Public Health Situation Alert - West Nile Virus
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Berkshire County, MA |
August 1, 2026 |
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Public Health Situation Alert – West Nile Virus |
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West Nile Virus (WNV) Positive Mosquitoes Identified Again. Massachusetts Department of Public Health (DPH) has collected WNV positive mosquitos in Clarksburg, Lanesborough, Pittsfield, and two days ago in Becket. So far there have been no human cases of WNV reported in Massachusetts. With the recent rain, standing water and heat, more mosquitoes are likely soon. Why is WNV a problem? WNV can cause illness ranging from a mild fever to more serious disease like encephalitis (swelling of the brain) or meningitis (inflammation of the covering of the brain and spinal cord). It was first identified in the United States in 1999. Between 2001 and 2025, 273 people were reported with WNV infection in Massachusetts. Twenty of these people died. What are the symptoms? Most people who are infected with WNV (80%) will have no symptoms. A smaller number of people who become infected (20%) will have symptoms such as fever, headache, body aches, nausea, vomiting and sometimes swollen lymph glands. They may also develop a rash. Less than 1% will develop severe illness including encephalitis or meningitis. Symptoms of severe illness can include high fever, headache, neck stiffness, confusion, tremors, seizures/convulsions, muscle weakness, vision loss, numbness and paralysis. People older than 50 years of age have a higher risk of developing severe illnesses. How is WNV transmitted? Mosquitoes become infected when they feed on infected birds. Infected people cannot transmit the disease to others, except in the rare instances of pregnant or breast-feeding people passing it to their babies, through blood transfusions or organ transplants, or through direct contact with infected body fluids from injured birds. What precautions should I take? Remove all stagnant/standing water on your property (birdbaths, wading pools, clogged gutters, tires, catch basins, etc.), make sure window and door screens are repaired and tight, avoid being outside when mosquitoes are most active (dusk to dawn), use an EPA registered mosquito repellant whenever mosquitos are present, wear long pants, long-sleeved shirts and socks. Prevention is always the safest strategy. Event organizers and Recreational Camps for Children should keep prevention in mind when scheduling events during peak mosquito season which is now. Where can I get more information? West Nile Virus (WNV) | Mass.gov Massachusetts arbovirus update | Mass.gov Mosquito-borne Diseases | Mass.gov West Nile: Causes and How It Spreads | West Nile Virus | CDC
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More Information: [email protected] What is West Nile virus?West Nile virus (WNV) is a virus carried by mosquitos that can cause illness ranging from a mild fever to more serious disease like encephalitis (swelling of the brain) or meningitis (inflammation of the covering of the brain and spinal cord). It was first identified in the United States in 1999. How is West Nile virus spread?WNV is most commonly spread to people through the bite of an infected mosquito. Less commonly, it can be spread through blood transfusions or organ transplants. All donated blood in the United States is tested for WNV. In addition, there are rare reports of WNV being passed from infected pregnant or breastfeeding people to their babies. Since these reports are rare, the health effects on unborn or breastfeeding babies are unclear and still being studied. People do not become infected by having direct contact with other infected people, birds or animals. Why don’t I need to report dead birds anymore?From 2000 to 2008, MDPH collected reports and ran tests for WNV on dead birds in Massachusetts as one of several ways to monitor WNV activity across the state. This method has become less useful for finding the virus. Many other states have discontinued dead bird reporting and testing. Mosquito collection and testing gives the most reliable indication of current WNV activity and this is where monitoring activities will continue to be focused. Dead birds are no longer being tested for WNV and do not need to be reported to MDPH. Dead birds can be safely disposed of in the trash. Using gloves, a shovel or plastic bags covering your hands, the dead bird should be double-bagged and placed in the trash. You should then wash your hands. What are the symptoms of West Nile virus?Most people who are infected with WNV (80%) will have no symptoms. A smaller number of people who become infected (20%) will have symptoms such as fever, headache, body aches, nausea, vomiting and sometimes swollen lymph glands. They may also develop a rash. Less than 1% will develop severe illness including encephalitis or meningitis. Symptoms of severe illness can include high fever, headache, neck stiffness, confusion, tremors, seizures/convulsions, muscle weakness, vision loss, numbness and paralysis. Persons older than 50 years of age have a higher risk of developing severe illness. How soon do symptoms of West Nile virus appear?Usually 2-6 days (but up to 30 days) after being bitten by an infected mosquito. It can take longer in immunocompromised individuals. How common is West Nile virus in Massachusetts?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 2001 and 2025, 273 people were reported with WNV infection in Massachusetts. Twenty of these people died. Cases have been identified from around the state.How is West Nile virus diagnosed?Serum (a component of blood) or cerebrospinal fluid (CSF) can be collected and tested for antibodies against the virus or for viral genetic material. How is West Nile virus treated?There is no specific treatment once infection with WNV has occurred. Treatment consists of supportive care, rest, and fluids to prevent dehydration. How can you prevent West Nile Virus?Preventing mosquito bites is the best way to prevent WNV infection. Here are some things you can do to reduce your chances of being bitten:
Where can I get more information on West Nile virus?
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