INFECTIOUS DISEASES PT2 Flashcards
what is zoonosis
a infectious disease of animals that can be naturally transmitted to humans
describe the 3 disease phases
- infection
- incubation period- time from infection until symptoms appear
- disease- showing symptoms
- latent period- which is the time between infection and being infectius
- period of communnicability(infectious)- when infection can be passed to others, doesnt necessarily coincide with displaying symptoms
can some organisms go through a second latent period after infection when organism doesnt show any symptoms?
yes but can become active again such as herpes
list types of direct transmission - direct contact
- physical touch between infected host and susceptble host
-skin
sweat - tears
-vomit
-nasal secretions - blood
-saliva
-sexual fluids - urine
list some forms of direct transmission- close contact
- airborne droplets between an infected host and susceptible individuals due to close proximity < or = to 1.5m
- new host inhales the infected droplets
- coughing sneezing
list direct transmission- reservoir
- soil
- fomite- inanimate object that pathogen can survive on
list indirect transmission for a vector
- a living thing that transmitts
- mosquitos, fleas, ticks
as the insect becoes infected and hey feed on infected hosts the the disease is then transmitted when the insect bites a new host - malaria
list types of indirect transmission- airborne transmission
- spread when an infected person sneezes or coughs as droplets can handg in the air for a long time
- droplets can travel 1-2m and land on surfaces or objects including tables, telephones
such as covid
list indirect contact soilbourne/waterborne/vehicle transmission
- an inanimate object acts as an intermediary between the portal of exit form the reservoir and the portal of entry of the host
- pathogens can swim through water ( chytidomycosis)
- pathogen can be contaminated in the soil (crown gall)
- infectious soils can be carried on the soles of soles of tire treads
list the characteristics of bacteria
- unicellular
- prokaryotes - no membrane or membrane bound organelles
- plasmids(small loop of DNA)
- asexual reproduction(binary fission)
some have
- a flagelum fore movement (tail)
- slimy bacterial capsule to help stick to surfaces
how does bacteria cause disease?
- toxins which disrupt cell functioning or kills cells
- damage host tissue directly ( using it for nutrients or producing wastes)
- may produce an immune response so strong that it damages the hosts own cells
describe the invasion method for tuberculosis
enters through mucous membrane - mouth lungs nose
descrieb transmission of tuberculosis
direct from air (droplets) - cough, sneeze, talk from either humans or cows(zoonose)
descrieb the impact of tuberculosis on host (symptoms)
- coughing (chest pain)
- coughing up blood
- fever
- night sweats
- unintention weight loss
- headaches
- scarring of lung tissue
treat emant of tuberulosis
antibiotics- may take up to 6months
vaccination
invasion method for crown gall disease (agrobacterium)
- attracted to open wound by sugars/chemicals being released
- flagellated bacterium enters roots through open wound
- attaches to cells and plasmid DNA is inserted into plant DNA
transmission of crown gall disease
- indirect contact from soil reservoir
or from fomite(tools)
impact on host for crown gall disease
- galls (tumours) on roots and stems
- gall prevent the movement of water and nutrients
stunted growth
changes in gene expression
management strategies for crown gall disease
- disinfecting tools
- heat treat infected soil
- remove and burn infected plants
describe the 6 step life cycle of mycobacterium TB
- MTB enters the lungs
- MTB ingested by macrophage
- MTB multiply in white blood cells
- white blood cells burst releasing MTB to enter more WBC
- tubercle formes in lungs
- tubercle ruptures into lungs and MTB is coughed out
life cycle of crown gall disease
- bacteria enters roots from soil through wound
- bacteria transfer some DNA (plasmid)to plant cells
- bacteria reproduce in root forming gall
- gall detached and releases flaggelated bacteria in soil
process repeats going back to 1. as it swims to new host
what are the different types of antibiotics and how do they work
bactericidal - kills the bacterial cells
bacteriostatic- inhibits growth
works by
-1. repturing cell membrane
2. stop synthesis of new cell wall during cell division
3. inhibit enzymes essential for transcriptioin or translation
4. inhibit enzymes essential for metabolism
describe the characteristics of fungi
- Eukaryotic = has nucleus + membrane bound organelles
- cell wall of chitin
- reproduce by spores
- unicellular and multicellular
effects of fungi
mostly external causing inflamation and irritation of skin
invasion method of chytridiomycosis
- enters skin cells
transmission of chytridiomycosis
indirect- water bourne ( free swimming zoospores)
direct- contact between infected individuals
impact on host - chytridiomycosis
- thickening of skin affecting gas exchange and osmoregulation
- excessive shedding of skin
- lethargy
- legs spread outwards
- death
- sitting out in the open
- loss of rightening reflexes
describe the life cycle of chytridiomycosis
