BOSTON — The state Department of Public Health said Tuesday that it had confirmed the first case of West Nile virus in an animal this year. 

 

A goat was exposed to WNV in Lunenburg in Worcester County. The towns of Lunenburg, Leominster, Shirley, and Fitchburg are being raised to moderate risk.

 

"With this evidence of an animal infected with West Nile virus, we know that there are the right conditions and enough disease circulating to result in a human infection," said Public Health Commissioner Dr. Robbie Goldstein. "The elevated temperatures combined with high humidity increase mosquito activity. We want to remind people that there are easy ways to prevent mosquitoes from biting you, like using mosquito repellent when you are outdoors and being mindful of peak mosquito activity hours."

 

WNV is usually transmitted to susceptible animals and humans through the bite of an infected mosquito. The first evidence of WNV in mosquitoes in 2025 was announced on June 17, and 10 positive mosquito samples identified so far this year. There have been no human cases of WNV detected. There were 19 human cases of WNV in 2024 and no animal cases. No evidence of Eastern Equine Encephalitis (EEE) has been found so far this season. There were four human cases of EEE and three animal cases — all in horses — in 2024.

 

While WNV can infect people of all ages, people over the age of 50 are at higher risk for severe disease. Most people infected with WNV will have no symptoms. When present, WNV symptoms tend to include fever and flu-like illness. In rare cases, more severe illness can occur.

 

"Animals that live outdoors are at somewhat higher risk from arboviruses than humans who spend more time indoors," said State Epidemiologist Dr. Catherine M. Brown. "But the weather this summer is creating the opportunity for it to be a busy WNV season and it is important to take steps to prevent mosquito bites."

Avoid Mosquito Bites

 

Apply Insect Repellent when Outdoors. Use a repellent with an EPA-registered ingredient according to the instructions on the product label; note some repellents should not be used on children.

 

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 in areas of high risk.

 

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. Drain any standing water and change the water in birdbaths frequently and install or repair screens.

 

Protect Your Animals. Reduce potential mosquito breeding sites. Put horses in indoor stalls at night to reduce their risk of exposure and speak with veterinarians about mosquito repellents and vaccinations.

 

If an animal is suspected of having WNV or EEE, owners are required to report to the Department of Agricultural Resources, Division of Animal Health by calling 617-626-1795, and to the Department of Public Health by calling 617-983-6800.

 

 More information can be found here.