State health officials recently detected West Nile virus in mosquitoes in Massachusetts, including the Boston area, marking the beginning of mosquito season surveillance. While that may sound alarming, the presence of the virus doesn't mean everyone who gets a mosquito bite is at risk of becoming sick. There's no need to stay indoors all summer. A few simple precautions can help protect you from mosquito bites while you continue to enjoy everything the season has to offer.
"The vast majority of people who are infected with West Nile virus never become seriously ill," says Tine Vindenes, MD, MPH, Division Chief, Geographic Medicine and Infectious diseases at Tufts Medical Center and Assistant Professor of Medicine at Tufts University School of Medicine. "The goal is to reduce your risk of mosquito bites, especially during the months when mosquitoes are most active."
What is West Nile virus?
West Nile virus is spread through the bite of an infected mosquito. Mosquitoes become infected after feeding on infected birds, which serve as the virus's natural reservoir. The virus is not spread from person to person through casual contact. You can't catch it from someone who is sick.
Most West Nile virus activity occurs during the summer and early fall, when mosquito populations are at their highest. Health officials monitor mosquitoes throughout the season to identify where the virus is circulating and to help communities understand their level of risk. West Nile virus activity can change throughout the season; take a look at this map to monitor the risk in your area.
What are the symptoms?
Most people who are infected with West Nile virus never develop symptoms. When symptoms do occur, they usually appear within a few days to two weeks after a mosquito bite and may include:
- Fever
- Headache
- Body aches
- Fatigue
- Nausea or vomiting
- Occasionally, a skin rash
Most people recover on their own with rest, fluids and time.
In rare cases, the virus can affect the brain or nervous system, causing serious illness. Older adults and people with weakened immune systems are at higher risk for severe disease.
Simple ways to avoid mosquito bites
Protecting yourself from West Nile virus is possible in a few easy steps:
Use insect repellent
Choose an EPA-registered insect repellent containing ingredients such as DEET, picaridin or oil of lemon eucalyptus. Follow the directions on the label, especially when applying repellent to children.
Cover up when mosquitoes are most active
Mosquitoes that spread West Nile virus are often most active around dusk and dawn. If you'll be outside during those times, wear long sleeves, long pants and socks whenever it's practical.
Remove standing water around your home
Mosquitoes lay their eggs in standing water. Once a week, empty or refresh water that collects in places like:
- Flower pots
- Bird baths
- Buckets
- Children's toys
- Trash cans
- Gutters
Even small amounts of water can become breeding sites.
Keep mosquitoes outside
Repair window and door screens so mosquitoes can't get indoors. If you're spending time on a porch or patio, consider using a fan. Mosquitoes are weak fliers and have a harder time landing when air is moving.
When should you call a doctor?
Most mosquito bites are nothing more than an itchy nuisance. If you develop fever, severe headache, confusion, weakness, difficulty walking or other concerning symptoms after spending time outdoors, contact your healthcare team promptly. While serious illness from West Nile virus is uncommon, early evaluation is important.
"Most mosquito bites don't lead to West Nile virus," says Dr. Vindenes. "But if you develop symptoms that concern you, especially if they become severe or don't improve, it's always worth checking in with a clinician."
Don't let mosquitoes keep you inside
The risk of West Nile virus is real, but it remains low for most people. The simple habits that help prevent mosquito bites—using repellent, wearing protective clothing and eliminating standing water around your home—can dramatically reduce your risk. There's no reason to avoid your favorite summer activities. A little preparation can help you enjoy the season while staying healthy.
Feeling under the weather?
Try the Tufts Medicine Symptom Checker to better understand your symptoms and learn when it's time to see a clinician.
If you're feeling ill after a mosquito bite or have symptoms that concern you, a Tufts Medicine primary care clinician can help determine whether you need further evaluation or treatment.