- single celled flagellated zoospore enters skin cell
- thallus forms
- new zoospore are produced in thalus as it matures (asexual)
4.zoospored released into water where they swim to find a new host
characteristics of viruses
- protein coat surrounding either DNA or RNA
- life cycle inside of cells making it hard for the immune systme to destroy and hard to treat with meds
- has a phospholipid envolope (derived from the hosts cells)
describe different invasion methods of viruses in general
- through a physical breach (cut in the skin)
- direct inoculation (mosquito)
- direct infection of the surface its self (mucus membrane)
describe the life cycle of a virus
- viral entry
- attaches to host cell membrane
- the hole forms in membrane
- the virus or its genetic contents are released into the host cell - viral replication
- viruses takes control of the host cells replicatino mechanism (DNA/RNA) - Viral shedding
- cell ruptures virus progeny are released to find new host cells
what is viral latency
- virus may remain dorment until conditions are favourable eg. cold sores
list the invasion method, transmission and impact on host for the virus influenza
invasion method- through mucus
transmission (indirect)- airborn (droplets)
impact on host
- fever/chills
- dry cough
-sore throat
- runny or stuffy nose
- headache
- tiredness/ extreme exhaustion
- muscle/joint pain
list the invasion method, transmission and impact on host for the ross river virus
invasion methos
- injected into blood by mosquito
transmission
(indirect) vector- mosquito bite
impact on host
- joint pain swelling/ stiffness
- skin rash
- fever/chills
- muscle aches
-headache
-fatigue
provide some info about the honey bee virus
- no known cure
- 24 known viruses
- no symptoms at a low level
sacbrood is a type of this virus
- it infects larvae which die and swell
- workers remove larvae which burts releasing viruses (direct) and infects more bees and larvae whoch can kill an entire colony
- death of bees can be detrimental as no pollination of crops can be done
what are the 2 different types of evolution of viruses
antigenic drift- sml changed that occur continually over time
antigenic shift- when two or more viral strain combine to form a new strain
describe the charcteristic of protista
- eukaryotes- meaning they have membrane bound nucleus and membrane organelles
– mostly unicellular but algae are multicellular - mostly microscopic
- asexual and sexual reproduction
decribe the invasion method of malaria
enters blood stream
describe the transmission (indirect) of malaria
injected intoblood with saliva from female anopheles sp mosquito (vector)
descrieb the impacts malaria has on host
- headache
- fever
- shaking
- chills
- fatigue
- destruction of blood cells
descrieb the life cycle of malria from humans to mosquitos
human
1. sporozoites injected into blood stream during mosquito bite
2. sporzoites asexually reproduce in the liver to form merozoites
3. merozoites enter red blood cells asexually reproducing to form gametocytes
mosquito
4. gametocytes transfetted to female mosquito during bite
5. gametocytes fuse to from zygote(sexual)
6. zygotes burrow through mosquito gut wall to form a cyst which produces sporozoites
7. sporozoites move to salivary gland
invasion method jarrah dieback
- indirect - zoo flaggelates (spores) enter roots
transmission of jarrah dieback
- indirect and direct
indirect pathogen is carried to new areas and host waterbourne
- movement of infected soil by animals = paws, gigging burrows
- movement of soils by humans = vehicles, tools
- between plants- root to root(direct)
list the impacts on the host that jarrah dieback has
- root rot
- hyphae grow though roots absorbing nutrients and destroying tissue preventing movement of water
- wilting, yellowing, drying of leaves
effects of jarrah dieback on ecosystem
- kills trees = lower biodiversity
- destroyes nesting sites for birds
- succession - to resistant grasses
- soil erosion
- changes to microclimate
describe the life cycle of jarrah dieback
- p cinnamomi penetrate root
- sporangia & chlamydospores form
3.sporangia releases zoospores into soil where they swim to new host
OR - if conditions are adverse chlamydospores lay dormant in soil until conditions are favourable (then release zoospores)
define endemic
disease is prevalent at constant rate within a population
define sporadic
disease that occur irregularly with a population
define epidemic
an increasse in cases of a disease over what is considered normal
define pandemic
epidemic that spreads across multiple continents
what are the 3 factors affecting the spread of disease
- growth of pathogen populaiton
- density of host population
- mode if transmission
describe how growth of a pathogen population effects spread of disease
- increased size of pathogen population
- increased risk of transmission
favourable environmental conditions can shorten reproductive cycle increase population size - infectivity- the ability of a pathogen to be transmitted between host and multiply
- the more easily the pathogen can be passed on the ore likely it is to survive
- virulence - the ability of the pathogen to cause severe disease in the host (may cause population decline)
