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MBB163 > Fenton - Pathology and Disease > Flashcards

Fenton - Pathology and Disease Flashcards

1
Q

what is a pathogen?

A

any agent that can cause disease (bacteria, fungi, viruses, protozoa (euks), prions - no archaeal pathogens described yet)

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2
Q

how is pathogenesis similar to parasitism?

A

One organism using resources of another in a way which is not beneficial to the host

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3
Q

name 5 things that make a pathogen successful

A

1) being able to access the host - oral/abrasion
2) locate nutritionally compatible niche - multiple infections for survival
3) avoid/subvert/circumvent the host’s innate and adaptive immune responses
4) access host resources and replicate (not necessarily causing disease)
5) exit and spread to a new host

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4
Q

name 3 ways in which you can measure how ‘successful’ a pathogen is

A

1) is the pathogen alive?
2) mortality: no of death from notifiable disease
3) morbidity: no of cases of a disease in the population

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5
Q

name 3 diseases with mortality rates approaching 100%

A

plague (pneumonic)
rabies (preventable)
vCJD (variant Creutzfeldt-Jakob Disease)

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6
Q

define infection dose

A

number of individual particles/cell required for infection

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7
Q

what is a virulence factor?

A

a particle that enables a pathogen to colonise a host - they’re NOT for causing disease

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8
Q

name the 4 methods of transmission of a pathogen

A

1) water
2) air/droplets
3) mechanical (eg mosquito carrying plasmodium falciparum biting you)
4) food

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9
Q

name 5 virulence factors and explain briefly how they work

A

1) adhesins - find a niche and colonise a host
2) capsules/S-layers - immune evasion/survival in a host
3) digestive enzymes - finding a niche, colonising and finding host resources
4) toxins - reprogram host biology that benefits the pathogen
5) ‘‘stealth mode’’ - lack of outer-surface factors - immune evasion

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10
Q

what is the difference in a pathogen and a parasite?

A

a parasite is something you can see with the ‘‘naked’’ eye - bit of a bad definition

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11
Q

what % of the world’s deaths are caused by infectious diseases?

A

~15%

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12
Q

name the 4 diseases with the highest morbidity caused by pathogens

A

1) lower respiratory infections (3.2 mil)
2) diarrhoeal diseases (1.4 mil)
3) TB (1.4 mil)
4) HIV/AIDS (1.1 mil)

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13
Q

what is ‘germ theory’ ?

A

the theory that many diseases are caused by microbes

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14
Q

name koch’s 4 postulates

A

1) microbe is found in all cases of disease but absent from healthy individuals
2) microbe isolated from diseased host and grown in pure culture
3) when the microbe is introduced into another host, the same disease occurs
4) when the microbe is isolated from the second experimental host and is cultured it is the same strain of microbe

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15
Q

name the main advance in combating disease over the last 200 years

A

better diet and clean drinking water (improved sanitation and less overcrowding in urban areas/better living conditions has also contributed)

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16
Q

name 3 methods of treating/preventing diseases

A

1) sanitation/antiseptics
2) vaccination
3) antimicrobials

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17
Q

what are vaccines?

A

chemical agents which prime the adaptive immune system to repel a pathogen

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18
Q

which disease did Robert Koch study? why was this?

A

anthrax (Bacillus anthracis).

this was becasue it frequently killed sheep and cattle

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19
Q

which 2 antibodies does vaccination stimulate? where are they found?

A

IgM - this one is made first and is found in the circulatory system or lymph nodes
IgG - made second and is found in the tissues (more variable)

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20
Q

describe the differences in antibody concentration in first and second exposure in vaccination

A 
first exposure (vaccination): IgM peaks first whilst IgG gradually increases
second exposure (when you're exposed to the disease): IgM peaks first but more slowly, IgG peaks massively and more quickly (than in 1st exposure)
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21
Q

after vaccination, if the subject can be exposed to the pathogen and does NOT develop the disease, they are said to be i_____

A

immune

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22
Q

how was smallpox originally treated? how did Edward Jenner develop this?

