What You Need to Know About the EEE Virus

Dr. Leonard A. Mermel, DO, ScM, AM (Hon), FSHEA, FIDSA, FACP is an infectious disease specialist with Brown Medicine’s Division of Infectious Diseases. He also is medical director of the Department of Epidemiology and Infection Control at Rhode Island Hospital and serves as professor of medicine at the Warren Alpert Medical School of Brown University.

Following is an excerpt from an interview with Dr. Mermel regarding the symptoms and risks of Eastern Equine Encephalitis:

Q: What is EEE?
A:  Eastern equine encephalitis is commonly called EEE for short. It’s an arbovirus, which is a group of viruses that are transmitted by mosquitoes or other arthropods. There are different geographic regions where the mosquito-borne viral infections were first discovered or regions where they are most likely to occur, such as Eastern, Western, LaCrosse, or St. Louis encephalitis. EEE is rare as there are only an average of 7 cases per year in the United States. However, there are already 7 cases in Massachusetts this year.

Mosquitoes that breed in Red Maple/White Cedar swamps transmit the virus to birds. Other mosquitoes then can spread the virus from those birds to mammals (human or horse, for example) by feeding on their blood.

Q: Why is it called equine? Can other animals get it, like dogs?
A: Horses spend their time outdoors and are at risk of contracting the virus from a mosquito feeding on their blood. However, the virus cannot be transmitted to other horses or people if a mosquito then feeds on the blood of an infected horse, nor will the horse transmit the virus to a human. Other animals at risk are pheasants, whooping cranes, turkeys, and emus. Canine infection are rare but can occur.

Q: Who is at risk for EEE?
A: Anyone who gets a mosquito bite in an area where EEE virus is found in mosquitoes may be at risk. Those who are out between dusk and dawn near Red Maple/White Cedar swamps are more likely to be exposed to mosquitoes that may be infected.

Q: Is anyone most at risk?
A: Generally those over 50 and those younger than 15 are most at risk of severe disease from an EEE viral infection. According to the CDC, one-third of those who develop the EEE viral infection will die, and many who survive will have mild to severe permanent neurological damage.

Q: Are there varying types of EEE viral infection?
A: Some people develop a systemic illness with nonspecific symptoms like fever, chills, muscle and joint pain lasting one to two weeks. Others can develop inflammation of the brain called encephalitis which can lead to coma and death. As noted above, severe infection is most common in those over 55 and younger than 15.

Q: What are the typical symptoms to be aware of?
A: The incubation period after a bite is 4-10 days. After that time, a person may present with general, nonspecific symptoms such as fever, chills, muscle and joint aches, and/or nausea. This may resolve in one to two weeks, but in some individuals, this may then progress to encephalitis.

Q: When should one seek medical attention?
A: People with a fever and flu-like symptoms should see their doctor because the cause could be something treatable such as strep throat, Lyme disease, anaplasmosis, babeosis, and with neurologic symptoms this could be due to bacterial meningitis or herpes encephalitis. Why suffer? If it’s treatable, your doctor can help make you better. Note that fever and severe headache and/or neck stiffness are danger signs requiring urgent medical attention such as at a hospital emergency department.

Q: How can one prevent getting EEE?
A: Take the usual precautions against mosquito bites including minimizing outdoor activities from dusk through dawn and wearing protective clothing and insect repellent.

Q: If caught early, does it make a difference? Is there a cure?
A: There is no generally agreed upon antiviral drug to administer to patients infected with EEE virus. However, specialized intensive care is important for those with encephalitis due to EEE virus.

For more information and real-time updates, visit:
Centers for Disease Control and Prevention: https://www.cdc.gov/
Rhode Island Department of Health: http://www.health.ri.gov/
Massachusetts Department of Public Health: https://www.mass.gov/orgs/department-of-public-health