- ability to live outside host - spores, fomite
- being asymptomatic while contageous (or displaying symptoms)
describe how the density of the host population
- the more densly populated a community is the more likely organisms are to come into contact with an infected organism
- solitary organisms vs grouping organisms
- zoonoses are more likely as reduced habitat leads to greater interactions between humans and wild animals
describe how the mode of transport effects spread of disease
- indirect( vector,airborne, soil/waterborne)
- direct (direct, contact, close contact, reservoir)
- multiple modes of transmission increases liklihood of transmission (covid-19)
describe some characteristics of the life cycle of the mosquito
- 50-200 laying eggs
- hatch 2-21 days depending on temp
- adults life 4 weeks
- feed on nectar but females need protein from blood to make eggs
- eggs laid in stagnent water
how is climate change effecting the spread of mosquito bourne disease
anopheles mosquitos live in tropical climate
- mean monehtly temp not below 18
- 60mm or + of rainfall each month
- little variaiton in day lenth
therefore climate change is expanding region with this type of climate further away from the tropics spreading thus creating largeer number of breeding grounds for mosquitoes to carry disease
management strategies of mosquito boune diseases
- anitmalrial drugs
- preventative drugs
- isolate individual
how to prevent mosquito bites
physical preventatives:
- cover windoes with mesh
mosquito nets over bed
- indoor residual pray with insectiside
- insect repellent on skin
- long sleeeves and trousers after sunset
list ways on how to disrupt mosquitos life cycle
- covering waterin tanks
- repairing leaks
- introduce secial fish that eat mosquitos
- put insectiside in water to kill larvae
- reclaim area by filling and draining
what is biosecurity
policy and regulatory framework thats designed to safeguard against biological threats to environments, organisms and humans
- aims in to restrict entry of disease causing agent, GMO or invasive alien species
list managemtn strategies for spread of diseases
quarentine)
immunisation (vaccination)
herd community
medication
describe quarentine in terms of limiting spread of disease
- isolattion of diease carried
- kept until disease free
- prevents contacted between infected and uninfected
- all food and animal products declared when travelling
- prevents introduction of exotic pests and disease to protect again agriculture
describe immunisation in term s of preventing the spread of disease
- a solution of weakened or inactive anitgens or pathogens that is introduced into the body to elicit an immune response
eg. flu, tetanus, whooping cough
what are herd communities
- large % of host population that become immune
- immunity from recovery of vaccination
- limits spread of disease due to few susceptible individuals to sustain spread
- infected hosts often come into contact with immune host
- protects vulnerable individuals such as young, old and immune system compromised
describe how we can cause disruption of pathogens lifecycle
- killing vector with insectiside at different stages
- phermone traps attract males
- removing habitat
-removing places for laying eggs - medications
what are antibiotics and how do they work in preventing spread of pathogens
- used to treat bacterial infections
- produced by fungi or bacterial cells
works by:
1. rupturing cell membrane
2. stopping synthesis of new call wall during cell division
3. inhibit enzymes essential for transcription/translation
4. inhibit enzymes essential for metabolism
what are antiviral
- most ly inhibits replication of virus by preventing
1. bindinf cell membrane
2. cell entry
3. uncoating of virus
4. nucleaic acid synthese (transcription/translation)
5. reassembling
6. exiting from cells
this sometimes kills the virus
what are physical prevention methods of preventing spread of disease
- handwashing
- long clothing
- air filtration systems
- face masks, glasses, overalls
- disinfect surfaces
- vaccinations
- spraying insectisides in aeroplanes
which pathogens can a resistance be built with and why
all pathogens, virus, protozoans, diseases, fungi as they contain nucleic acid therefore can be a subject to natural selection
describe the process of an antibiotic resistance
- affected people treated wth antibiotics
- kill off antibiotic sensitive strains of the bacterium
- some bacteria acquired resistance to the antibiotic by mutation
- resistant bacteria unaffected by the antibiotic
- next generation all resistant
difference between immunity and resistance
- antibiotic resistance is where an organisms DNA allows it ti tolerate a certain level of antibiotics
- immunity is when an organisms immune system is stimulated by the presence of a foreign pathogen
what is conjunction
this is the process the plasmid containing the trait is passed from one bacteria to another through a structure called pili
list some reasons for the widespread of antibiotics
- increase in availability of antibiotics
- uncontrolled sale in many countrues (without perscription)
- incorrect diagnosis/unessecary perscription
- improper use of antibiotics as livestock food additives for growth promotion.
