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Published on October 07, 2016

Cape Cod ticks present a new health concern

Cape Cod ticks present a new health concern

A recent study showed that some deer ticks on Cape Cod are carrying the Powassan virus, which can be transmitted to humans. While a Powassan infection is potentially serious, in most cases people with infected with Powassan never show any symptoms, according to an expert in infectious diseases.

“It’s not a reason for people to be extremely worried,” said Patrick J. Cahill, MD, a physician in the infectious disease clinical service departments at Cape Cod Hospital and Falmouth Hospital. “It’s like the other viral encephalidities in that in the vast majority of cases, it’s sub-clinical. Most people are not even going to know that they have been exposed to it. It may play a role in some of the longer-term neurologic symptoms that have been traditionally blamed on Lyme.”

Larry Dapsis, entomologist and deer tick project coordinator with Barnstable County, collaborated with the Laboratory of Medical Zoology at UMass-Amherst this spring to look for the Powassan virus in deer ticks in six Cape Cod locations. Infected ticks were found in Falmouth, Brewster, Orleans and Truro. The percentage of ticks infected with the virus ranged from 2.5 to 10.5 percent, he said.

According to the federal Centers for Disease Control and Prevention, the signs and symptoms of Powassan infection can include:

  • Fever
  • Headache
  • Vomiting
  • Weakness
  • Confusion
  • Seizures
  • Memory loss

“There is no specific treatment for the virus,” said Dr. Cahill. “The treatment involves supportive care for symptoms.”

No Need To Panic

“While Powassan can be a very serious disease, we compare it to West Nile – serious but quite rare. Looking at the geographic distribution of the ticks, it suggests that Powassan has been on the Cape for some time, likely years,” said Dapsis. “What we do want the public to know is that we now have five tick-borne diseases associated with deer ticks, not four. It adds another dimension to the mix.”

The other tick-borne illnesses are Lyme disease, babesiosis, miyamotoi and anaplasmosis.

“It’s not just about Lyme anymore,” Dapsis said. “It reinforces our three-point message about prevention – protect yourself, protect your yard, protect your pets.”

The virus was discovered in 1958 in Powassan, Ontario. Since 2013, the Massachusetts Department of Public Health has received reports of nine cases of the virus in the state. The cases occurred in four counties, including Barnstable (the others were Middlesex, Essex and Norfolk Counties).

“It’s not something that we’re seeing, really, in our hospitals,” Dr. Cahill said. “As far as clinical infections, there have only been a handful reported in Massachusetts to date, going back as far as we’ve known about this disease.

“The fact that we’ve started to detect it in ticks around here likely means that it’s been pretty prevalent in ticks across the state for a number of years. Despite that, there have been less than 10 cases in the whole state, showing that overall most people are not affected by this.”

Powassan is “something for medical providers to keep in the back of their minds if somebody’s presenting with symptoms consistent with encephalitis [inflammation of the brain]. It’s something else that we have to evaluate them for in addition to things like West Nile, Lyme disease and Eastern equine encephalitis.” he added.

A Reminder to Protect Yourself

The discovery on the Cape of ticks with the Powassan virus is a good reminder to be careful about ticks in general, said Dr. Cahill.

Dapsis said that people should check themselves for ticks whenever they’ve been in wooded areas. He also recommended the use of tick repellants, including Deet-based products, or alternatives like picaridin, for exposed skin.

“In particular I recommend the use of permethrin on clothing and footwear,” he said. “Footwear is really important since the nymph-stage ticks are down in the leaf litter. In my experience, permethrin-treated clothing and footwear is the most effective tool in the box.”

Products containing permethrin, which should be applied on clothing and not the skin, can be found in major garden centers on the Cape, according to Dapsis.

He also suggested people consider a perimeter yard spray of tick repellant.

“You can either do it yourself or contract with somebody,” he said. “Research in Connecticut showed that 85 percent of the people who report getting tick bites got them from working around their own yards. If you have shade trees, bushes and leaf litter, you’re going to find ticks.”

For more information about tick precautions, read the OneCape Health News article “Protect yourself from tick-borne infections.”