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A Mosquito-Borne Brain Virus Is Continuing To Kill People In The US


Tom Hale

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist


Colorized TEM micrograph of a mosquito salivary gland, with the virus particles colored in red. (83,900x magnification. Fred Murphy and Sylvia Whitfield/CDC

The number of fatalities rises further as cases of an untreatable brain-swelling virus continue to quietly appear around eastern areas of the US.

There have been 36 confirmed cases of eastern equine encephalitis – and at least 14 deaths – in the US this year, according to the latest statistics from the US Centers for Disease Control and Prevention (CDC). In a typical year, the CDC would expect to see just seven cases.


The last victim was Jim Whitright, a farmer from southwestern Michigan, who died on November 16 after falling ill in August, reports local news station WNDU.

Most of the cases have occurred in Massachusetts (12 cases) and Michigan (10), but there have also been odd reports from Connecticut, Indiana, North Carolina, New Jersey, Rhode Island, and Tennessee.

Eastern equine encephalitis, also known as EEE or Triple E, is characterized as a nasty illness that results in potentially deadly brain swelling. As a result, survivors of the disease are often left with permanent brain damage that can lead to severe intellectual impairment, personality disorders, and seizures.

Overall, just 4 to 5 percent of infections actually result in the development of full-blown EEE, although people over the age of 50 and under the age of 15 seem to be at greatest risk. Symptoms typically start with a headache, high fever, chills, and achy muscles. Some fortunate people will only experience these flu-like symptoms. However, the virus kills around one-third of the people it infects and leaves many survivors with ongoing neurological problems. 


Worst of all, it’s untreatable. There’s currently no human vaccine or specific antiviral treatment for EEE. 

The pathogen responsible for the disease is referred to as EEEV, a New World virus that infects birds, horses, humans, and a handful of other mammals. At least four lineages of the virus exist, with one endemic to North America and the Caribbean and the other three groups primarily occurring in horses in Central and South America.

The lifecycle and transmission of EEEV are particularly strange. The virus infects a specific species of mosquito known as Culiseta melanura, which generally only feeds on birds, infecting them in the process. Uninfected mosquitoes can also become infected by feeding on infected birds. However, to spread to humans, the virus requires other mosquito species, such as some Aedes and Coquillettidia species, to act as “bridge vectors” that pass the disease from infected birds to humans. 

Cases of EEE typically spike in the US around late summer and early fall. After this, frosts and cold weather cause mosquito activity to drop and the spread of infection starts to dwindle. However, if the weather remains warm and subzero temperatures aren't too common, the virus can continue to prosper much later into the year.  


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