A 
Lady Montagu (1717) introduced an early form of vaccination by directly adding pus from Smallpox into the open vein of the patient (bit hit & miss)
Edward Jenner inoculated a patient with cowpox (a less virulent form of pox) creating a similar immune response = cross-protection
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23
Q

define the term ‘magic bullet’

A

a compound that can control pathogen infections without harming the patient

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24
Q

who discovered penicillin?

A

alexander flemming

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25
Q

what are antibiotics?

A

chemicals produced by bacteria and fungi that inhibit or kill other microbes

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26
Q

name 4 challenges of making penicillin

A

purification of the product
production (large scale)
proving penicillin was non-toxic
first human and animal tests

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27
Q

what process does penicillin inhibit?

A

cell wall synthesis

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28
Q

name 5 things that antibiotics can inhibit

A 
cell wall synthesis
protein synthesis
cell membrane integrity 
nucleic acid formation
intermediary metabolism
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29
Q

what 3 things make up disease?

A

symptoms - change in body function that is felt by a patient as a result of disease
signs - change in a body that can be measured or observed as a result of disease
syndrome - a specific group of signs and symptoms that accompany a disease

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30
Q

some pathogens can cause multiple diseases eg streptococcus pneumoniae. name 3 diseases caused by this pathogen

A

pneumonia
sepsis
meningitis

31
Q

some diseases can be caused by multiple pathogens eg pneumonia. name 3 possible causes of pneumonia

A

fungal
viral
bacterial

32
Q

what is pneumonia?

A

a reaction of the body to colonisation or damage to the airways

33
Q

name 4 ways in which microbiota benefit out health and well-being

A 
digestion
metabolism
immune function
mood and behaviour
(also may contribute to obesity, heart disease, diabetes)
34
Q

describe the 3 relationships between human and microbe and give an example of a microbe that fits each one

A

commensalism: one organism benefits and the other is unaffected (Staphylococcus)
mutualism: both organisms benefit (E. coli)
parasitism: one organism benefits at the expense of the other (any human virus eg flu)

35
Q

define disease

A

a disease state is the product of a relationship/conflict between host and pathogen

36
Q

what disease does C.difficile cause? what are the symptoms and the mortality rate?

A

Clostridium difficile causes Clostridium difficile infection (CDI). the symptoms are diarrhoea, and colonisation and inflammations of the colon
the mortality rate is ~9%

37
Q

describe the interactions between the microbiome, C. difficile and antibiotics.

A

The colon is packed full of MOs which are involved in the maintenance of our digestion (they are helpful MOs). After a treatment with antibiotics the microbes in the colon have been killed, the C. difficile then fills space causing an infection. This is described as an opportunistic infection

38
Q

define an opportunistic pathogen

A

microbes which are not normally pathogenic but can case infection or disease in a ‘compromised’ host.

39
Q

what are hospital acquired infections?

A

usually opportunistic infections that are a result of a hospital stay. a patient is often the source of their own infections eg C. difficile

40
Q

what is the effect of urbanisation on pathogenesis?

A

highly populated areas drive many potential routes of transmission

41
Q

which MO causes cholera? what are the symptoms of this disease? what is the mortality? what is the mode of transmission? what is the treatment? what is the major virulence factor?

A

Vibrio cholerae (bacteria)
symptoms: large amounts of water diarrhoea (rice water stool)
Virulence: death through severe dehydration, mortality low as 1% if its treated properly
transmission: faecal-ral route
treatment: oral rehydration/anitbiotics
major virulence factor: cholera toxin

42
Q

which disease did john snow investigate? what was the significance of this?

A

cholera - broad street water pump

led to the field of epidemiology - was the first disease to methodically investigated

43
Q

define epidemiology

A

study of where and when diseases occur to control spread of disease

44
Q

what are the 4 principles of epidemiology?

