Do most people bitten by infected mosquitos have no symptoms?

BOSTON – Dr. Mallika Marshall is answering your latest health questions. If you have a question, email her or message her on Facebook or X (formerly known as Twitter).
Jack writes, “I just read in an article on mosquito-borne diseases that 95% of people bitten by infected mosquitos have symptoms. Is that true?”
The two big mosquito-borne viral infections we worry about this time of year are West Nile Virus and Eastern Equine Encephalitis or EEE. Indeed, the majority of people who get infected with either of these viruses do not develop symptoms. Those few that do may have fever, body aches, headache, and fatigue and usually recover without complication.
However, a very small number of people can go on to develop neurologic disease such as meningitis or encephalitis which is inflammation of the brain. With West Nile, about 1 in 10 of these patients die. With EEE, it’s about 1 in 3. Unfortunately, there are no specific treatments for either so all we have to offer is supportive care with pain medication and intravenous fluids. And we can’t predict who will get severely ill and who will remain asymptomatic, so please do what you can to avoid mosquito bites.
Dr. Mallika is offering her best advice, but as always, consult your personal doctor before making any decisions about your personal health.