Flashcards in The Role of Wildlife in Zoonotic Outbreaks Deck (19):
Which species did Ebola originate in?
Fruit bats carry virus asymptomatically
What was the link between animals and HIV outbreak?
Started in chimpanzees which were hunted by people for years without any outbreak, few isolate diseased individuals but no explosion
1920s = first time HIV spread through the population
1980s = first time AIDS was noticed
What HIV control programme might have spread the disease further?
Vaccination program that didn't use proper sterilisation methods
How many people have been infected with HIV? How many people have died of HIV?
75 million people infected with the virus
36 million people have died of HIV
What is a spillover event?
When disease jumps from wildlife to humans
Why should pathogens in wildlife concern you?
Transmission to humans has an impact on human health
Transmission to domestic animals
Cost of control
Unpredictability of emergence
Ability to move long distances
What are some examples of zoonoses that originated in wildlife?
Rabies (bats, terrestrial carnivores)
Ebola (bats, others)
West Nile Virus (birds)
Nipah virus (bats)
What is the most common tick-borne infectious disease in the UK, Europe and North America?
Lyme disease (Borrelia buurgdorferi)
What was identified as the cause for increase in the USA?
At first was attributed to increase in deer population.
On further investigation was actually found to be due to reduction in number of small mammal predators so more mice were around for the tick larvae to attach to resulting in more surviving and so more Lyme disease
Define spillover host
An animal in which infection is sporadic or can only persist if external sources of infection are present
Often domestic animals especially livestock/horses
Develop severe disease themselves and are capable of shedding virus in large quantities (amplifier hosts)
Pass infection to people
Define maintenance hosts
An animal in which infection can persist via horizontal transmission in the absence of any other source of infection
What are reservoir hosts?
Smallest number of animals needed to maintain infection and can be a mixture of species
What is the general process of a spillover event?
Infection in wild animal population -> spillover host (amplifier) -> human infection -> fizzle out/pandemic
What was the process of spillover for Hendra virus?
Hendra virus was first identified in fruit bats endemically and asymptomatically (took a long time to identify)
Horses were the spillover host
Horses infected people resulting in a pandemic
What was the spillover event for avian influenza?
Avian influenza virus present in wild birds endemically and asymptomatically
Poultry were the spillover host
Poultry infected people and it became a pandemic before fizzling out
What was the spillover event for Nipah virus?
Nipah virus found endemically and asymptomatically in fruit bats
Pigs were the spillover host
Humans were infected from the pigs resulting in a pandemic
How did fruit bats infect pigs with Nipah virus?
Deforestation for pig farms -> fruit bats on outskirts would fly over pig pens and drop fruit and faeces/urine which the pigs would eat and become infected
How was Nipah virus transmission to people more complicated than it first seemed?
Bats also found to urinate into cups collecting palm sap for local alcohol production which was also found to infect people