector controls established in 10 endemic countries (dengue) more than 1 million surgical treatments were provided (trachoma)

Question 294

What is the definition of eradication?

Answer 294

permanent reduction to 0 of the worldwide incidence of infection caused by a specific pathogen no risk of reintroduction

Question 295

What is the definition of elimination?

Answer 295

reduction to 0 of the incidence of infection caused by a specific pathogen in a defined geographical area with minimal risk of reintroduction continued action to prevent re-establishment of transmission may be required

Question 296

What is the definition of 'elimination as a public health problem'?

Answer 296

reduction of infection and disease to measurable targets set by the WHO continued action is required to maintain the targets and/or to advance interruption of transmission

Question 297

What is the definition of control?

Answer 297

reduction of disease incidence, prevalence, morbidity, and or mortality to a locally acceptable level continued interventions are required to maintain the reduction

Question 298

what disease is on the verge of eradication with only 54 human cases reported in 2016?

Answer 298

dracunculiasis

Question 299

what are the WHO 2021-2030 targets for NTDs?

Answer 299

aim to free more than 1 billion people who currently require interventions against NTDs and reduce out of pocket expenditure 90% reduction in people requiring NTD interventions 100 countries having eliminated at least one NTD 2 NTDs eradicated

Question 300

what are core strategic interventions for NTDs?

Answer 300

preventative chemotherapy WASH - water sanitation, hygiene veterinary public health case management

Question 301

how many people don't have access to basic drinking water services?

Answer 301

785 million

Question 302

how many people practise open defication?

Answer 302

946 million

Question 303

types of diagnostics for NTDs

Answer 303

need them to be cheap and easy to run - require little training need molecular tests that rely on a biomarker antigen - LFTS antibody - ELISA, rapid lateral flow test (IgM, IgG) Nucleic acid - PCR, LAMP

Question 304

how does a lateral flow test work?

Answer 304

1. Identify a biomarker 2. add biological sample to sample pad 3. the sample flowing through conjugate pad that contains labelled antibodies specific to the antigen 3. antibodies specific to antigen are also adhered to test line 4. if antigen is present is present it is captured by the test line along with the labelled antibodies, visible as a line

Question 305

what is sensitivity in terms of a diagnostic tool?

Answer 305

true positive rate | the proportion of people who ARE positive that TEST positive

Question 306

what is specificity in terms of a diagnostic tool?

Answer 306

true negative rate | the proportion of people who ARE negative that TEST negative

Question 307

what are the features of a good diagnostic tool in terms of specificity?

Answer 307

it depends on the incidence/burden of the disease: | must have higher specificity when the disease incidence is low

Question 308

what are common challenges when it comes to NTDs?

Answer 308

political instability - funding, disruption, migration, refugees climate change - alters vector-borne disease epidemiology and spread antimicrobial and insecticide resistance - expansion of preventative chemotherapy, widespread use of insecticides for vector control zoonosis - animal reserviour

Question 309

What is schistosomiasis?

Answer 309

caused by 6 different species of parasitic worms humans are infected through contaminated water most species live in the mesenteric vein system of humans

Question 310

how is schistosomiasis transmitted and spread?

Answer 310

transmitted through contact with infected water (human = definitive host) the worm lives in the mesenteric vein system female worms lay 200-3000 eggs each day in the blood humans excrete eggs in faeces or urine when contaminated faeces or urine reaches freshwater, the eggs hatch they swim to the snail (intermediate host) of the right species and the parasite migrates through the snail and ultimately sheds larvae they swim to find a new host and reinfect by penetrating the skin

Question 311

how many people are affected by schistosomiasis worldwide?

Answer 311

240 million people | in 2016 there were 24000 deaths and 2.5 million DALYs

Question 312

what is the pathology of schistosomiasis?

Answer 312

initial rash at the site of inoculation Katayama syndrome - acute phase - nocturnal fever, cough, headache, abdominal tenderness, lasts 14-84 days chronic phase - weakness, fatigue, abdominal pain - fibrosis and lesions of organs containing trapped eggs - kidney disfunction - fertility issues associated with - undernutrition - lost years of schooling - growth stunting - exercise intolerance

Question 313

what strategies have the WHO introduced to eliminate schistosomiasis?

