The EEE virus is spreading in the US

A mosquito-borne virus is making a comeback: Eastern equine encephalitis (EEE). While not actually new, cases are extremely rare. Nonetheless, there have been higher instances than usual in the U.S. this year. If a case is severe, it has the potential to be deadly, and there is no cure or prevention for the disease. Illnesses like EEE are only going to become more common as the climate continues to warm.

What is EEE?

EEE has been spreading across the northeastern U.S. The virus is spread through mosquitos but is rare and deadlier than the West Nile virus. "Approximately 30% of people who develop severe eastern equine encephalitis die, and many survivors have ongoing neurologic problems," said the Centers for Disease Control and Prevention. "Definitely, I'd say New England and the Gulf Coast are the two areas in the U.S. where it's mainly occurred in the past," David Hamer, a professor of global health and medicine at the Boston University School of Public Health, said to The Hill. "Massachusetts has had hundreds of cases over a 70-year period," Hamer added. "There may not be any for a couple years, and then there's another case or two, although we believe that it may be occurring a little more frequently."

The good news is that most people do not experience symptoms. "In 95% of cases, the infection has no symptoms at all, and the person is really quite well and doesn't know they have the virus," Ruanne Barnabas, the chief of the Division of Infectious Diseases at Massachusetts General Hospital, said to The Hill. However, the virus creates a bad situation for people who do experience symptoms. "In 5% of cases, people do have symptoms, including fever and chills. And then it can actually affect the central nervous system, and they can develop confusion, abnormal movements and encephalitis as well." In the worst cases, EEE can lead to death. The disease also has no vaccines or medicines to prevent or treat it. Instead, people should protect themselves from mosquito bites by using insect repellant and wearing long sleeves.

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Will EEE get worse?

Along with people, the disease has also appeared in animals including horses, llamas and alpacas. Approximately 90% of horses infected with EEE have died. Dogs and cats are at much lower risk. The disease is not transmissible between animals and can only be passed through mosquitos in both humans and animals. It is also difficult to determine who is most at risk for severe EEE. "If you look at the cases, it seems to hit, you know, young teenagers, 30-year-olds, 40-year-olds — I mean healthy people that don't have clear risk factors. And so, I think everybody needs to be cautious," Hamer said.

The growing prevalence of mosquito-borne illnesses is largely due to climate change. Mosquitos thrive in warmer temperatures, and their range is rapidly expanding. Diseases like EEE are also appearing in regions where the diseases were not present before. "We've got milder winters, we've got warmer summers and we've got extremes in both precipitation and drought," Theodore G. Andreadis, a researcher who studied mosquito-borne diseases at the Connecticut Agricultural Experiment Station, said to Grist. "The impact that this has on mosquito populations is probably quite profound."