Mosquitoes and Health: How to Protect Your Family from the Pests

As the weather warms up, you'll see more mosquitoes. The tiny insects can be more than just an annoyance. While some mosquito bites will only itch, others can carry potentially dangerous illnesses, including easter equine encephalitis (EEE) and West Nile virus (WNV).

“It’s important to take steps to avoid mosquito bites,” said Dr. Joe Sills, chief of Emergency Medicine for Baystate Medical Center. “Some mosquitoes carry germs that can make people and some animals sick. In Massachusetts, the diseases linked to mosquitoes are West Nile virus (WNV) and eastern Equine Encephalitis (EEE) virus. Most people won't experience symptoms from either virus, but there are important differences to be aware of.”

Where Do Mosquitoes Live?

According to the Massachusetts Department of Public Health, there are over 3000 different kinds, also called species of mosquitoes 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.

Only female mosquitoes bite to suck blood and use the blood to make eggs.

How Mosquitos Spread Through Massachusetts

Mosquitoes need stagnant water to lay their eggs. What most people don't realize is the surprising number of areas around their own house where mosquitoes can find the stagnant water they need.

"All of the rain that has pooled in birdbaths and toy buckets during the past week is about to yield a bumper crop of mosquitoes," said Dr. Robert Spence, chief of emergency medicine for Baystate Wing Hospital. “Any temporary body of water that is present for more than a week can be a mosquito breeding habitat. Even flooded tire tracks and footprints in a muddy field have been known to produce dozens of mosquitoes each."

All a female adult mosquito needs is a bottle cap 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.

Why Are Mosquito Bites so Itchy?

Even if you don’t end up getting a mosquito-borne illness, having arms and legs covered in mosquito bites isn’t the best way to spend your summer either.

Many people find mosquito bites itchy. This happens because the mosquito injects you with its saliva while it’s sucking your blood.

People have different degrees of reactions. Red, itchy bumps are a common symptom. The symptoms can last hours or several days, depending on the person.

Some severe symptoms of a mosquito bite include:

• A large area of swelling and redness
• Fever
• Hives
• Swollen lymph nodes

A very small percentage of the population has Skeeter syndrome, which is a severe allergy to mosquito bites. Symptoms include swelling and fever within a few hours of the bite.

How to Treat a Mosquito Bite

If you scratch the mosquito bite, it can become infected. Infected bites look red and feel warm. You may need to see a doctor if it gets worse. Infected bites can leave a scar once they heal.

If you get an itchy mosquito bite, you should instead:

• Wash the bite with soap and water
• Put an ice pack on the spot for ten minutes
• Put on anti-itch cream

The CDC also has a home remedy (using baking soda and water) you can try.

Mosquitoes Can Spread Disease

"Some mosquitoes carry germs that can make people and some animals sick,” Dr. Spence said. “In Massachusetts, the diseases linked to mosquitoes are West Nile virus (WNV) and eastern equine encephalitis (EEE) virus."

What is Eastern Equine Encephalitis (EEE)?

EEE is relatively rare in humans, although there are occasional outbreaks in certain regions of the country. Outbreaks of EEE usually occur in Massachusetts every 10 to 20 years. These outbreaks will typically last two to three years. The most recent outbreak of EEE in Massachusetts began in 2019 and included twelve cases with six fatalities. The outbreak continued in 2020 with five cases including one fatality. The risk of getting EEE is highest from late July through September when more mosquitoes are present and active.

“It is possible that some people who become infected with mosquito-borne viruses may not develop any symptoms or in some cases only flu-like symptoms,” said Dr. Sills. “The incubation period for the virus from the time of an infected mosquito bite to onset of illness ranges from four to ten days and the illness can last one to two weeks. There is no specific treatment for EEE. Antibiotics are not effective against viruses, and no effective anti-viral drugs have been discovered for the treatment of EEE,” said Dr. Sills. “Severe illnesses are treated by supportive therapy, which may include hospitalization, respiratory support, IV fluids and prevention of other infections.”

What is West Nile Virus (WNV)?

WNV is a mosquito-carried virus most commonly spread to people through the bite of an infected mosquito. Because most people who are exposed to WNV have no symptoms, it is difficult to know exactly how many people have been infected. People who develop severe illness with WNV are most often reported. Between 2014 and 2023, 131 people were reported with WNV infection in Massachusetts. Eight of these people died. Cases have been identified from around the state.

“The majority of people who are infected with WNV (approximately 80%) will have no symptoms,” said Dr. Sills. “A smaller number of people who become infected, less 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,” said Dr. Sills. “People with mild WNV infections usually recover on their own. People with severe WNV infections almost always require hospitalization.”

Can You Cure Mosquito-Borne Illnesses?

Antibiotics are not effective against viruses.

No effective anti-viral drugs have been discovered for the treatment of EEE. Severe illnesses are treated by supportive therapy, which may include:

• Hospitalization
• Respiratory support
• IV fluids
• Prevention of other infections

There is no treatment for WNV. While they will have a full recovery, people infected with WNV may feel weak and fatigued for weeks to even months.

“People with mild WNV infections usually recover on their own. People with severe WNV infections almost always require hospitalization,” Dr. Spence said. 

How to Protect Yourself and Your Family from Mosquito Bites

Dr. Sills encourages community members to follow the Department of Public Health tips that will help people protect themselves and their loved ones from illnesses caused by mosquitoes. Try these mosquito control tactics:

• Be aware of peak mosquito hours: The hours from dusk to dawn are peak biting times for many mosquitoes. Consider rescheduling outdoor activities that occur during the evening or early morning.
• Apply insect repellent when outdoors: Use a repellent with DEET (N, N-diethyl-m-toluamide), permethrin, picaridin (KBR 3023), oil of lemon eucalyptus [p-methane 3, 8-diol (PMD)] or IR3535 according to the instructions on the product label. DEET products should not be used on infants under two months of age and should be used in concentrations of 30% or less on older children. Oil of lemon eucalyptus should not be used on children under three years of age.
• Clothing can help reduce mosquito bites: Wearing long sleeves, long pants, and socks when outdoors will help keep mosquitoes away from your skin.
• Mosquito-proof your home and drain standing water: Mosquitoes lay their eggs in standing water. They can begin to multiply in any puddle or standing water as small as a bottle cap that lasts for more than four days. If you have a bird bath in your yard, be sure to empty it daily and refill it with fresh water. Remove containers that may hold water in places that are hard to see such as under bushes, porches, decks, or stairs.
• Drill holes in the bottom of recycling containers that are left outdoors so that water can drain out.
• Clean clogged roof gutters; remove leaves and debris that may prevent drainage of rainwater.
• Turn over plastic wading pools and wheelbarrows when not in use.
• Change the water in birdbaths every few days; aerate ornamental ponds or stock them with fish.
• Install or repair screens: Keep mosquitoes outside by having tightly fitting screens on all of your windows and doors.

DEET is toxic to pets. To protect your dog or cat from mosquitoes, look for something pet-safe like citrus juice or naturally mosquito-repelling plants.

Learn more about controlling the mosquito population outside your home and getting rid of mosquitoes inside