Answer 313

``` preventative chemotherapy to break the chain of transmission praziquantel - recommended drug improved sanitation access to potable water access to toilets - stop open defecation sewage treatment snail control - molluscicides vaccines - no current vaccines ```

Question 314

what is the life cycle of dracunculiasis/ guinea worm disease

Answer 314

people become infected when they drink water containing copepods (water fleas containing infective larvae) the copepods are killed by digestive juices of the stomach released larvae move to the small intestine where they penetrate the intestinal wall and migrate to connective tissues of the thorax and abdominal wall blister forms on the skin where the worm will eventually emerge (legs and feet) blister bursts within 24-72 hours when blisters are submerged in water, the worm releases larvae which are ingested by copepods and the lifecycle begins again.

Question 315

what is the epidemiology of dracunculiasis/guinea worm disease

Answer 315

affects poor communities in remote parts of Africa with no safe drinking water transmission has a seasonal pattern -in dry regions, people get infected in rainy season - stagnant surface water -in wet regions peole get infected in dry season - surface water is stagnant most common in 15-45 yr olds - farmers, herders, fetching water greatest risk is if you were infected the year before

Question 316

what is the pathology of dracunculiasis/guinea worm disease?

Answer 316

``` the worm is 2mm wide and 60-100cm long no symptoms first year and then people become ill - fever - rash - nausea - vomiting - diarrhoea ``` wounds often become infected - sepsis - tetanus - abscess rarely lethal disability that occurs during worm removal and recovery prevents people from working, going to school, caring for family for around 8.5 weeks but it can be permanent disability

Question 317

how is dracunculiasis/guinea worm disease managed?

Answer 317

no vaccines or drugs once part of the worm emerges, it;'s pulled a few cm each day by being wound around a stick or gauze process takes weeks

Question 318

what is the dracunculiasis/guinea worm disease eradication programme?

Answer 318

drink only from protected water sources cook fish and aquatic animals well before consuming prevent people with blisters/visible worms etc emerging skin in water distribute basic water filters chemically treat unsafe water only 28 cases reorted in 2018

Question 319

what causes African sleeping sickness?

Answer 319

the Trypanosoma brucei parasite - unicellular and extracellular 2 different sub-species of African trypanosome

Question 320

how is African sleeping disease transmitted?

Answer 320

Tsetse flies

Question 321

what is African sleeping disease?

Answer 321

humans - fatal disease - 1000 cases per year - no vaccine and treatments can be highly toxic animals - called Nagana - major cause of poverty - have to kill livestock

Question 322

what defines the distribution of African sleeping disease?

Answer 322

the vectors - tsetse fly only occurs in 36 sub-Saharan countries these people are most exposed to the fly the disease is in rural populations that are dependent on agriculture, fishing, hunting major disease loci in the DRC

Question 323

how is African sleeping disease controlled?

