How many Maine ticks carry Powassan? We’re one step closer to finding out

Many Mainers first learned of the Powassan virus in 2013, when the illness claimed the life of a Rockland-area watercolor artist named Lyn Snow.

Lyn Snow

Lyn Snow

Her death, which followed a rapid decline in her health after a tick bite, has since fueled many questions about the virus.

With a new grant, Maine researchers will attempt to answer at least one of them: How many ticks in the state carry Powassan?

The Maine Outdoor Heritage Fund just awarded the Maine Medical Center Research Institute a $12,000 pilot study to conduct a statewide survey for Powassan virus, according Charles Lubelczyk, a vector ecologist at the institute. His team will collect ticks from across the state to test for the virus, providing a baseline for monitoring the prevalence of Powassan in the tick population going forward.

“We’d like to get at least a site in every county examined,” he said.

Charles Lubelczyk, a vector ecologist at the Maine Medical Center Research Institute

Charles Lubelczyk, vector ecologist at the Maine Medical Center Research Institute

Lubelczyk worked on earlier Powassan cases in Maine, when four people contracted the virus between 1999 and 2004. He remembers how the cases spurred him to vigilance — dressing appropriately in the field, checking himself for ticks and applying repellent. He and his team will take the same precautions as they head into the woods and fields of Maine for the pilot study, he said.

“We’re going to be dressed to the hilt,” Lubelczyk said.

As if Lyme weren’t bad enough, Powassan is, while rare, more often deadly. The virus can cause fever, headache, vomiting, weakness, confusion and seizures and may also lead to brain swelling, a devastating complication that kills 10 percent of those who develop it, according to the U.S. Centers for Disease Control and Prevention. About half of those who survive the infection suffer permanent neurological symptoms.

Ticks also appear to transmit Powassan much more quickly than Lyme. According to the CDC, ticks must be attached for at least 24 hours to transmit Lyme bacteria.

“With Powassan virus, a lot of initial studies show that the transmission time could be under an hour,” Lubelczyk said.

After Snow’s death, researchers met with her family and cobbled together a small amount of funding to test ticks in her area, he said. They didn’t find much, but the sample size was small.

Some areas of Maine are “hot” for Lyme — including southwestern Maine and into Kennebec County — and 40 to 60 percent of deer ticks in the state likely carry it, Lubelczyk said. He wants to see Maine gather the same information for Powassan.

Preliminary research in other New England states hints that 2 to 4 percent of ticks might harbor Powassan, he said. In Maine, Powassan has been found in deer and moose across the state.

The virus spreads in two strains, through the bite of both the deer tick — Lyme’s preferred host — and the woodchuck tick.

The woodchuck tick, formally known as Ixodes cookei

The woodchuck tick, formally known as Ixodes cookei

Another question researchers would like to answer: Can deer ticks carry both Lyme and Powassan at the same time? We already know the eight-legged parasites can harbor other infections, such as anaplasmosis and babesiosis, in addition to Lyme.

While confirmed cases of Powassan disease are few, the numbers are on the rise, according to the U.S. CDC.

“Folks are wondering how much of that went unrecognized previously,” Lubelczyk said. “No one knows the answer to that.”

Powassan virus neuroinvasive disease cases, 2004–2013

POWbyyear

Source: ArboNET, Arboviral Diseases Branch, Centers for Disease Control and Prevention.

 

While Maine has recorded no human cases of Powassan since Snow, the virus has cropped up in New Jersey, New Hampshire, New York, and Massachusetts.

Lubelczyk and his team will collect samples by dragging a cloth through the woods to catch ticks searching for a host on which to feed. You can nab ticks without even trying in York and Cumberland counties, but researchers will do some detective work to capture them in more northern counties.

To collect a broader sample, they’d also have to trap wildlife. Woodchuck ticks closely shadow the animals they feed on, which also include other rodents and small mammals, such as raccoons. The pilot study is too small to support trapping, but Lubelczyk hopes the data his team collects eventually feed into a broader project down the road, with more people power and intensive wildlife work.

“We’re pretty good at stretching and making things go on a shoestring budget,” he said.

Testing ticks for Powassan is much harder than for Lyme. Few labs conduct the testing because traditionally so few cases have arisen and because they must institute tighter biosafety protocols, like those used for West Nile virus and EEE, to handle Powassan, Lubelczyk said. More state labs, including Maine’s, are ramping up to test for the virus, he said, and the tick identification lab at the University of Maine will soon be equipped, after winning funding through a referendum last fall.

Lubelczyk’s team will ship ticks to Tufts University, where it’s working with Powassan researcher and vector-borne infections expert Sam Telford.

Lubelczyk is keen to develop an “entomologic risk index” for Powassan, which would gauge the risk of being bitten by tick nymphs versus adults. The tiny nymphs are responsible for most human cases of Lyme — people don’t spot and remove them as readily as the larger adults, he said.

A female deer tick (left) and a nymph deer tick. Courtesy of Griffin Dill, UMaine Cooperative Extension

A female deer tick (left) and a nymph deer tick. Courtesy of Griffin Dill, UMaine Cooperative Extension

But Lubelczyk hypothesizes that adult ticks skittering around later in the season could prove more critical in the fight against Powassan. Many people don’t realize ticks are still prevalent as adults in the fall — even into November — so public health campaigns may need to further spread the word, he said.

Adult ticks are more likely to carry pathogens and often latch on to our bodies longer than nymphs do, giving them more opportunity to pass along infections, he said.

“Because they’re older, they probably have twice as much chance of being infected as the nymphs do,” he said.

Jackie Farwell

About Jackie Farwell

I'm the health editor for the Bangor Daily News, a Bangor native, a UMaine grad, and a weekend crossword warrior. I never get sick of writing about Maine people, geeking out over health care data, and finding new ways to help you stay well. I live in Gorham with my husband Nick and our hound dog Riley.