Mod 7 Infectious Diseases Flashcards
(100 cards)
1
Q
What are the types of pathogens from relative smallest to largest?
A
- Prion
- Virus
- Bacteria
- Protozoa
- Fungi
- Endoparasite/Ectoparasite
2
Q
What is this?
A
Prion
3
Q
What is this?
A
Virus
4
Q
What is this?
A
Bacteria
5
Q
What is this?
A
Fungi
6
Q
What are these?
A
Protozoa
7
Q
What are endoparasites?
A
- Live inside host
- visible with naked eye
- tapeworm, roundworm, citrus leafminer
8
Q
What are ectoparasites?
A
- Live outside host
- Visible to naked eye
- Leech, tick, mosquito, lice
9
Q
What are some structural features and adaptations/virulence factors of prions?
A
- Non-cellular/non-living
- misfolded protein
- Cause disease by inducing misfolding in a normal protein
- Host B lymphocytes secrete factors that allow prions to invade lymphoid tissue, then infecting central nervous system & organs
- May ‘piggyback’ on other proteins to move through the gut
- cannot affect plants
- resistant to proteases (enzymes that break down proteins)
- can be passed between species
- misfolded proteins do not trigger immune response
- e.g. Mad Cow disease (human version CJD)
10
Q
What are some structural features and adaptations/virulence factors of viruses?
A
- Non-living/non-cellular
- can only reproduce/metabolise in host cell
- insert DNA/RNA into host cell to create viruses inside host cell - when cell is full it bursts and release viruses
- Protein coat (capsid) protects genetic material (DNA/RNA)
- Chemicals on surface allow virus to adhede to host cell as they are similar in structure to host cell surface receptors
- e.g. HIV
11
Q
What are some structural features and adaptations/virulence factors of bacteria?
A
- Prokaryote - no nucleus
- Flagella used for motility
- Pili/fimbriae allow adhesion to host cell surface and prevent bacteria being washed away by urine/mucus/cilia
- Capsules resist phagocytosis by host cells
- Secretes chemicals to damage host cells and destroy immune defences
- Bacterial biofilm binds to tissue & makes it harder to eliminate & detect
- e.g. E. coli
12
Q
What are some structural features and adaptations/virulence factors of fungi?
A
- Eukaryotic (nucleus)
- Can be single-celled or multicellular
- reproduce via spores/budding - can travel long distances
- can affect outer layer, sub-skin layer, or internal organs
- secrete hydrolotic enzymes that cause damage to host cells & provide nutrients for fungus
- cell wall made of chitin - structural strength and resistance to host immune attacks
- e.g. dermatophytes (Athlete’s foot, ringworm)
13
Q
What are some structural features and adaptations/virulence factors of protozoa?
A
- Paramecium (cillia), amoeba (pseudopodium), giardia (flagellum)
- Unicellular eukaryote (nucleus)
- don’t usually infect plants
- cillia, flagella, and pseudopodium can all be used for movement
- can “hide” inside host cells to evade immune system
- can reproduce asexually
- microtuble protrusion - thin, needle like extensions that can deliver proteins that cause host cell to create entry point
- e.g. Cryptosporidium (diarrhoea)
14
Q
What are some structural features and adaptations/virulence factors of endoparasites?
A
- some (e.g. roundworm) have a thick cuticle on surface that resists digestion by host enzymes
- Some change surface proteins to evade immune detection
- Some (e.g. Tapeworms) have a head with suckers and hooks to anchor themselves to organs
- many eggs have a thick wall resistant to environmental conditions
15
Q
What are some structural features and adaptations/virulence factors of ectoparasites?
A
- Many have claws or hooks to grip fur, hair, or feathers
- Many have suckers and barbs for firm attachment & anchor them in place
- Piercing/sucking/eating mouth parts
- some inject anticoagulants to prevent clotting & anaesthetics to make bite less noticeable
16
Q
What are the types of transmission?
A
- Direct
- Indirect (includes Vehicle and Vector)
17
Q
What is direct transmission?
A
- pathogens transferred via physical contact
- e.g. touch, transferring droplets
18
Q
What is indirect tranmission?
A
- pathogens transferred via a contaminated object
- includes vehicle and vector tranmission
- e.g. door knob
19
Q
What is vector transmission?