A

1) identify 1st person to have disease (patient zero)
2) identify anyone who had contact with that person
3) identify the reservoir for the pathogen
4) block/contain the reservoir

45
Q

what is the issue with blocking or containing a disease reservoir for a new pathogen?

A

disease must first be recognised (know what to look for)

problem with this is that many people may already be infected by this point

46
Q

describe the difference in epidemic diseases, endemic diseases and pandemic diseases

A 
epidemic: disease acquired by
many hosts in a given
area in a short time
Endemic: disease constantly present
in a population
Pandemic: worldwide epidemic disease
47
Q

which pathogen causes Typhoid fever? what are the symptoms? what is the reservoir/method of transmission? what is the virulence?

A

Pathogen: Salmonella enterica serovar Typhi (bacterium)
Symptoms: Rash (rose spots)
reservoir/transmission: human carrier (colonised gall bladder)
1-3% people exposed will permanently carry the disease
faecal-oral route
virulence: mortality is about 30% without treatment

48
Q

which pathogen causes Polio (poliomyelitis)? what are the symptoms? what is the reservoir/method of transmission? what is the prevention method?

A

pathogen: polio virus
Symptoms: irreversible paralysis (1/200), muscle weakness, atrophy, deformities, twisted feet/legs
reservoir/transmission: faecal-oral route usually via a contaminated water source
treatment: vaccine (attenuated virus)

49
Q

what are the problems associated with the polio virus?

A

in very rare cases the virus can revert into a form capable of causing disease and infection others.
in extremely rare cases some immunocompromised individuals appear to become healthy carriers - excreting large amounts of active polio virus for long periods of time

50
Q

describe the ‘‘Birmingham Man’’ case study and its effects on local (UK) and global populations

A

Birmingham Man is a healthy human carrier of the Polio virus - excreted virus for last 20-30 years.
If polio vaccination were to stop in the UK there would be a large risk of people contracting Polio.
If Birmingham Man goes on holiday to countries with no Polio vaccination program he is going to infect a large number of people with polio

51
Q

what is a healthy/asymptomatic carrier? name 2

A

healthy carriers are individuals that are capable of transmitting a disease to other but shown no signs of infection/display no symptoms eg Typhoid Mary and Birmingham Man

52
Q

which pathogen causes bubonic and pneumonic plague? what are the symptoms? what is the reservoir/transmission? what is the virulence?

A

Yersinia pestis bacterium
symptoms: buboes (swollen lymph glands)/pneumonia
reservoir/transmission: rodents/prairie dogs/rodent fleas & human respiratory aerosol (pneumonic - main drive of mortality)
virulence: extremely high mortality if untreated (bubonic: ~50%/pneumonic:~90-100%) treatable if <24hrs since 1st symptoms

53
Q

what is a zoonotic pathogen? what is an epizootic?

A

zoonotic pathogen: a pathogen that can be transmitted from animal to human
epizootic: animal equivalent of an epidemic

54
Q

what is the pathogen that causes potato/late blight? what is the virulence?

A

pathogen: phytophthora infestans (fungus)
virulence: ~100% crops

55
Q

where did blight come from? what was the impact of this?

A

Potatoes from S. America (Brazil/Peru/Bolivia)
Taken to Spain/Britain by sailors - only took a few species however
This introduced a tight population bottleneck and reduced genetic diversity
Pathogens share similar geographic distribution and usually co-evolve with their hosts

56
Q

which pathogen causes influenza? what is the virulence?

A

pathogen: influenza virus
virulence: v varied (0.01%-50%)/’newer’ strains have higher case fatality rates

57
Q

how are ‘new’ influenza virus particles made?

A

the re-assortment of genetic material in a host. eg pig being infected with bird and human flu virus can lead to the reassortment of the virus’, which can then infect humans

58
Q

which pathogen causes Zika? what is the virulence? what are the updated views on reservoir/transmission and virulence?

