Overview of infectious agents and principles of infectious disease transmission Flashcards
What is Virulence?
The degree of pathogenicity within a group / species of agent of infectious disease, as indicated by host fatality rates and/or the ability of the agent to invade the tissues of the host
What are the features of Foot and mouth?
- highly contagious, affecting upper alimentary tract and feet
- affects cloven hoofed species
- very resistant but severity depend on the subtype of virus and animal species
What are the features of Rabies?
- acute encephalitis in warm blooded animals
- transmits mostly through infected bites
- long incubation before clinical symptoms appear; 100% fatal within 6-14 days after onset
What are the features of Influenza?
- in nature, it is waterborne and enteric infections of water fowl
- adapts to domestic fowl, animals and humans readily
- varying pathogenicity for different species
- evolves constantly (mutation or recombination of genetic material
What are the features of Brucella?
- Intracellular, gram -ve rods
- leads to infertility, abortion and chronic arthritis in ruminant, swine and human
- transmits via birth material
What are the features of clostridium biotulinum?
- gram +ve rod, in anaerobic conditions
- pathogenic effect by toxin production
- can cause paralysis in extremely low quantities
- waterfowl in stagnant water (Summer)
What can Fungi lead to?
- dermal infections (ringworm)
- internal infections (coccidioidomycosis of lungs, Aspergillosis)
- mycotoxin production (alfatocicosis)
What does Trypanosoma cause?
- anemia, weight loss and death in animals and cerebral symptoms and death in humans
- extracelllualr blood parasites transmitted by tsetse fly
What are the different Macroparasites?
Helminths
- round worms (nematodes)
- flatworms (tematodes fluke)
- tapeworms (Cestodes)
Incects
- biting fly
- blow fly
- nuisance fly
Acari
- ticks and mites
What do nematodes affect?
- mostly in GI tract but also lungs, heart, blood, liver kidneys, skin, eye
- many are harmless
- major source of farm economic loss
What do Tematodes use as hosts?
- generally have snail intermediate hosts
What can Cestodes cause?
larval stage may cause pathogenic cysts
What are the features of Prions?
- misfolded proteins cause normal proteins to misfold
- causes brain cell death
- highly resistant to cleaning and disinfection
What is Canine transmissible venereal tumour?
- sexual contact
- all have same DNA as the Patti ent 0 from 11,000 years ago
- generally self limiting, regress after 3-6 months
What is Facial tumour disease in Tasmanian devils?
- transmit by fighting
- interferes with eating (death by starvation)
- serious concern for species conservation