A
- type of indirect contact
- pathogens transferred either on or inside another living organism
- e.g. mosquito, fly
20
Q
What is vehicle transmission?
A
- type of indirect contact
- pathogens transferred between individuals and environment within a substance
- e.g. soil, air, water, food
21
Q
What is meant by Koch’s postulates?
A
conditions developed by Robert Koch that can be used to determine the specific pathogen that causes a disease
22
Q
What are Koch’s postulates?
A
- Identify - microorganism (MO) must be found in abundance in all diseased organisms and not in healthy organisms
- Isolate & Culture - MO is grown in pure culture, then accurately described & recorded
- Inoculate - cultured MO should cause the same disease to healthy organism
- Re-isolate & Identify - MO must be able to be isolated from experimental host & cultured, and identified as the same original MO species
23
Q
What were Pasteur’s experiments on microbial contamination?
A
- used swan-neck flasks with boiled broth inside
- tested 3 conditions: 1 was left to cool, forming condensation in the dip of the swan neck, 2 had the swan neck snapped off, and 3 was left to cool on its side
- microbial growth occured in conditions 2 and 3 but not in 1
24
Q
What did Pasteur’s microbial experiments prove?
A
- growth only occured in flasks where broth was exposed to external enviroment
- ∴ emergent bacterial growth came from external contaminants in the air and did not spontaneously occur
- disproved theory of spontaneous generation (microbes can arise from non-living matter)
- helped prove germ theory (diseases are caused by microbes)
25
What are some causes of diseases in plants in agricultural production?
* most plant diseases are caused by fungi, e.g. Panama disease in bananas
* overuse/misuse of pesticides lead to pesticide resistant parasites
* loss of genetic diversity (monoculture) decrease resistance to specific diseases
* increased temperatures lead to outbreak of plant diseases transmitted by insects (insect populations increase if conditions are optimal, desynchronisation of insects and natural enemies leave plants more susceptible)
26
What are some causes of diseases in animals in agricultural production?
* Cows are often fed prion-infected meat-and-bone meal, e.g. Mad Cow disease
* Overuse/misuse of antibiotics can lead to Abx resistant bacteria in farm animals
* Rise of intensive industrial agriculture - animals are closer together and viruses/bacteria can spread more easily, e.g Foot and Mouth Disease highly contagious virus, Mastitis bacterium
* loss of genetic diversity (inbreeding) decrease resistance to specific diseases
* Increase in 'hobby' farmers wihtout proper experience in animal husbandry (ability to perform health checks on animals)
27
What are some effects of diseases in animals in agricultural production?
* damages economy
* Red meat, wool, and dairy are important to Australian economy
* Beef is in top 10 Australian exports
* Wool is $2.6 billion industry
* Agricultural industry ensures food security
* Infectious disease can wipe out farmer's whole stock and damage their income
* FMD and Mastitis cause severe production & income losses
* Cows with Mad Cow disease must be killed and cannot be used for products, losing income and food
28
What are some effects of diseases in plants in agricultural production?
* damages economy
* grains and wines are both multi-billion dollar industries
* agriculture industry ensures food security
* many diseases reduce quality and quantity of crops - reducing farmer incomes
* many fungal diseases, e.g. Panama disease, mean farmers must cease use of contaminated fields & destroy all crops - they must start all over again - singificantly reduces income
29
What are some adaptations to facilitate transmission of airborne pathogens?
* able to remain suspended in air for long periods
* resist dessication
* cause sneezing and coughing in host which causes ejection and transmission
30
What are some adaptations to facilitate transmission of waterborne pathogens?
* able to colonise and multiply in water
* often have fimbriae/flagella for motility
* many are not destroyed by boiling water or water-treatment
31
What are some adaptations to facilitate transmission of vector-borne pathogens?
* vector is not affected by pathogen (able to carry pathogen without dying/getting sick)
* form in digestive tract/salivary glands of vector for easier transmission (biting/sucking/piercing)
* produce surface proteins that allow attachment to vector tissues
32
What are some adaptations to facilitate transmission of faeco-oral pathogens?
* stable in varied environments (stomach acid, low oxygen in large intestine)
* induce vomiting and diarrhoea to increase likelihood of transmission
33
What are some adaptations to facilitate transmission of soil-borne pathogens?