Answer 323

``` target parasite reservoir in host screening and treatment programmes in humans treatment of domestic cattle eliminating wild animal reservoir better health of population ``` target vector spraying insecticides insecticide-treated fly traps and bed nets blue fly traps

Question 324

what are the symptoms and pathology of African sleeping disease?

Answer 324

1. inflammation at bite site 2. early-stage - heamolymphatic stage - enter bloodstream 3. late-stage - encephalitic stage - trypanosomes cross the blood-brain barrier - fatal

Question 325

what is the life cycle of the trypanosome?

Answer 325

vector: tsetse fly host: mammls skin is a major reservoir adipose tissue is also.a major parasite reservoir - upregulating fat metabolic enzymes

Question 326

what are the 2 distinct lifestyle stages of trypanosomes in the host?

Answer 326

1. slender - long, proliferate, glucose metabolism via glycolysis, non-tranmissable. differentiate into stumpy form 2. stumpy - short, cell cycle arrested, active mitochondria, preadapated to survival in midgut

Question 327

describe the stumpy form of the trypanosome

Answer 327

this form proliferates at high parasitaemia, they differentiate into stumpy forms this is quorum sensing and is due to secreted parasite factors this limits parasitaemia and preserves the life of the host, enhancing parasite transmission stumpy forms are then transmitted via the tsetse bite

Question 328

summarise the trypanosome lifecycle

Answer 328

infect mammals transmitted by tsetse flies differentiate through multiple cell types to complete the lifecycle 1. slender - proliferative form in host 2. stumpy - non proliferative - transmissible form preadapted for tsetse 3. procyclic - establishes tsetse midgut infection 4. metacyclic - non-proliferative form that develops in insect salivary glands that innoculate new host

Question 329

how do trypanosomes evade the immune system?

Answer 329

extracellular parasites SO ARE EXPOSED TO HOST IMMUNE FACTORS VSG - varient surface glycoproteins hydrodynamic flow - endocytosis

Question 330

what is antigenic variation?

Answer 330

its the switching of expression sites to evade the immune system trypanosomes have ~20 different VSG loci/expression sites at chromosome telomeres only the expression site is expressed - monoallelic switch to one that hasn't been seen yet

Question 331

what is symbiosis?

Answer 331

close biological interaction between 2 different species

Question 332

what is mutualism?

Answer 332

symbiotic relationship in which both species benefit

Question 333

what is commensalism ?

Answer 333

symbiotic relationship in which one species benefits and the other is not affected

Question 334

what is parasitism

Answer 334

a symbiotic relationship in which one species benefits while the other species (host) is harmed.

Question 335

what is the causative agent of Leishmaniasis?

Answer 335

Leishmania. spp

Question 336

how is Leishmania. spp transmitted?

Answer 336

sandflies

Question 337

what is the disease burden of Leishmaniasis?

Answer 337

350 million people live in endemic areas | 12 million infected

Question 338

what is visceral leishmaniasis?

Answer 338

viscera = organs fatal if left untreated in over 95% of cases caused by L. infanum and L. donovani

Question 339

what are the symptoms of visceral leishmaniasis?

Answer 339

irregular bouts of fever weight loss enlargement of spleen and liver and anameia

Question 340

what is cutaneous leishmanisasis?

Answer 340

cutaneous = skin caused by > 20 different species of leishmania most common form not usually fatal causes skin lesions, mainly ulcers usually heals within a few months leaves life long scares and serious disability or stigma

Question 341

what is mucocutaneous leishmaniasis?

Answer 341

mucocutaneous = skin and mucous membrane caused by Leishmania braziliensis leads to partial or total destruction of mucous membranes of the nose, mouth or throat

Question 342

why is the burden of leishmaniasis likely to increase?

Answer 342

population mobility - migration, movement of non-immune people to areas of high prevalence environmental changes - changes in urbanisation, human incursion into forested areas climate change - changes in temp, rainfall and humidity can have strong effects on vectors - alter distribution and transmission

Question 343

describe the cell biology of leishmania

Answer 343

there are 2 leishmania forms that invade vertebrate immune cells 1. promastigote - inoculated by the sandfly - elongated, flagellated form - powerful swimmer - invades phagocytic immune cells 2. amastigote - formed by promastigote after its first invasion - small, round - immotile flagellum - invades phagocytic immune cells - infects sandfly - found in mamallian bloodstream

Question 344

what is a digenetic parasite?

Answer 344

colonises two different species 1. vector: sandflies - phlebotomine 2. host - mammals

Question 345

how is leishmaniasis transmitted?

Answer 345

bite of female sandfly regurgitate leishmania parasites into the wound upon biting parasites in promastigote form infect mammalian host 1. promastigote uptake into parasitophorous vacuole 2. differentiation and diversion: differentiation to amastigote 3. amastigote escape and reinfect 4. amastigote replicate inside parasitophosphorous vacuole 5. escape and reinfection

Question 346

how do parasites get inside macrophages?

Answer 346

parasites are internalised via conventional phagocytosis parasites bind to phagocytic receptors stimulates phagocytosis pathway and parasite is internalised inside a parasitophorous vacuole parasites subvert the classic pathway nutrients destined for other parts of the cell are diverted to the PV to feed the parasites vesicles carrying parasite damaging factors are less able to fuse with the PV membrane the parasite prevents the macrophage from activating other immune cells that might inhibit the parasite infection

Question 347

life in the sandfly vector

Answer 347

sandfly insert mouthparts into skin and produce wound where blood flows into superficial capillaries amastigotes are taken into sandfly midgut leishmania development happens in digestive tract - extracellular

Question 348

what happens in the sandfly midgut?

Answer 348

parasites start in the midgut as amastigotes (shortened, immotile flagellum) transform into promastigotes in resposne to temp and pH drop promastigotes progress through 5 stages 1. colonize midgut 2. nectomad - attached to midgut microvilli 3. leptomonad 4. heptomonad 5. metacyclic

Question 349

how do parasites overcome insect defences?

Answer 349

chitinases to break free of matric that surround them resist proteases by secreting inhibitors downregulate protease genes in sandfly insert flagellum between insect gut epithelium microvillli and bind to receptors to prevent them from being expelled secrete peptides that inhibit insect gut peristalsis movements

Question 350

Of the 900 + sandfly species, how many can transmit leishmania?

Answer 350

98 - high specificity with ability of parasite to bind to the phosphglycans on the epithelial microvilli

Question 351

what is the blocked sandfly phenotype?

Answer 351

Promastigote secretory gel blocks the valve containing many infective parasites the plug forces the valve to remain open and causes a blockage that reduces the inflow of blood this promotes delivery of parasites to the host via regurgitation these flies also feed more often because of feeding being inefficient

Question 352

what pharmacologically active compounds are in sandfly saliva?

Answer 352

