Public health officials warned Friday that eight Massachusetts communities are now at high risk for West Nile virus. The increased risk level applies to Boston in Suffolk County and Abington, Brockton, East Bridgewater, Marion, Mattapoisett, Rochester and Whitman in Plymouth County, according to the Department of Public Health. “We’re watching closely,” Boston Mayor Michelle Wu said. “For better or worse, we’ve been through this, so we have a monitoring mechanism and we’re in close contact with all the hospitals throughout the region and beyond.” The rest of Bristol, Norfolk and Plymouth counties, as well as parts of Barnstable, Berkshire, Essex, Hampden, Middlesex, Plymouth and Worcester counties, are considered at moderate risk, according to the Department of Public Health. The virus is usually transmitted to people through the bite of an infected mosquito. “The risk (of West Nile virus) is pretty widespread this year,” said Dr. Katherine M. Brown, state epidemiologist. “In addition to recommending the use of mosquito repellents containing EPA-registered active ingredients and clothing that reduces the amount of exposed skin, check window screens for holes and empty any containers around your yard that collect water.” According to the Massachusetts Department of Public Health, there have been six human cases of West Nile virus in 2023. There have been two confirmed human cases and no zoonotic cases so far this year. The first human case of 2024 was reported in Hampden County on August 6, and the second in Middlesex County on August 12. To date, a total of 262 virus-positive mosquito samples have been detected in Barnstable, Berkshire, Bristol, Dukes, Essex, Hampden, Middlesex, Norfolk, Plymouth, Suffolk and Worcester counties. The first positive sample was announced on July 2. “It is believed that if a person infected with West Nile virus is bitten 115 times and infected, only one person will develop symptoms,” said Dr. Todd Ellerin, chief of infectious diseases at South Shore Hospital. While most people do not become seriously ill from the virus, health officials say it can be dangerous for people with certain medical conditions, including cancer, diabetes, high blood pressure, kidney disease and people who have had organ transplants. These patients can develop a severe brain infection called encephalitis. Health officials are also concerned about the risk of another mosquito-borne disease, eastern equine encephalitis, a rare but serious and potentially fatal disease that can cause long-term physical and mental complications in survivors. In Plymouth, which is considered at high risk for EEE, city officials announced that starting Friday, all public parks and open spaces will be closed from dusk to dawn. Mosquito control spraying in these parks and open spaces will begin early next week. Mosquito control tips from MassDPH: Apply insect repellent when outdoors to avoid mosquito bites. Use insect repellents containing EPA-registered ingredients such as DEET (N,N-diethyl-m-toluamide), permethrin, picaridin (KBR 3023), or lemon eucalyptus oil (p-menthane-3,8-diol (PMD) or IR3535) according to product label directions. Do not use DEET products on infants under 2 months of age, and use no more than 30% on older children. Do not use lemon eucalyptus oil on children under 3 years of age. Be aware of the times of day when mosquitoes are most likely to bite. The hours between dusk and dawn are the most common time for many mosquitoes to bite. In high-risk areas, consider rescheduling outdoor activities to the evening or early morning. Clothing helps to reduce mosquito bites. Wearing long sleeves, pants, and socks outdoors helps keep mosquitoes away from your skin. Drain standing water to make your home mosquito-proof. Mosquitoes lay their eggs in standing water. Reduce the number of mosquito breeding sites around your home by draining or discarding objects that hold water. Check gutters and drains. Empty unused flower pots and watering pools, and change the water in bird baths frequently. Install or repair screens. Install tight-fitting screens on all windows and doors to keep mosquitoes out. Shelter animals Animal owners should reduce mosquito breeding sites on their property by eliminating standing water from buckets, tires, watering pools, and other containers, especially after heavy rains. Water tanks provide a perfect habitat for mosquito breeding, so they should be flushed at least once a week during the summer to reduce mosquito populations near pastures. Horse owners should keep their horses in indoor stalls at night to reduce the risk of mosquito bites. Also, consult with your veterinarian about mosquito repellents approved for use in animals, as well as preventative vaccines for West Nile virus and eastern equine encephalitis. If an animal is suspected to have West Nile Virus or Eastern Equine Encephalitis, owners should report it to the Department of Agricultural Resources’ Animal Health Section at 617-626-1795 or to Public Health at 617-983-6800.