* form endospores to resist dessication
* stable in a range of environmental conditions
34
What are some adaptations to facilitate transmission of blood-borne pathogens?
take advantage of features of red blood cells to facilitate growth and development
35
What are some adaptations to facilitate transmission of sexual or vertical (mother-to-child) pathogens?
* capable of transmission across placenta where maternal and foetal cells interact
* capable of uterine invasion
* contaminates genital fluids - unprotected sexual activity facilitates transmission
36
What is the cause of Panama disease?
fungus enters through roots & starves plant of water and nutrients by destroying conducting tissues
37
How does Panama disease transmit?
* Direct - root-to-root
* Indirect - movement of infected plants/soil/vehicles/equipment/clothing, spores can remain dormant for years
38
What are the effects of Panama Disease on the plant?
* Yellowing & wilting of leaves
* Splitting of stems
* Conducting tissues are damaged so plant is starved of water & food
39
What are the effects of Panama disease on farmers?
* reduced yield = loss of profit, loss of trading opportunity
* economic loss = hardship & stress
* economic cost of vigilance & management of outbreak - loss of farming opportunity due to quarantined properties
40
What are the effects of Panama disease on Australia's economy?
* reduced yield = loss of international trade, reduced GDP (was $138m loss due to outbreak in QLD)
* lack of food security & increased cost of bananas in stores
* biosecurity issues - lack of trust in export
* economic cost of buying contaminated land for quarantine
41
What are adaptations of Panama disease to faciliate entry?
* Germination of spores is triggered by host root exudates (secretions) & sites of root injury
* hyphae develop & invade root tip
* Pathogen releases proteins into xylem that facilitate colonisation of the host tissues by disrupting the plants immune response
* capable of degrading saponins (chemical plant defense)
42
What are adaptations of Panama disease to faciliate transmission?
* thrives in warm climate & dry soil - spores live long & transport easily - one spore is enough to infect & kill host
* new spores develop in diseased/dead tissue & remain dormant in soil resevoirs for (up to 10) years
* can spread by root-root contact in high density
43
What are the passive defences of plants?
physical barriers and chemical barriers
44
What are some physical barriers of plants?
* thick cuticle - withstand enzyme attack
* small stomata
* bark around trees
* leaves hanging vertically - water drains away
* lignin in cell walls - reduces nutritional content, increases toughness of leaf
45
What are some chemical barriers of plants?
* Glucosides & saponins (soap-like) interfere with fungal & bacterial growth by disrupting cell membrane
* enzymes break down toxins (e.g. chinases break chitin)
* secrete chemicals toxic to insects/fungi or bacteria, e.g. eucalyptus
* chemical receptors detect pathogen (PAMPs) & activate next stage of defence - links passive & active defence
46
What forms the plant immune response?
* present in every cell of plant
* every cell has ability to respond & recognise a pathogenic attack
* they do NOT have an adaptive immune system, only innate
47
What is the plant's active defence?
Pathogen recognition:
* plants wait until pathogen is recognised before producing toxic chemicals/defence proteins
* due to high energy costs & nutrient requirements with production and maintenance
Rapid Active response: (minutes to hours)
* guard cells close when PAMPs recognised
* reinforcement of cell wall & apposition (cell wall growth)
* apoptosis
* release H₂O₂ (hydrogen peroxide)
* release non-specific antimicrobial compounds
Delayed Active reponse: (hours to days)
* repair wounds - cork & gum secretions
* lysozyme-like chemicals have antimicrobial action
48
How does Phytophthora cinnamommi transmit?
* Direct - root-to-root
* indirect - soil, water run-off
49
What are phytophthora cinnamommi adaptations for infection?
* spores survive in environment for year (thick wall)
* spores resiliant to extreme environment
* motile spores in water
* appressoria help penetrate plant roots
* effector proteins suppress immune system
50
What are phytophthora cinnamommi adaptations for transmission?
* can infect plants across a range of environments
* rapid reproduction in wet seasons
51
What plant does phytophthora cinnamommi primarily effect?
eucalyptus
52
What are some passive eucalyptus defenses to P.cinnamommi?
* stored oils act as antifungal agents
* vertically hanging leaves prevent formation of moisture and mould
53
What are some active eucalyptus defenses to P.cinnamommi?