A

pathogen: zika virus
virulence: extremely low, most people won’t have symptoms at all
UPDATED
reservoir/transmission: sexually transmitted (semen): men = 6 months/women = 8 weeks
Virulence: associated with birth defects (microcephaly and Guillain-Barre syndrome)

59
Q

how are new diseases identified? use zika virus as an example

A

a disease is 1st identified as a geographically clustered pattern of symptoms and signs
Aug ‘15: newborns with microcephaly observed
Oct ‘15: state health secretary alerted about microcephaly - also an outbreak of mosquito-associated diseases at the same time
early ‘16: link between Zika and microcephaly established by ‘scientific consensus’

60
Q

which mosquito is the vector for Zika? which other pathogen can it carry?

A

Aedes mosquito

can also carry Dengue virus (higher virulence than Zika)

61
Q

what is epidemiological surveillance?

A

the collection, analysis and dissemination of public health data

62
Q

what are the 3 disadvantages of using epidemiological surveillance when identifying a new pathogen?

A

it takes time to do epidemiological surveillance
can be inaccurate
correlation based data falls very short of ‘cause and effect’

63
Q

what is the effect of Zika being sexually transmitted?

A

as of 2017 Zika is no longer found only where the Aedes mosquito is found - could possibly spread globally

64
Q

what has the CDC in the USA studied about Zika and transmission?

A

studied pregnancies where they know the mother has been exposed to the Zika virus (doesn’t take into account when she was infected)
the evidence shows Zika associated birth defect rate in the US =~5% BUT the chances of any pregnancy having a birth defect =~3% (is there a link between birth defects and Zika?)

65
Q

which diseases does the Ebola virus cause? what are the symptoms? how do the patients die? what is the virulence? what is the reservoir/mode of transmission?
what is the treatment?

A

diseases: Ebola virus disease and Ebola hemorrhagic fever
symptoms: bleeding
death: internal bleeding, die through shock, nerve damage and seizures
virulence: highly virulent, 70-90% mortality
treatment: untreatable

66
Q

when was ebola discovered? state the relative importance of the 2014-16 outbreak

A

discovered in 1976,
the outbreak in ‘14-‘16 was the largest and most complex since its discovery (28,616 cases (~40% people who caught it died)

67
Q

how was the ebola outbreak prevented from becoming a global pandemic?

A

in the early stages the outbreak was at exponential growth - strong international response (70-70-60 target)

68
Q

describe the 70-70-60 target in relation to the ebola outbreak

A

60 days: 70% of patients in isolation and ‘treatment’

70% ‘safe’ burials

69
Q

how were aid workers protected during the ebola outbreak?

A

use of protective equipment and isolation environments

70
Q

what are the long-term challenges with Ebola crisis?

A

ebola survivors have persistent carriage of the virus in semen and other fluids (dont really know how infectious the survivors are/how long it takes for the virus to clear)

71
Q

what is the single biggest challenge to global public health today? (according to WHO)

A

antimicrobial resistance (AMR)

72
Q

name 5 health challenges we would face without the use of antibiotics (only suggestions - there are way more than 5)

A

1) minor infections would become life threatening
2) surgery
3) child birth
4) chemotherapy (ie immunocompromised patients)
5) infectious diseases would claim many more lives (particularly the old and young)

73
Q

what is the significance in the relationship of drug discovery and antibiotic resistance?

A

drug discovery rapidly decreasing but AMR MOs are still present due to selection pressures being applied

74
Q

what makes antimicrobial resistance such a complex issue?

A

lots of different antibiotics to treat a wide range of bacterial pathogens, each with a different virulence and survival strategy. Each of these pathogens has a different resistance mechanism which are varied and poorly understood. This leaves a huge range of things we need to study, understand and synthesise.

MBB163 (12 decks)

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