Deer tick virus lurks in some Vineyard ticks

Edgartown man didn’t get sick even though bitten by virus positive tick.

A magnified underside photograph of an adult female woodchuck tick (ixodes cookei), the kind of tick blamed for transmitting Powassan virus. — Courtesy Maine Medical Center Research Institute

Two years ago this November, upon rising from bed after a hunting trip at Spring Point in Chilmark, 53-year-old Edgartown resident Karl Nelson found a tick attached to his lower right leg. Nelson estimated the tick was there for more than 12 hours before he removed it. He sent the tick off to the Laboratory of Medical Zoology at the University of Massachusetts Amherst for TickReport testing.

The tests came back positive for Powassan.

UMass tick expert Steve Rich, director of the laboratory, later told The Times, with Nelson’s permission, that the tests actually indicated deer tick virus, a close relative of Powassan.

Borrelia burgdorferi, the microbe that causes Lyme disease, is estimated to need a day and a half to two days to transmit through an attached tick.

“Unlike other tick-borne diseases, a tick can transmit POW virus while being attached to a person for as little as 15 minutes,” the New York State Department of Public Health reports.

Deer tick virus is a strain of Powassan virus, and, according to the Centers for Disease Control, about half the survivors of symptomatic infections suffer permanent neurological damage.

“I waited and hoped I wouldn’t get any symptoms,” Nelson told The Times. Ultimately, he didn’t.

“Although most people who are exposed to Powassan virus likely never feel ill, others may become severely ill with meningitis (inflammation of the covering of the brain and spinal cord) or encephalitis (inflammation of the brain),” the Massachusetts Department of Public Health website states. Signs and symptoms include fever, headache, vomiting, weakness, confusion, loss of coordination, speech difficulties, and seizures.

The CDC notes that 10 percent of infections that result in encephalitis are fatal.

“Deer tick virus is considered to be a subtype of Powassan virus, so a lot of people use just Powassan to refer to both,” tick expert Sam Telford, a professor of disease and global health at Tufts University, wrote in an email to The Times.  “We know both can cause severe disease. The operative word is ‘can.’ Exposure does not equal transmission, let alone infection; infection does not necessarily translate into disease. The closely related West Nile virus has a high asymptomatic ratio… 80 percent of those who are infected are completely asymptomatic…only 20 percent have fever and of those only 1 percent get encephalitis.  We suspect Powassan/deer tick virus is very similar.”

As Telford told an audience at the Edgartown Library last year Powassan and deer tick virus are differentiated only by minute variances in their RNA.

Well known to Islanders, the deer tick not only transmits Lyme but also its namesake, deer tick virus, a pathogen Telford named. He was also part of the research team to first identify the virus in 1996.  

Dukes County tick biologist Dick Johnson told The Times the Vineyard has a bumper crop of deer ticks this season, especially up-Island.

“It’s pretty bad up in Chilmark. We’re finding a lot,” he said.

He described Chilmark and Aquinnah as “both pretty horrific when it comes to deer ticks.”

Chris Kennedy, Vineyard stewardship manager for the Trustees of the Reservations, said Chappaquiddick is equally rampant with deer ticks. He described deer ticks as of “primary concern for most of our visitors.”

Kennedy, who lives on the Wasque conservation area, said deer ticks have begun to rival the ever-numerous dog ticks.

“On Chappy we’re now finding as many deer ticks on [our] dogs as the dog ticks,” he said.

Kennedy’s work regularly puts him in tick habitat but unlike in seasons past, he’s managed to elude illness so far.

“Normally I’ve been on doxycycline twice by this time of year,” he said.

Eventually all Trustee’s rangers wind up taking doxycycline, he pointed out.

While an important medicine to combat Lyme, as an antibiotic, doxycycline has no effect on either form of Powassan. As the CDC notes, there are no available vaccines for Powassan nor are there any treatment medications.

To underscore the volume of ticks on Chappaquiddick, Kennedy said last week a Trustees ranger was carpeted with ticks on Cape Poge while walking down a path in heavy brush.

“Upwards of a hundred — mix of lone star and deer ticks,” he said.

The ranger was sent home to shower and do a tick check, he said, and so far she’s okay.

True Powassan, as opposed to deer tick virus, hails from the woodchuck tick, not the deer tick, according to the CDC. Though it has also been found in the squirrel tick, the CDC notes.  

It is not transmitted by deer flies, mosquitos, lice, or fleas, according to Telford.

Johnson has yet to happen on woodchuck ticks in his field studies. “I’ve never seen them,” he said.