Rapid:
* stomata close to prevent entry
* cells produce H₂O₂-like moleccule
* express genes encoding proteins that degrade fungi chitin
* damaged tissues exude resin to seal/trap fungi to prevent spread
Delayed:
* release toxic compounds, e.g. tannins
* energy is rallocated from growth to defence
* signals for enhanced defence are sent to uninfected parts of plant
54
What is the hypersensitive response?
* cells detect pathogen + PAMPs
* cells send a message to reinforce cell wall
* increases cellulose & lignin
* signals to other cells to also do apposition
* cell contains pathogen
55
What are associated molecular patterns?
* signals sent to other cells & plants after cell recognition
* PAMPs - pathogen
* DAMPs - damaged cells
* HAMPs - herbivore
56
What are some physical changes that occur in host animal cells after recognising a pathogen?
* Inflammation (vasodilation)
* Phagocytosis – engulfing action
* Increased vascular dilation
* Vomiting (pathogens in gut) and diarrhoea (expel micro-organisms)
* Increased urination (bladder infection)
* Cells die and form a physical capsule – pustule, abscess or granuloma
* Wound healing – platelet plug and fibrin forms a mesh
57
What are some chemical changes that occur in host animal cells after recognising a pathogen?
* Cytokines in inflammation
* Phagocytosis (enzymes used to digest)
* Antibodies produced
* Urine – urination assists in keeping pathogens out of our urinary tract.
* Sebum – oily material that lubricates the skin
* Sweat - contains lysozymes.
* Tears – contain Lysozymes which digest bacterial cell walls
* Saliva – contains IgA and lysozymes
* Gastric acid secretions
* Fever – chemically induced
58
What makes up the human immune system?
59
What is the difference between the innate and adaptive immune system?
Innate - non-specific
Adaptive - specific
60
How does the innate immune system respond to a pathogen?
1. Physical barrier (sking) is broken & pathogen enter
2. Mast cells detect damage & release histamines
3. Vasodilation occurs (increased permeability → swelling, increased blood flow → warm, red)
4. White blood cells are squeezed out of capillaries and perform phagocytosis
61
How does adaptive immunity happen?
Innate Immune System:
1. WBC (macrophage) kills the pathogen and presents its antigen on its surface
2. Become an antigen presenting cell
3. macrophage presents antigen to a specific T helper cell inside lymph node
Adaptive Immune System:
1. T helper cell releases chemical signal cytokines to B cells and cytotoxic T cells specific to pathogen antigen
2. B cells undergo rapid mitosis & differentiation
3. half of B cells become plasma cells - produce antibodies to neutralize pathogens
4. half of B cells become Memory B cells - long lived (~10 years), allow for faster & amplified secondary immune response
5. cytotoxic T cells undergo rapid mitosis & proliferation
6. Half become Memory Tc cells
7. Half release perforins on infected body cells which display the antigen, killing the cell
8. Macrophages phagocytise and digest dead body cells and neutralised pathogens
62
What are the types of adaptive immunity?
Active:
* long lived
* slow
* immune system makes its own antibodies
Passive:
* immediate
* short-lived
* given antibodies made by a different organism - not produced by your own body
63
What are the types of active adaptive immunity?
Natural:
* become immune after catching a disease (memory B and T cells)
Artificial:
* vaccination
64
What are the types of passive adaptive immunity?
Natural:
* mother-to-baby via placenta & milk
Artificial:
* injections containing antibodies from someone else (e.g. blood/plasma donation)
65
What are the differences between primary and secondary exposure to a pathogen?
Primary:
* starts with little/no antibodies and memory cells
* takes 7 days to reach peak antibody production
Secondary:
* starts with some memory B and T cells (starting amount increases with every exposure)
* takes 3 days to reach peak antibody production
* plasma cell cloning stops & antibody production slows around 10 days
66
What are some methods of preventing the spread of diseases?
Behaviour changes:
* wearing condoms
* washing hands
* insect repellent
Vaccines:
* if many are vaccinated, this can create herd immunity
Medication:
* antibiotics
Surveilance:
* monitor diseases
* characterise disease patterns
* detect outbreaks
* notifiable diseases - health department
* local and state government
Environment:
* vector control
* safe water
* improving sanitation & hygiene
* housing & working conditions
* safe & clean food
67
What is incidence?
a measure of how many people are infected by a disease for the first time over a period of time (i.e. rate at which disease develops)
68
What is prevalence?
a measurement of the number or proportion of cases of the disease in a population at a given time
69
What is an example of using vector control to prevent the spread of diseases?
