Metro

Tick population may thrive thanks to snowpack’s insulation

This tick was collected by Rhode Island researchers.

JONATHAN WIGGS/GLOBE STAFF/FILE

This tick was collected by Rhode Island researchers.

Chalk up another strike against the winter. It turns out all that snow may have benefited one of our tiniest, but still-menacing, nemeses: the tick.

Rather than kill ticks, deep snow instead shields them from even more frigid air temperatures.

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Researchers say that could mean that there will be more ticks — which can carry Lyme and other diseases — out and about this summer, and more humans potentially infected.

“The deep snow likely served as an insulator, much to everyone’s chagrin,” said Thomas N. Mather, director of the University of Rhode Island’s Center for Vector-Borne Disease and its TickEncounter Resource Center.

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“In nature, these ticks have survived ice ages, so they’ve figured out how to get through even some of the coldest weather,” he added.

Although it’s still too early to know if this season’s tick population will be greater than normal — it’s still possible the recent arid weather may help mitigate a potential tick boom — public health officials are nevertheless warning outdoor adventurers to take precautions.

“Lyme disease is a huge problem here every year,” said Dr. Catherine M. Brown, Massachusetts public health veterinarian. “What we want to stress is prevention.”

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Officials at the TickEncounter Resource Center have kept tabs on this year’s tick population by monitoring the crowdsourced online submissions of photos and reports it collects from thousands of people around the country via its website, tickencounter.org.

Mather said that reports of American dog ticks in particular have been high.

“People are finding them in places they never have before, crawling inside their house . . . they’re everywhere,” he said.

Tick-borne illnesses in Massachusetts come from two species of the arachnid: dog ticks, which can carry some illnesses but are not known to carry Lyme disease; and deer ticks, also called black-legged ticks, which are known to carry Lyme disease.

It can be difficult to gauge the deer tick population based on crowdsourced reports because the ticks are smaller than dog ticks and less commonly encountered by humans, but Mather said early reports are that this population is high this year, too.

Ticks can be common not only in wooded areas, but also in rural and suburban locales including parks and yards.

Health experts say people should avoid areas where ticks are found, wear repellents, and check themselves and pets for ticks after being outdoors.

“People still sort of think about hiking in the woods as being the risk factor for tick-borne diseases,” said Brown. “[But] unless you’re in the middle of the concrete jungle, you need to be aware that there are ticks there.”

Lyme disease, which is the most common tick-borne illness locally, often causes flu-like symptoms and a rash that can take a bull’s-eye shape. If untreated, it can cause long-term problems, including cognitive issues and arthritis. The disease rarely causes death.

Reports of the disease have historically been concentrated in the Northeast and the upper Midwest.

In 2013, the US Centers for Disease Control and Prevention released preliminary results from research that estimated the number of Americans diagnosed with Lyme disease each year to be around 300,000, or about 10 times more than previous nationwide tallies showed.

Officials believe that many Lyme disease cases go unreported. Though officially reported figures represent only a fraction of all infections, the data can be used to monitor how the prevalence of the disease has changed over time.

Lyme disease rates in Massachusetts have risen in most years since the early 1990s, when there were only a couple hundred reported cases, according to figures collected by the state Department of Public Health. In 2013, the most recent year for which data are available, the state saw 4,080 confirmed cases and another 1,585 probable cases.

The totals were similar last year, according to Brown, who said 2014 numbers should be released soon. Increases in reported numbers here and elsewhere in the country have been attributed to factors including residential development expanding into wooded areas and better awareness and reporting of the disease.

Lyme disease is the most prevalent tick-borne illness in Massachusetts, Brown said. But ticks here have been known to spread two other illnesses in sizable numbers: anaplasmosis and babesiosis.

Both cause flu-like symptoms that can turn severe and, in rare cases, even fatal, particularly for the elderly or people with weakened immune systems. Treatment is available for both illnesses.

In 2008, there were just 41 cases of anaplasmosis and 51 of babesiosis. Last year there were 604 cases of anaplasmosis and 520 of babesiosis.

“We now really need to be thinking about these other diseases as well,” said Brown.

One very rare, but severe, tick-borne illness is called Powassan virus. There were just 75 cases nationwide between 2004 and 2013, including two in Maine and one in both Massachusetts and New Hampshire, according to the CDC.

Powassan symptoms include headaches, vomiting, confusion, seizures, memory loss, and long-term neurological problems, and it can cause death. There is no treatment.

Matt Rocheleau can be reached at matthew.rocheleau@globe.com. Follow him on Twitter @mrochele.
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