Emerging Infectious Diseases Flashcards
Define an emerging disease.
Previously UNKNOWN disease that suddenly appears or a KNOWN disease that suddenly appears.
Define a re-emerging disease.
A KNOWN disease that was previously declining.
How are diseases detected?
Public* Farmers* Health care worker Veterinarian Pathologist Epidemiologist Academic
*Do not overlook these, they are often the first to notice a change.
Who investigates (re-)emerging diseases?
State/Provincial and federal agencies.
Who responds to (re1)emerging diseases?
National, provincial, international, agencies and industries.
What are the 5 stages of cross-species disease emergence?
- Pathogen is exclusive.
- Reservoir transmits, but no transmission among new host species
- Reservoir transmits, with a few cycles of transmission among the new host species.
- Reservoir transmits, sustained transmission within the new host species.
- Pathogen exclusive to new host species/reservoir.
What are some examples of Stage 2 of cross-species disease emergence?
Rabies (reservoir = carnivore; dead end host = cattle and horses) WNV, EEEV, WEEV (reservoir = birds; dead-end hosts = humans, horses and dogs) Influenza H5N1 (reservoir = waterfowl and poultry; dead-end hosts = humans)
What are some examples of Stage 3 of cross-species disease emergence?
Mycobacterium bovis (reservoir = cattle, bison, elk; poor human-human transmission) Nipah Virus (reservoir = fruit bats; human-human and pig-pig transmission)
What are some examples of Stage 4 of cross-species disease emergence?
SARS (Reservoir = fruit bats; efficient transmission to humans) Schmallenberg Virus (resevoir species unknown, efficient transmission in sheep, goats and cattle) 2009 Influenza H1N1 "Swine Flu" (reservoir = swine; very efficient transmission in humans)
What are some examples of Stage 5 of cross-species disease emergence?
HIV/AIDs, Measles, Smallpox, Dengue fever, Yellow fever
What are the 4 drivers to pathogen emergence?
Land use changes
Food and ag systems
Environmental systems
Human behaviour
What are the 4 determinants of emergence?
Pathogen
Reservoir
Transmission
Host
What is the most important pathogen type?
Viruses
What percentage of known human pathogens are zoonotic?
61%
In what ways does a pathogen adapt?
Antibiotic resistance, increased virulence, mutations, evasion of host immunity.
How does phylogenetic distance affect the reservoir determinant?
Pathogens are more likely to cross between closely related species. If a pathogen crosses between distantly related species, it often causes very different and more sever disease.
What diseases does new host susceptibility apply to?
All diseases.
How does intensive agriculture affect new host susceptibility?
Genetically similar hosts managed under the same conditions will have the same susceptibility.
What factors increase transmission?
Increasing abundance of the reservoir, increasing pathogen prevalence, increasing contact between reservoir and new host.
What are the 4 portals of entry for trans boundary diseases?
Animals/animal products
Vectors
Fomites
People
What is a major culprit of increasing transmission?
Animal trade
What two ways have development and changing ecosystems increased transmission?
Urbanization increasing population density and changing land use changes the climate.
How has travel and tourism increase disease transmission?
More exposure to exotic diseases, animal-based tourism increases contact with both domestic and wildlife species.
What is transmission from intentional release?
Bioterrorism, bio-crimes and agroterrorism.