Public health officials warned Friday that eight areas in Massachusetts are now at high risk for West Nile virus transmission.
According to the Public Health Department, this increased risk level applies to Boston in Suffolk County and Abington, Brockton, East Bridgewater, Marion, Mattapoisett, Rochester and Whitman in Plymouth County.
“We’re watching closely,” Boston Mayor Michelle Wu said. “For better or worse, we’ve already been through this crisis, so we’re watching closely and we’re in close contact with all the hospitals across the region and beyond.”
The risk is considered moderate for the remainder of Bristol, Norfolk and Plymouth counties, and parts of Barnstable, Berkshire, Essex, Hampden, Middlesex, Plymouth and Worcester counties, according to DPH.
The virus is usually transmitted to humans through the bite of an infected mosquito.
“The risk (of West Nile virus) is quite widespread this year,” said state epidemiologist Dr. Katherine M. Brown. “In addition to encouraging the use of mosquito repellents with EPA-registered active ingredients and clothing that limits exposed skin, be sure to check window screens for holes and empty containers of standing water around yards.”
According to the Massachusetts Department of Health, there have been six human cases of West Nile virus in 2023. So far this year, there have been two confirmed human cases, but no confirmed cases of zoonosis.
The first case of 2024 was reported in Hampden County on Aug. 6, and the second was reported in Middlesex County on Aug. 12.
To date, a total of 262 virus-positive mosquito samples have been detected in Barnstable, Berkshire, Bristol, Dukes, Essex, Hampden, Middlesex, Norfolk, Plymouth, Suffolk and Worcester counties. The first positive sample was announced on July 2.
“It’s believed that if someone infected with West Nile virus is bitten, only one of 115 will cause symptoms,” said Dr. Todd Ellerin, chief of infectious diseases at South Shore Hospital.
While most people who contract the virus do not become seriously ill, health officials say it can be dangerous for people with certain medical conditions, including cancer, diabetes, high blood pressure, kidney disease and those who have had organ transplants, which can lead to a severe brain infection called encephalitis.
Health officials are also concerned about the risk of another mosquito-borne disease, eastern equine encephalitis, a rare but serious and potentially fatal illness that can cause long-term physical and mental complications for survivors.
In Plymouth, which is considered high risk for EEE, city officials announced they would close all public parks and open spaces from dusk to dawn starting Friday, and mosquito control spraying in those parks and open spaces will begin early next week.
Mosquito safety tips from MassDPH:
Preventing mosquito bites
Use insect repellent when outdoors. Use repellents containing EPA-registered ingredients such as DEET (N,N-diethyl-m-toluamide), permethrin, picaridin (KBR 3023), or lemon eucalyptus oil (p-menthane-3,8-diol (PMD) or IR3535) according to product label directions. Do not use DEET products on infants under 2 months of age and use at a concentration of 30% or less on older children. Do not use lemon eucalyptus oil on children under 3 years of age.
Be aware of the times when mosquitoes are most prevalent. Dusk to dawn is when most mosquitoes are most likely to bite. If you are in a high-risk area, consider rescheduling outdoor activities to the evening or early morning.
Clothing can help reduce your risk of mosquito bites: Wearing long sleeves, long pants, and socks when you’re outdoors helps keep mosquitoes away from your skin.
Protect your home from mosquitoes
Drain standing water. Mosquitoes lay their eggs in standing water. Reduce mosquito breeding sites around your home by draining or discarding any standing water. Check gutters and drains. Empty unused flower pots and watering pools, and change the water in birdbaths frequently.
Install or repair screens: Install tight-fitting screens on all windows and doors to keep mosquitoes out.
Protecting animals
Animal owners should reduce mosquito breeding sites on their property by eliminating standing water in buckets, tires, wading pools and other containers, especially after heavy rains. Fish tanks are perfect breeding sites for mosquitoes, so they should be flushed at least once a week during the summer to reduce mosquito populations near pastures. Horse owners should keep their horses indoors in stalls at night to reduce the risk of exposure to mosquitoes. Also, talk to your veterinarian about mosquito repellents approved for use in animals and vaccines to prevent West Nile virus and eastern equine encephalitis.
If an animal is suspected to be infected with WNV or EEE, owners should report it to the Department of Agricultural Resources Animal Health Division by calling 617-626-1795 and to Public Health by calling 617-983-6800.
