Module 7 Infectious Diseases Flashcards
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 coughin 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