susceptibility of urban areas due to epidemics and pandemics of infectious disease can be due to:
population density
- spread through close contact
- disease spread faster
variation in living conditions (sanitation, sewage, clean waer)
- if drinking water isnt cleaned properly it can contain pathogens
health care provisions (acess to vax, health care professionals meds)
- not enough doctors = incorrect treatment
- immunity= population will lack herd immunity
- infeccted individuals arent treated
- health education will raise awareness
computer models can project the spread of disease and simulate effects of vaccinations and super computing has enables models to predict the relationship of epidemics. what other factos do they contain
this info is collected to then manipulate variables to determine the most effective approach to tackle an outbreak
pathogen info
- infectivity = how easily it is spread between hosts
- virulence = degree of damage
- latent period = whenhost is asymptomatic
- infectious period
- antibiotic resistance
- treatment
host info
- size
- density
- immunity
- travel patterns
environmental info
- temp
- natural disaters
- sanitation and water
why are international co-operation and communication needed to evaluate the risk of the spread of disease, including the emergence of new viral disease.
- to help prevent major outbreaks
- develope vaccine
- share info with other governemnts
- serious diseases are required by law to be reported to health authorities liek malaria and TB
how and why do quarentine measures protect Aus agricultural industry and environment agains the influx of disease carrying materials and organisms in the face of increasing global trade and travel
due to globalisation travel has increased
in quarentine they must
- isolate disease carriers
- keep in quarentine till free
- all food,plant and animal products must be declared
- prevents introduction of exotic pests and disease
in order to prevent the spread of jarrah dieback, vehicles are banned from driving on some tracks when the soil is wet.
explain how this can prevent the spread of jarrah dieback.
- disease is spread (from plant to plant) by spores/zoospores
- zoospores are more active when it is wet
- vehicles pick up more (contaminated) soil when it is wet; (therefore) risk of transmission/spread is greater when the soil is wet
- vehicles can spread disease/spores over a large area.
list two structural features of protists that are no found in fungi
- protists are usually unicellular
- protists often have flagella.
- cell walls of protists are made of cellulose
list 2 examples of bacteria, fungi, protista, viruses infectious diseases
tuberculosis and crown gall of plants
chytridiomycosis,
malaria, jarrah die back
influenza, ross rover virus, honeybees.
name a human viral disease that is transmitted by an insect
ross river
name a disease that is caused by a protist and can be spread by water
jarrah dieback
what makes something an infectious
a disease caused by an invading pathogen and able to be transmitted from one organism to another
what is Anopheles in terms of mosquitoes
is the genus of a mosquito known for its predominant role in the transmission of malaria
describe the basic structure of a virus
a protein coat called a capsid surrounding the dna or rna in the virus.
what are endospores
Endospores enable bacteria to lie dormant for extended periods, and ensure the survival of a bacteria during harsh environmental conditions. These could be overpopulation, nutrient deficiency, or unfavorable climatic conditions
what is the function of a bacterial capsule
protecting bacteria from toxic compounds and desiccation and allowing them to adhere to surfaces and to escape the immune system of the host.
acts as a magic cloak
