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Q&A: What PCPs should know about eastern equine encephalitis
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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.
The virus, known as EEE, is transmitted to humans through bites from infected mosquitoes. According to the CDC, approximately 4% to 5% of those infected with the virus develop EEE, and symptoms typically appear 4 to 10 days after being bitten.
About a third of EEE patients die, and many of those who survive have brain damage.
Eugene Shapiro, MD, a professor of pediatrics and epidemiology at Yale School of Public Health, spoke with Healio Primary Care about possible causes for the uptick in EEE cases and what PCPs should know about the virus. – by Erin Michael
Q: From 2014 to 2018, there were 32 confirmed cases of EEE, resulting in 11 deaths. So far in 2019, there have been 35 cases and 13 deaths. What could be causing the spike in cases?
A: It is uncertain, but there is normal yearly variation in incidence. If hard frosts that kill mosquitoes occur later in the year because of climate change, the mature mosquitoes — that have been alive longer and have had more blood meals and thus are more likely to become infected — persist longer and thus have more opportunity to transmit the infection.
Q: Could the increase in EEE cases in 2019 mean that there may be even more cases in 2020 and beyond?
A: Nobody knows — it is possible.
Q: So far in 2019, the virus has predominately affected states in the Northeast and Great Lakes regions. What might explain this trend?
A: Normal variation. The virus persists in a mosquito, Culiseta melanura, that thrives in swamps with cedar and red maple trees. Generally, these are present in those areas and along the Gulf Coast.
Q: What signs and symptoms of EEE should primary care physicians watch for?
A: None of the signs and symptoms of EEE are specific — fever, headache, nausea, vomiting. In the small proportion of patients who do go on to develop encephalitis, the large majority of those go on to develop coma. Diagnosis depends on specific IgM antibody in the cerebrospinal fluid.
Q: Once identified, what can be done to treat patients with EEE?
A: There is no specific treatment. Only supportive care is available. Supportive care is basically nonpharmacologic care that varies depending on what is needed, or even pharmacologic care that is not specific for EEE, such as antibiotics if they develop secondary bacterial pneumonia.
Q: What should primary care physicians tell patients worried about EEE?
A: The best way to prevent EEE is to prevent mosquito bites by avoiding being outdoors around dawn and dusk and by using mosquito repellent when outside in areas at which you are at risk of being bitten.
References:
CDC. Eastern equine encephalitis. https://www.cdc.gov/easternequineencephalitis/index.html. Accessed Oct. 30, 2019.
CDC. Eastern equine encephalitis: Frequently asked questions. https://www.cdc.gov/easternequineencephalitis/gen/qa.html. Accessed Oct. 30, 2019.
CDC. Eastern equine encephalitis: Statistics & maps. https://www.cdc.gov/easternequineencephalitis/tech/epi.html. Accessed Oct. 30, 2019.
Disclosure: Shapiro report no relevant financial disclosures.