Mosquitos aren’t just a summer annoyance; they can carry serious diseases. Basic precautions can help protect those most vulnerable to illness.
“We’re at the beginning of the mosquito season,” said Yale New Haven Hospital Infectious Disease Specialist Sunil Parikh, MD, MPH, associate professor of epidemiology at Yale School of Public Health. “They are obviously already out there biting but at least West Nile, it’s particularly in the dead of summer through early September when the greatest risk of human cases tends to happen.”
In the Northeast there are four main viruses that are most likely to appear. The most common is West Nile, accounting for roughly 200 documented cases in Connecticut. West Nile is caused by a particular species of mosquito that can feed on birds, picks up the virus and then transmits it to humans or other incidental hosts.
Essentially, the only way to get a mosquito-borne illness is through a mosquito bite, and it cannot be transmitted from human to human except in rare instances such as blood transfusions or organ transplants. Despite the correlation with birds, Dr. Parikh says there is currently no concern for mosquitos being a transmitter of bird flu.
The next most common virus is Eastern Equine Encephalitis (EEE). In 2019, there were four reported human cases in Connecticut, three of which were fatal. This virus is transmitted by a different kind of mosquito, and it can also affect horses. No human cases have been reported in Connecticut since then.
Two other viruses known to appear in the region are Jamestown Canyon and La Crosse virus, both of which are extremely rare. These viral infections can be serious but older adults, as well as those with underlying medical conditions are at a greater risk of getting seriously ill.
“When severe disease occurs, it is a neurologic disease. It's basically severe encephalitis or meningitis which includes headache and associated neurologic symptoms that can progress rapidly,” said Dr. Parikh. “That can include confusion, lethargy, decreased responsiveness and presenting in almost a coma like state.”
Other symptoms can include fever, nausea, and rash. If you believe you are experiencing symptoms related to a mosquito-borne illness, contact your primary care provider. There are no treatments, but symptomatic care can help. That’s why prevention is so important.
In 2023, four states confirmed locally-acquired malaria cases in the U.S. Although mosquitos known to transmit malaria are found in Connecticut, no locally-acquired cases have been reported here. Recently, the CDC warned that there is an increased risk of dengue infection in the U.S., another mosquito-borne virus. Currently, the risk for dengue in those living in Connecticut is through travel, and not from locally-acquired cases, though this situation could change in the future.
How to avoid mosquito bites
Dr. Parikh says the best way to avoid mosquito-borne illnesses is to follow the advice from the Connecticut Agricultural Experiment Station: follow the four “D’S”:
- Defend: Always use repellants when you’re outside, especially during peak mosquito season and when they’re most active in the morning and night. Products with DEET are considered safe to use, although they should be limited with children and babies. Instead, Dr. Parikh recommends using mosquito netting around strollers when possible.
- Dress: Dress in a way to help reduce your exposure to mosquitoes by wearing long pants and sleeves. When out hiking or in an area with lots of mosquitoes, tuck in pant legs. You can also treat clothing with permethrin, a substance that can help repel mosquitoes.
- Dusk/Dawn: These are the times when mosquitoes are most active. Limit your time outside during these times and be sure to use repellants and wear protective clothing if you are out early in the day or in the evening.
- Drain/Dump. Mosquitoes grow and reproduce in areas with standing water. They can lay eggs and develop in areas as small as a bottle cap. Go around your yard and dump out any standing water to reduce mosquito breeding.
What about having your yard sprayed for mosquitos?
“It's really a personal decision, but I think people need to think about the broader environmental impacts of spraying over such a wide area and what it can do to birds, other insects and wildlife that also live on that in that area,” said Dr. Parikh. “I think sticking to the four D's is a better idea.”
