EEE surfaces nearly every year in the U.S., but with another outbreak of West Nile virus also spreading across the country, health officials are working hard to alert people about the serious risks that come with getting a mosquito bite.
The Conversation asked Daniel Pastula, a neurologist and medical epidemiologist from the University of Colorado Anschutz Medical Campus, to explain how EEE spreads and what you can do to reduce your risk of encountering it.
What is eastern equine encephalitis, or triple E?
Eastern equine encephalitis is a virus that is primarily transmitted by certain mosquitoes. It was first identified in horses that died of encephalitis along the mid-Atlantic coast in 1933. EEE was recognized to cause human disease during an outbreak involving horses and humans in southeastern Massachusetts in 1938.
Since then, sporadic human and horse cases have been reported nearly every year in the Atlantic, Great Lakes and Gulf Coast regions of the U.S., with larger outbreaks occurring several years apart in these areas. The last significant outbreak of human EEE disease was in 2019 when over three dozen cases were reported, largely from Massachusetts and Michigan.
Culiseta melanura mosquitoes feed almost exclusively on birds and usually do not bite humans or horses. However, more common mosquitoes such as Aedes, Coquillettidia and Culex can sometimes bite infected birds, become infected themselves and then transmit EEE virus to nearby humans or horses. These are called “bridging” mosquitoes.
Every few years, there are much larger outbreaks of EEE disease in certain areas. For instance, in 2019 over three dozen cases were reported, primarily from Massachusetts and Michigan. These cyclic outbreaks are likely due to a complex interaction between temperature, rainfall, mosquito populations, bird immunity and bird migration patterns.
EEE surfaces nearly every year in the U.S., but with another outbreak of West Nile virus also spreading across the country, health officials are working hard to alert people about the serious risks that come with getting a mosquito bite.
The Conversation asked Daniel Pastula, a neurologist and medical epidemiologist from the University of Colorado Anschutz Medical Campus, to explain how EEE spreads and what you can do to reduce your risk of encountering it.
What is eastern equine encephalitis, or triple E?
Eastern equine encephalitis is a virus that is primarily transmitted by certain mosquitoes. It was first identified in horses that died of encephalitis along the mid-Atlantic coast in 1933. EEE was recognized to cause human disease during an outbreak involving horses and humans in southeastern Massachusetts in 1938.
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