anticoagulants to prevent clotting vasodilator peptides to promote blood flow -attracts macrophages to bite site -activates macrophages for Leishmania infection

Question 353

what 4 different species cause human malaria?

Answer 353

plasmodium falciparum - causes most deaths p. vivax- uncomplicated malaria p. avale - uncomplicated p. malariae - uncomplicated

Question 354

what is the geographical distribution of malaria?

Answer 354

94% of cases and deaths were in Africa 41% of worlds population live in areas where malaria is transmitted

Question 355

what is the pathology of malaria?

Answer 355

characterised by bouts of fever occurring every other day - up to 40.5 degrees linked to synchronised release and invasion of parasites from RBCs

Question 356

what are the 2 types of malaria?

Answer 356

uncomplicated - fever (hot and cold cycles), parasitaemia, anaemia complicated - severe anameia, cerebral malaria (coma and death), caused by P. falciparum

Question 357

what causes complicated malaria?

Answer 357

infected cells undergo changes in their cell surface RBCs change shape and develop knobs these knobs contain the parasite protein pfEMP1

Question 358

what is the impact of pfEMP1 in malaria development?

Answer 358

pfEMP1 on the infected RBC knobs are sticky - can bind to at least 7 different receptors on the endothelium. also, stick to non-infected erythrocytes forming a rosette. infected RBCs are less flexible which makes it difficult to pass through microvasculature - sequestration and causes vascular occlusion which blocks blood flow - this enables the parasite to avoid spleen dependant killing mechanisms

Question 359

how does sequestration causes cerebral malaria?

Answer 359

sequestration of parasite in the brain | blocked capillaries in the brian become swollen and congested leading to haemorrhage, coma and then death

Question 360

why is plasmodium a digenic organism?

Answer 360

requires 2 hosts to complete lifecycle vector - anopheles spp - mosquito host - human

Question 361

what happens when mosquitoes feed from blood vessels?

Answer 361

during feeding they continuously release saliva the saliva contains anti-clotting chemicals and bioactive compounds infected mosquito saliva contains plasmodium parasites sporozoites (spores) pass through the mosquito proboscis into the dermis upon biting once inside the parasites move around until they reach a blood vessel - gliding motility

Question 362

describe the liver stage of invasion of malaria

Answer 362

sporozoites reach the liver within 1 hour post-infection they attach to Kupffer cells and then cross into the liver they then transmigrate through several hepatocytes and then switch to invasion mode and start to replicate inside parisotophophorus vesicles (PV) eventually develops into thousands of merozoites by membrane invagination these rupture PV membrane and enter host cytoplasm eventually merozoites reach the lungs to infect RBCs

Question 363

SPOROZOITES IN LIVER & MEROZOITES OUT OF LIVER

Question 364

What happens to merozoites in the RBCs?

Answer 364

they enter the RBCs inside a PV using invasion machinery merozoite undergoes multip,e nuclear divisions to produce a schizont this matures via division, releasing merozoites from the PV 16-32 merozoites egress from RBCs to infect new RBCs MEROZOITES IN RBCs & MERZOITES OUT OF RBCs

Question 365

merozoites are non-transmissible so how is malaria transmitted to mosquitos?

Answer 365

they have to differentiate into transmissible gametocytes inside the RBCs - microgametocytes - analogous to sperm - macrogametocytes - analogous to egg needs to be a balance between keeping the infection going and transmitting the infection MEROZOITES IN RBCs & GAMETOCYTES OUT

Question 366

summary of parasite lifecycle in the mammal (malaria)

Answer 366

1. sporozoites inoculated into the dermis by the bite of an infected mosquito 2. pass into blood vessels and taken into the liver by blood flow 3. at the liver, they pass through several liver cells before they colonise a hepatocyte PV 4. sporozoite then develop into thousands of merozoites 5. merozoites re-enter the blood system inside vesicles m(merosomes) and replicate inside erythrocytes 6. merozoites are not transmissible 7. they must differentiate to gametocytes to transmit to mosquitoes

Question 367

what happens in the mosquito midgut?

Answer 367

fertilisation male gametocytes undergo flagellation male gametes fertilise female gametes to form a DIPLOID zygote zygotes differentiate into male ookinetes these become oocysts and lodge in basal lamina of midgut epithelium

Question 368

how dooes the parasite move from midgut to the salivary glands?

Answer 368

oocysts grow in size and produce 1000s of sporozoites by meiosis> haploid upon maturation, sporozoites are released into open heamolymph circulation of mosquito moves to salivary glands and into salivary gland cavity enter secretory duct and are transmitted upon biting

Question 369

give a summary of the lifecycle of plasmodium

Answer 369

1. merozoite - human RBCs 2. gametocytes - micro = male, macro = female) - transit to mosquito 3. gametes - insect midgut 4. ookinete - moquito midgut 5. oocyst - midgut epithelium 6. sporozoite - mosquito salivary glands, then human skin, then liver via blood system \

Question 370

what is the relationship between haemoglobin and sickle cell anaemia?

Answer 370

geographical overlap between sickle cell anaemia and malaria suggests the selective advantage of sickle cell heterozygotes against p. falciparum infection parasites are less able to grow inside sickled erythrocytes growth arrest

Question 371

what drug is used to treat malaria?

Answer 371

chloroquine resistance has emerged so rarely used in complicated malaria used in uncomplicated P. vivax

Question 372

what is the mechanism of action for chloroquine drug?

Answer 372

parasites metabolise haemoglobin to hemozoin crystals inside their food vacuoles haemoglobin is metabolised to hemozoin via heme which is toxic to the parasite but doesn't normally accumulate chloroquine becomes pronated in the low pH of the food vacuole and accumulates it prevents the breakdown of hemozoin causing toxic heme accumulation which lyses and kills the parasite

Question 373

what are the features of a 21st-century containment lab?

Answer 373

control of aerosols - no work on an open bench waste inactivation - autoclave negative pressure - stops contaminated air from escaping when doors are opened ability to fumigate - deals with spillages - formaldehyde effluent disinfection - everything put down the drain goes through disinfectant system

Question 374

what are the classifications of biological agents based on?

Answer 374

severity of disease risk to workers likelihood of community transmission availability of vaccines or effective treatments

Question 375

what are features of a hazard level 1 agent?

Answer 375

unlikely to cause human disease e.g., E.coli lab strain

Question 376

what are features of a hazard level 2 agent?

Answer 376

can cause human disease maybe hazardous to employees unlikely to spread to the community usually effective prophylaxis is available e.g., influenza

Question 377

what are features of a hazard level 3 agent?

Answer 377

can cause severe human disease may be a serious hazard to employees can spread to community usually effective prophylaxis, treatment available e.g., SARS-CoV-2 TB P. falcuparum

Question 378

what are features of a hazard level 4 agent?

Answer 378

causes severe human disease a serious hazard to employees likely to spread to the community usually no effective prophylaxis/treatment is available e.g., Ebola,

Question 379

how are aerosols managed?

Answer 379

