Warm, Humid Weather Ramps Up Mosquito Population

PALMER — If you’ve been outside recently, you may have noticed that mosquitoes are out in full force. While some mosquito bites will only itch, others can carry potentially dangerous illnesses. For that reason, doctors with Baystate Health’s Eastern Region are encouraging people to be aware of the risk.

According to the Massachusetts Department of Public Health, more than 3,000 different species of mosquitoes have been identified worldwide, with more than 150 different kinds of mosquitoes found in North America. Fifty-one different kinds of mosquitoes have been found in Massachusetts. Mosquitoes are attracted to carbon dioxide, a gas that humans and other animals breathe out, and they can follow a stream of carbon dioxide from as far as 50 feet away.

Mosquitoes need stagnant water in order to lay their eggs — and not much of it. All a female mosquito needs is a bottlecap of water to lay 100 to 200 eggs. Once the eggs are laid, they hatch into larvae within 24 to 48 hours, so any temporary body of water that is present for more than a week can be a mosquito breeding habitat.

The diseases linked to mosquitoes locally are West Nile virus (WNV) and eastern equine encephalitis (EEE). While EEE is relatively rare in humans, there are occasional outbreaks in certain regions of the country. Fewer than 100 people have died from EEE in Massachusetts in the past 75 years, according to the Department of Public Health. In the U.S., approximately five to 10 EEE cases are reported annually. The risk of getting EEE is highest from late July through September, when more mosquitoes are present and active.

West Nile virus is a mosquito-carried virus most commonly spread to people through the bite of an infected mosquito. The majority of people who are infected with WNV will have no symptoms, while fewer than 20% will have symptoms such as fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands. Less than 1% of people infected with WNV will develop severe illness, including encephalitis or meningitis. There is no specific treatment for WNV infections.

The Department of Public Health recommends that people protect themselves and their loved ones from illnesses caused by mosquitoes by being aware of peak mosquito hours; applying insect repellent when outdoors; wearing long sleeves, long pants, and socks when outdoors; draining standing water around the home; and installing or repairing window and door screens.