A mosquito found in Edgartown has tested positive for West Nile virus, according to an announcement from the town’s board of health.
The mosquito was collected at the Edgartown Town Cemetery by Patrick Roden-Reynolds from the Massachusetts Department of Public Health, or MDPH, on behalf of the board as part of his Island-wide weekly surveillance trappings.
From the start of July to around mid-October, Roden-Reynolds sets six gravid traps across the six towns on Mondays, collects them the next day, and then sends them to the state laboratory. The laboratory sends back results by the end of the workweek.
The MDPH announced Friday, July 12, that the virus was detected in the insect.
There were no positive detections on-Island in 2023, and Roden-Reynolds said positive samples are rare.
West Nile virus was detected in mosquitoes in the same area in August 2022, and in West Tisbury in September 2022.
Roden-Reynolds takes a sample of about five or six mosquitoes, also called a pool, from each trap. Other places across the state test thousands. “It makes positives more meaningful, because we have a smaller sample size,” he said.
West Nile virus is a single-stranded RNA virus that can cause West Nile fever, and is typically transmitted to humans via mosquito bite. Symptoms of the virus include fever, headache, body aches, vomiting, diarrhea, or rash, though about one in five people show symptoms, according to the Centers for Disease Control (CDC).
About one in 150 people can develop serious, and sometimes, fatal illness, according to the CDC.
As of July 9, there have been 15 human disease cases of West Nile virus in the U.S. from 11 states this year. State public health officials announced the first West Nile virus–positive mosquito this year was found in two mosquito samples in Quincy on July 2. “Early detections might be indicative of a bad mosquito season,” Roden-Reynolds said.
Mosquitos that carry the disease can be found throughout the state, in both rural and urban areas.
There are currently no vaccines or treatments for the virus, and only through mosquito prevention can the virus be avoided.
The board of health cautioned those 50 years and older; the virus presents them with a higher risk of severe infection, though the virus can affect those of any age.
They recommend that people wear pants, long sleeves, and socks to mitigate mosquito contact as well as apply insect repellent with specific ingredients, such as DEET, permethrin, or picaridin, and lessen outdoors activities during peak biting hours: the hours from dusk to dawn.
To mosquito-proof a home, drain standing water, where mosquitoes lay their eggs, and install and repair screens to keep mosquitoes from getting indoors.