``` the following techniques generate aerosols: centrifugation sonication - break open cells flow cytometry and cell sorting vigorous pipetting action ``` control by use of MSCs (microbiological safety cabinets)

Question 380

what are class 2 MSCs?

Answer 380

sample protection operator protection used up to containment level 3 the most common mode of primary containment only effective if the airflow is undisturbed keep lab doors shut keep grilles clear

Question 381

what are class 1 MSCs?

Answer 381

high-level operator production not designed to provide sample protection can be used to containment level 3 less sensitive to disruption than class 2

Question 382

what are class 3 MSCs?

Answer 382

maximum operator protection sample protection environment protection can be used at containment level 4

Question 383

what is genetic modification?

Answer 383

introduction of foreign DNA into any organism by a method that doesn't occur naturally - the transformation of plasmids into bacteria - transfection/duction of tissue culture cells - mutagenesis - growth, storage, transport of any resulting organism GMO regulations require a risk assessment

Question 384

what are the general principles when it comes to controlling GI infections?

Answer 384

``` stool sample collection identify a source mode of transmission - helps define control measures diarrhoea - enteric precautions risk groups exclusion -48 hour microbiological clearance - negative stool samples ```

Question 385

what are the methods of GI infection transmission?

Answer 385

faeco-oral foodborne environmental airborne

Question 386

what are the 6 F's - vehicles of GI infection?

Answer 386

``` food flies fingers faeces fluid formites ```

Question 387

what are primary prevention methods of GI infections?