Mosquitos:
* NON-GMO sterilising males with x-rays so they can't breed
* NON-GMO wolbachia-infected mosquitos are resistant to dengue fever, zika, and chikungunya
* GMO mosquitos where all offspring die in larval or pupal stage
* GMO mosquitos that die when infected by a virus (e.g. malaria)
* Inescticides/pesticides
* Using insect repellent
70
Why is quarantining agriculture important?
* Agriculture industry makes $30billion/year
* demand for Australian produce to be pest/disease-free
* Australia is an island nation - advantage
* Quarantine minimises risk of exotic pests & disease entry
* protects native flora & fauna, agriculture industry, environment, and human health
* Animal quarantine - pets
* Plant quarantine - timber, fruits, cuttings
* Human quarantine - rabies, malaria, yellow fever
71
How can pesticides prevent the spread of disease?
* insecticides kill insects
* fungicides kill fungi
* herbicides kill weeds
* insecticide treated nets prevent malaria
* however, some insecticides like DDT (now banned) are very harmful for the environment and humans
72
How does COVID transmit?
Direct - droplets, saliva
Indirect - contaminated food or water, fomite, airborne droplets
73
What were some local strategies of managing COVID?
* Immunisation to create herd immunity
* personal hygiene practices - washing hands, hand sanitiser, masks, cleaning surfaces, isolation when sick
* improving public knowledge of disease & prevention
* contact-tracing
* COVID testing stations
74
What were some regional strategies of managing COVID?
* continued surveillance of health data, rapid recognition of disease presence (public health programs), diagnosis of microbial cause
* quarantine - travel ban between domestic areas and within region
* environmental - increased sanitation facilities
* lockdowns & work from home strategies
* encouraging social distancing
* Asia was founf to be more prepared and resilient, allocating emergency funds and tracking disease & quarantining
* Europe struggled to coordinate efforts
* North America lacked public health funding and seriousness to adress pandemic
75
What were some global strategies of managing COVID?
* communication between countries and world health organisations
* quarantine - implenting international travel bans
* vaccine development & free rollout
* public awareness campaigns
76
How effective was quarantine & lockdown in managing the spread of COVID?
* effective - prevented & slowed pandemic spread
* helped reduce to an endemic
* however, had negative effects on economies (especially tourism) and mental health
77
How effective were vaccinations in managing the spread of COVID?
highly effective in preventing death and severe reactions, as well as preventing hospital overflow
78
How effective was tracking disease & mobility of infected individuals in managing the spread of COVID?
* effective in catching disease early before further transmission
* less effective in actually preventing infection
79
How effective was personal hygiene in managing the spread of COVID?
* proven to be effective in slowing & preventing transmission
* masks have a risk reduction of 70%
* however, they must be done simultaneously, not just one method
80
How effective was public education in managing the spread of COVID?
* personal hygiene was widely used & normalised
* significantly encouraged people to get vaccinated
* helped reduce spread of misinformation
* however, some misinformation confused public
* often didn't reach rural or marginalised groups
* became less effective over time
81
What is the difference between a pandemic, endemic, and epidemic?
* Pandemic - global exponential disease growth
* Endemic - consistently present but limited to a particular region
* Epidemic - unexpected increase in the number of disease cases in a specific area
82
What are the symptoms of equine flu?
* fever
* watery nasal discharge
* cough
* lost appetite
* muscle pain
* laboured breathing
* horse looks depressed
83
How is equine flu transmitted?
Direct - nasal secretions & other bodily fluids
Indirect - humans' contaminated shoes, clothing, and grooming equipment, and food and water buckets
84
Describe the equine flu outbreak in Australia
* Epidemic in August 2007
* Centennial Park Sydney & breeding stallions from Japan at Eastern Creek Quarantine Stations (after import)
* At peak - 47,000 horses on 5,943 properties in NSW infected
85
What was done to manage the equine flu outbreak?
