The first survey on Cape Cod for the tick-borne disease Powassan found ticks from Falmouth to Truro infected with the virus, which can attack the body’s central nervous system.
The highest infection rate was recorded in Truro, where 10.5 percent of ticks that were examined had the disease, said Larry Dapsis, an entomologist and deer tick program coordinator at the Cape Cod Cooperative Extension.
Dapsis said specialists were surprised by the percentage of infected ticks. “We didn’t think it would be that high,” he said.
Truro was among six sites where ticks were collected and tested for Powassan, Dapsis said. Some ticks taken from Brewster, Orleans, and Falmouth also carried the disease, suggesting the illness may have been in the region for a while, he said.
“This virus has been on the Cape probably for a number of years,” Dapsis said. “It’s probably flown under the medical radar screen.”
A study published in 1997 marked the first time Powassan was documented in New England, said Stephen Rich, professor of microbiology and director of the Laboratory of Medical Zoology at the University of Massachusetts Amherst. Rich collaborated with Dapsis on the spring inquiry and a smaller examination of the virus conducted last fall on Cape Cod.
Powassan is transmitted by the bite of a black-legged tick, also known as a deer tick.
Nine cases of the disease in people were reported to the state Department of Public Health between 2013 and 2015, said Dr. Catherine Brown, deputy state epidemiologist and state public health veterinarian. The cases were reported in patients in Essex, Norfolk, Middlesex, and Barnstable counties, and resulted in one death, she said.
Symptoms of Powassan resemble those found in people stricken with the mosquito-borne illnesses West Nile virus and Eastern equine encephalitis, Brown said.
Better-known diseases spread by ticks in Massachusetts include Lyme, babesiosis, and anaplasmosis, she said.
“Now, we have another disease that we need to be on the lookout for,” Brown said.
Medical evidence so far suggests Powassan may make some people severely ill while others could be infected and experience few symptoms, Brown said.
“We are only detecting the very sickest patients,” she said.
Symptoms of Powassan include fever, headache, vomiting, weakness, confusion, loss of coordination, speech difficulties, and seizures, according to a news release about the Cape Cod findings.
While there is no treatment for the disease, those stricken are advised to rest and drink fluids to prevent dehydration, the statement said.
Dapsis said he is seeking grant money to collect ticks from all 15 towns on Cape Cod and test them for Powassan. The spring inquiry cost about $15,000 and was paid for with Barnstable County funds, he said.
“We need more information,” Rich said. “We don’t know why one site is 0 percent and one is 10 percent.”
Dapsis said preventing tick bites is the best way to avoid contracting Powassan and similar diseases.
Checking skin for ticks, putting clothes in the dryer for 20 minutes to remove ticks, and using repellents registered with the US Environmental Protection Agency are some ways to avoid bites, the statement said.
“Our basic message to people is prevent getting the tick bite in the first place,” Dapsis said. “Protect yourself, protect your yard, and protect your pets.”Laura Crimaldi can be reached at firstname.lastname@example.org.