Answer 387

food-safety - farm to fork water quality - filter and disinfection public awareness - open farms, summer BBQs foreign travel - vaccines, drinking bottled water, not eating from street vendors

Question 388

what are the 4 high-risk groups for GI infections?

Answer 388

doubtful personal hygiene children aged 5 and under food handlers clinical, social care or nursery staff

Question 389

what are the rules surrounding GI infections and stool samples?

Answer 389

with suspected cases, a stool sample is required and is sent into the lab so pathogen can be identified negative samples required before returning to work

Question 390

what is the most common cause of Gi infection?

Answer 390

campylobacter - most common cause of gastroenteritis undercooked meats, contaminated water, animal contact generally mild illness low chance of person to person spread

Question 391

what is an antimicrobial agent?

Answer 391

antimicrobials are used to prevent and treat infections caused by microorganisms in humans, animals and plants includes antifungals, antiparasitic, antivirals, antibiotics

Question 392

how do antibiotics work?

Answer 392

the challenge is to avoid damage to human cells the target is the cell wall, cell membrane, folate/protein synthesis, DNA/RNA synthesis

Question 393

how to antivirals work?

Answer 393

challenge: viruses reproduce in human cells mechanisms of action: - inhibiting attachment/entry of virus to host cell - inhibiting reproduction e.g., acyclovir - inhibiting virus leaving cell

Question 394

how to antifungals work?

Answer 394

mechanisms of action - impact on cell membrane via ergosterol - act via cell wall

Question 395

how do microbes develop resistance?

Answer 395

natural process genetic diversity natural selection of resistance genes making them more abundant in the bacteria population 1. this spreads to other humans/animals 2. spreads to other bacteria - sharing resistance via horizontal gene transfer

Question 396

what role do antibiotics have in microbe resistance?

Answer 396

antibiotics kill off competing bacteria which aids the process as the strain of resistant bacteria is the one that's being transmitted to other people

Question 397

what are some examples of resistance mechanisms?

Answer 397

efflux- antibiotics are pumped out of the cell target modification immunity/bypass - stop antibiotic accessing target enzymes - stop antibiotics from functioning

Question 398

what is minimum inhibitory concentration?

Answer 398

the minimum concentration of antibiotics in which bacteria can grow e.g., culture with a strip that has gradated levels of antibacterial agent in

Question 399

what is the minimum bactericidal concentration (MBC)?

Answer 399

minimum conc of antibiotics that kills it add liquid cultures mixed with increasing concentration of antibiotics to a series of cultures

Question 400

what are the drivers of AMR?

Answer 400

misuse and overuse inappropriate prescribing inappropriately used - not finishing the course use for growth production/prophylaxis in animals low-quality drugs

Question 401

what are some issues with drug development?

Answer 401

lack of new drugs in pipeline market failure/wrong incentives more opportunity to recoup profit from drugs for chronic conditions, high cost cancer drugs from an AMR perspective - want drugs to be used as infrequently as possible infectious diseases are not seen as a priority as they are not very profitable

Question 402

what are some consequences of antimicrobial resistance?

Answer 402

harder to treat > higher fatality risk longer treatment> multi-drug resistant TB more expensive treatment length of stay increased use of drugs that were previously avoided due to side effects cost to individuals when unwell for longer

Question 403

how many deaths were associated with bacterial AMR?

Answer 403

4.95 million

Question 404

how many deaths were attributable to bacterial AMR?

Answer 404

1.7million

Question 405

what is the one health approach?

Answer 405

an approach that recognises the interconnections between humans, animals and environmental health cant just take the human perspective

Question 406

what is the most common STI in the UK?

Answer 406

chlamydia

Question 407

what are the symptoms of chlamydia?

Answer 407

``` pain when urinating discharge bleeding during/after sex, between periods or heavy periods lower abdominal pain testicular pain ```

Question 408

what are some complications of chlamydia?

Answer 408

Causes Pelvic inflammatory disease - can lead to infertility, miscarriage, ectopic pregnancy in males, it can lead to orchitis, prostates and rarely reactive arthritis, meningitis and infertility

Question 409

what is the second most common STI in the UK?

Answer 409

Genital warts

Question 410

What does the blood test offered to pregnant women looking for in terms of infectious diseases?

Answer 410

Hepatitis A HIV Syphilis needs to be done as early as possible to reduce vertical transmission

Question 411

what is the success of the HPV vaccine?

Answer 411

reduced HPV infection in 86% of young women | and pre-cancerous cervical disease by 71%

Question 412

when was relationship and sex education made statutory in all schools?

Answer 412

september 2020