Telford previous told The Times woodchuck ticks are mostly encountered near the burrows of the mammals they feed on like skunks, foxes, raccoons, dogs and cats. He said he has examined the brain matter of scores of Island mammals favored by the woodchuck tick and found no evidence of true Powassan on-Island as opposed to deer tick virus.

Chuck Lubelczyk, a vector ecologist at the Maine Medical Center Research Institute, described Powassan/deer tick virus as “not as universal as the pathogen that causes Lyme disease. In Maine, Institute researchers found five spots, from Midcoast to the New Hampshire border, where the virus showed up in ticks. In many other spots it did not show up at all, he said. What the spots had in common was they had “robust” tick populations in general. At the five spots, the infection rate was between 1 percent to 3 percent.

The death of a prominent watercolor artist brought Powassan/deer tick virus to the institute’s doorstep.

Marilyn Ruth Snow visited her local hospital on Nov. 9 with a tiny, stubborn tick embedded in her shoulder blade,” the Bangor Daily News reported on Dec. 24, 2013.

“Two days later, the active and healthy 73-year-old, a Rockland area watercolor artist better known as Lyn, would speak her last coherent words with her family.

“After that she became delirious and she was in and out of consciousness,” said her daughter Susie Whittington. “Then she was gone.””

“That case in 2013 really opened our eyes up,” Lubelczyk said.

“[The woman] was treated for presumptive Lyme disease but then went downhill fairly quickly after that,” Telford wrote in an email.  “Although CDC determined that the woman had antibod[ies] to Powassan virus, it was our lab that definitively identified the culprit as deer tick virus because there is no way to discriminate between classical Powassan virus and deer tick virus using antibody tests because the two viruses are closely related.”

Telford went on to write Maine Medical Center sent him autopsy material with the family’s permission.   

“We found that mice that were inoculated with the material developed antibodies (but not active infection) and my wife, who is the molecular biology expert, was able to sequence the virus from the autopsy material, definitely proving that it was deer tick virus and not Powassan virus (they differ genetically).”

Between 2013 and 2016 there were 14 known cases of Powassan on Cape Cod, according to entomologist Larry Dapsis, Barnstable County tick project coordinator. Of those, three were fatal, he said. The deceased were older males, he said. Dapsis said it was “very unlikely” any of the ticks that transmitted the virus to those affected on the Cape were woodchuck ticks. He said he believes deer tick virus was at play in all the cases, stemming from deer tick bites.

Telford said the young, old, and immune compromised are most at risk from the virus.

“These groups can suffer severe disease but most others can likely ‘hold it at bay’,” he said.

“Since 2013 we’ve been seeing 1-3 cases a year in Maine,”  Lubelczyk said. “I think most of them have been middle age and older. So far we’ve not had any case in the summertime when nymphal ticks are out.”

Lubelczyk said it’s deer tick females (and he suspects woodchuck tick females too) that have plastic bodies and are able to expand as they take in a blood meal. Nymphs can too but at that stage of life they are genderless, he pointed out.

“Males have a very rigid body,” he said and can’t in-take much, if any blood. Their primary purpose is to meet up with female ticks to mate, he said.

Lubelczyk said it’s likely only females and nymphs transmit disease.

As The Times reported in May, Richard Ostfeld, distinguished senior scientist at the Cary Institute of Ecosystem Studies in Millbrook, N.Y., considers Powassan/deer tick virus worse than even Rocky Mountain spotted fever, which Telford described as a “real killer.”

“Powassan and deer tick virus have been around in the environment for a very long time,” Telford wrote. “One of our current research projects is to try to understand why we are starting to see more cases.  One key influence is that Americans are aging (there are more 60+ out there) and there are more immunocompromised people around. So it is not necessarily that these infections are increasing in nature, but that the population of susceptibles is now different than what it was 10 or 20 years ago.”

Rich told The Times a survey his UMass lab conducted on the Vineyard

“found sites that were close to 10 percent Powassan positive.”

Rich later emailed, “[W]hile Powassan type 1 is found mostly in woodchuck ticks now, historically it was found in many different species including those like dog ticks.”

While Nelson counts himself lucky for not contracting deer tick virus, Nelson said he suffers from chronic babesiosis, a rare protozoan ailment transmitted from another tick bite. Nelson said he’s dealt with the disease for eight years and has been largely asymptomatic for seven years.

“I still test positive for it and my red blood cell count is below normal — extremely low,” he said.

Telford encouraged Islanders and Vineyard visitors, to protect themselves from ticks through use of permethrin, “not to panic about a tick bite” and to enjoy being outside.



  1. Excellent article and a greatly needed public health commentary. I suggest we import as many animals as possible that eat ticks. Yes, it may create other problems, but it seems Lyme disease is far worse.

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