2-Mosquitoes and Zoonoses Flashcards
The pathogen must develop in the mosquito to become what?
Infectious
How are most diseases acquired by mosquitoes?
Via blood meal.
The number of days it takes for the mosquito to become infectious depends on what 3 things?
This time period is known as what?
- Pathogen
- Mosquito
- Temperature
- Extrinsic incubation period
When is the disease transmitted by the mosquito?
During feeding.
What are the most important vectors of human disease worldwide?
Mosquitoes
What is an example of an anthroponotic disease?
Malaria
What are 2 examples of mostly anthroponotic diseases?
- Dengue
- Yellow Fever
What are 4 examples of true zoonoses transmitted by mosquitoes?
- Rift Valley Fever (FAD)
- Equine encephalitis viruses
- West Nile Virus
- Other flaviviruses
What does EEE stand for?
Eastern equine encephalitis
What does JE stand for?
Japanese encephalitis
What does LAC stand for?
LaCrosse encephalitis
What does MVE stand for?
Murray Valley encephalitis
What does POW stand for?
Powassan encephalitis
What does SLE stand for?
St. Louis encephalitis
What does TBE stand for?
Tick-borne encephalitis
What does WEE stand for?
Western equine encephalitis
What does WN stand for?
West Nile
What does VEE stand for?
Venezuelan equine encephalitis
What is the viral family of WEE, EEE and VEE?
Genus?
- Togaviridae
- Alphavirus
What do EEE, WEE and VEE cause?
In what 2 species?
- Encephalitis and/or febrile disease
- Horses and humans
What is the pathogenicity in equids for VEE?
EEE?
WEE?
- Up to 80% case fatality with some strains
- 90+% fatality
- About 20-40% case fatality rate
Are mosquitoes mechanical or biological vectors of EEE, WEE and VEE?
Biological vectors
With EEE, WEE and VEE, who become infected and develop high enough viral titers in blood to infect mosquitoes?
Reservoir hosts
What species is the natural reservoir for WEE and EEE?
Birds
What species is the enzootic reservoir for VEE?
The epizootic reservoir?
- Rodents
- Horses
How often do epizootics of EEE occur?
Periodically
Where do epizootics begin?
In nature.
Increased transmission of virus between mosquitoes and birds can lead to what?
Spill over to incidental hosts.
T/F: Many environmental factors contribute to spillover cycles.
True
What do you call hosts found outside the natural cycle?
Incidental hosts.
Incidental hosts are usually what?
What does this mean? What is an exception to this?
- Dead-end hosts
- Can’t infect mosquitoes, except both horses and humans with VEE
The enzootic reservoir cycle of EEE is between what 2 species?
- Wild birds
- Mosquitoes
What is the mosquito vector for EEE?
Culiseta spp.
The epizootic cycle of EEE is between birds what what hosts?
Incidental hosts
What are 4 examples of incidental hosts of EEE?
- Horses
- Humans
- Swine
- Ratites
What is an example of a “bridge” mosquito vector required with EEE?
Aedes spp.
Epizootics tend to be what and usually occur within how far of an enzootic swamp habitat?
- Self-limiting
- Within a few miles
T/F: Incidental hosts are dead-end.
True
Which is most virulent: EEE, WEE, VEE?
EEE
Equine cases of EEE often appear how long before human cases?
About 2 weeks
Early clinical signs of EEE include what 3 signs?
- Fever
- Lack of appetite
- Lethargy
What disease can progress to various degrees of excitability and then drowsiness, ultimately ending in paresis, seizures and coma in fatal cases?
EEE
Is there a vaccine for EEE in horses?
Yes
With swine and ratites, what are 2 clinical signs that can be seen with EEE?
- GI disease
- Hepatitis
What are 4 other species that can contract EEE?
- Sheep
- Cattle
- Deer
- Camelids
What is a risk factor for EEE?
Outdoor activities in an area with EEE-infected mosquitoes.
What is the incubation period of EEE?
3-10 days
What percentage of people will be asymptomatic with EEE?
90+%
What are 4 possible symptoms of EEE in humans?
- Mild flu-like illness
- Encephalitis
- Coma
- Death
What percentage of humans survivors of EEE will have mild to severe permanent neurological damage?
Approximately 50-90%
What is the estimated lifetime cost per patient for humans with EEE?
$3 billion
Is there any specific treatment for EEE?
No
What is the mosquito vector for WEE?
Culex tarsalis