* lab tests confirm outbreak → emergency protocols
* statewide lockdown of all horse movements → eventually nationwide
* management centre set up to coordinate disease control
* horse properties quarantined throughout NSW
* disease was mapped - by end of August was in Central Coast and Hunter regions
86
What was done to prevent future equine flu outbreaks?
* restrict imports of live horses to approved countries
* biosecurity measures - quarantine for 14 days prior to export and upon arrival
* public education for horse industry workers - early detection
* biosecurity training for horse import staff, e.g. grooms, truck divers, cleaners, and airline staff
* vaccination is NOT feasible - virus mutates in same way as human influenza, so vaccination would not protect against new strains
87
How effective was the management of equine flu?
* outbreak was controlled by December 2007 - effective quarantining
* Australia was free of virus in early 2008
* EARLY vaccinations could have reduced new infection by ~60%, reduced severity of outbreak, and size of infected area, however, virus still rapidly mutates
* mapping allowed gov to quarantine horses in area of infection & prevent spread
* national coordination of efforts implemented Incident Control System (risk management prevents future outbreaks)
* initial failures of biosecurity protocols and quarantine methods led to outbreak
* caused severe disruption to horse racing & equestrian industries, costing ~$1 billion AUD and financial stress to owners
88
What are some examples of bush medicine?
* Lemon-scented gum - natural insect repellent for mozzies
* Peach-leaf quinine - tea from leaves cures colds and possibly malaria
* Gumbi Gumbi - tea from leaves cures colds, paste cures rashes, washing hair gets rid of dandruff
* Soap tree - crushed leaves and water works as soap
* Moreton Bay Ash (Eucalyptus) - sticks burn like cigarettes & lasts two days, important for keeping fires lit
89
What are some contemporary applications of bush medicine?
Tea tree oil:
* antiseptic properties inhibit growth of many bacteria & fungi
* used as household cleaner, treat fungal infections of feet and nails, and relieve minor burns/stings/acne
Kakadu Plum:
* richest source of vitamin C in the world
* contains antibacterials, antivirals, antifungals, anti-inflammatories, and protects against carcinogens & mutagens
* used in global production of cosmetics, vitamins, pharmacological products, and food
Emu bush:
* antibacterial & antifungal agent
* traditionally used to sterilise tools
* currently trialling use as sterilisation medium for prosthetic implants
90
What are intellectual property rights?
rights of ownership to ideas, inventions, images, or other creations of the mind that can be used commercially
91
What is biopiracy?
Use of biological resources or traditional knowledge without consent
92
Why is recognition and protection of Indigenous cultural and intellectual property rights important?
* Currently, Aus laws do not protect Indigenous bush medicine intellectual property
* many feel there is not adequate recognition or protection of their culture
* many pharma companies have patented certain Australian plant properties → by law, Indigenous people cannot use the plant without permission from the company (biopiracy)
* they have a right to practice and pass down culture and traditions freely
* have a right to be financially compensated for their knowledge's contributions to science
93
What has been done to protect Indigenous property rights?
* Nagoya Protocol - agreement to protect Aus biological resources and those under custodianship of Indigenous people
* Macquarie Uni and NSW Yaegl Local Aboriginal Land Council record traditional knowledge & research medicinal properties of native plants while sharing ownership of any commerical outcome
94
What is an example of biopiracy?
Smoke bush:
* traditionally used for healing
* 1980s tests showed it could cure HIV in low concentrations
* 1990s Australia sold patents to US government, giving exclusive rights to develop compounds from smokebush and to licence them to other companies
* no acknowledgement of traditional Aboriginal knowledge
* traditional knowledge holders could be excluded from using the plant product without permission from US
95
How do you calculate the pevalence of disease?
96
How do you calculate the incidence of disease?
97
How do antibiotics prevent bacteria?
* Bactericidal - kills bacteria by destroying cell wall (petidoglycan)
* Bacteriostatic - slow bacterial reproduction (inhibits ribosomal production of proteins - can't reproduce)
98
Are antibiotics effective?
* Very effective since 1940s in reducing death due to infection
* however, abx resistance is becoming a big problem
99
What are antivirals?
Cannot kill viruses - can only slow production of new viruses
100
Are antivirals effective?
* not as effective as abx
* reduce severity & duration of viral infection
