Public health officials said Monday they are investigating a possible case of Powassan virus, a serious but rare tick-borne disease that has been on the rise in recent years, on Martha’s Vineyard.
The potential case comes during one of the worst tick seasons in New England in years, with a surge of tick-borne diseases and tick exposures. Only one case of Powassan virus has been recorded on Martha’s Vineyard in the past 20 years, officials said. So far this year, three cases have been confirmed in Massachusetts.
Powassan virus is spread to people by the bite of an infected tick and can be transmitted within just 15 minutes. Initial symptoms can include fever, headache, and vomiting. Severe cases can cause brain swelling, seizures, and long-term neurological complications. There are no vaccines to prevent or medicines to treat the virus.
Most cases occur in the Northeast and Great Lakes region from late spring through mid-fall, according to the Centers for Disease Control and Prevention. Powassan virus is carried by nymph and adult deer ticks.
“The virus is present every year in a small percentage of deer ticks; fortunately, severe disease remains very rare,” Dr. Sam Telford, a Tufts University professor who has conducted research on Martha’s Vineyard, said in a statement. Collaborating with the island’s tick program, his lab tested more than 3,500 nymph deer ticks between 2021 and 2024. Between 1 and 2 percent of deer ticks were infected, he said.
“This is a similar rate to that seen elsewhere in New England,” he said. “This suggests that many people who are exposed may successfully fight off the virus without ever knowing they were infected.”
Officials did not disclose the age of the resident, or when they might have been infected with the virus. But the Vineyard Gazette reported the virus was found in a 1-month-old from West Tisbury. The family of the infant said she has suffered brain damage from the infection but is currently listed as stable and is receiving treatment at Massachusetts General Hospital in Boston.
“We certainly had no idea a 20-minute walk on the West Tisbury bike path beside our home, a walk we do most every day, could potentially cause my child her life. Please, please, please check yourselves, your children and your pets. It was the tiniest nymph tick the size of a needle tip,” Tiffany Sisco and Marcus Sisco wrote in a Facebook post Saturday warning residents about the dangers of the virus. “Stay safe and cautious.”
“Lastly please continue the love and prayers for our sweet daughter Lily Sisco, she’s one hell of a fighter!” the family wrote, linking to a GoFundMe campaign to help pay for medical costs that has raised more than $20,000.
On the Vineyard, nymph deer ticks, the second life stage of ticks, are most active from May through July, Patrick Roden-Reynolds, the director of the island’s tick program, said in a statement.
“This makes nymph deer ticks the main driver of infectious diseases such as Lyme disease, babesiosis, anaplasmosis, borrelia miyamotoi, and Powassan virus,” he said. However, “adult deer ticks become active in the fall and remain so throughout the winter and early spring whenever temperatures exceed 40″ degrees.
Lea Hamner, contract epidemiologist for Dukes County, said preventing tick bites is the best protection.
Officials recommended taking steps including using EPA-registered tick repellents, treating clothing and gear with permethrin, an insecticide, wearing snug-fitting and light-colored clothing, and performing daily tick checks.
Shannon Larson can be reached at shannon.larson@globe.com. Follow her @shannonlarson98.
