Eastern Equine Encephalitis Virus

Last week a patient in New Hampshire who tested positive for eastern equine encephalitis virus died after being hospitalized with severe central nervous system diseases, according to a press release.

New Hampshire on Tuesday announced that a person in the state who tested positive for eastern equine encephalitis virus has died after being hospitalized with severe central nervous system diseases.

Between 2003 and 2018, the United States recorded an average of eight cases of eastern equine encephalitis per year. Last year, there were 38 cases of the mosquito-borne disease, including 15 deaths.

Eastern equine encephalitis, or EEE, is a serious disease of horses and, rarely, humans. However, there was an unusual and dramatic increase in human cases in the United States in 2019. Historically, the CDC reported 72 neuroinvasive cases in the U.S. from 2009 to 2018. During those 10 years, there was an average of seven cases of neuroinvasive disease each year, with a low of three in 2009 and a high of 15 in 2012. Most cases were reported from Florida, Massachusetts, Michigan, New York and North Carolina. In 2019, the human case number was five times higher than the average, with eight states involved (see Table). Some of the affected localities even cancelled outdoor activities to reduce the risk for becoming infected. It is unclear why the increase occurred and if it will continue in future years.

As of Oct. 22, 2019, there have been 35 confirmed cases of eastern equine encephalitis this year — a significant increase from the average of seven reported cases per year.