More ticks carry Lyme bacteria

By Emily Aronson and Shir Haberman
news@seacoastonline.com

PORTSMOUTH - The beautiful fall foliage is beckoning Seacoast area residents and visitors into local wooded areas, but this seemingly benign activity poses an increased danger this year.

Researchers at the University of New Hampshire and the Maine Medical Center Research Institute have discovered that an unexpectedly high percentage of black-legged ticks in New Hampshire are carrying the bacteria that cause Lyme disease in humans.

Research collaborators Alan Eaton, a UNH Cooperative Extension entomologist, and Eleanor Lacombe, of the Maine medical institute, analyzed 150 black-legged ticks collected recently in Durham, Lee and Concord for the presence of the bacteria.

"We found more than 50 percent of the ticks from Lee and Durham and more than 70 percent from the Concord sample infected with Lyme-causing bacteria," Eaton said. "Based on limited previous New Hampshire work, we’d expected only about 30 percent of the ticks would carry the bacteria."

Mid-October is the time of peak adult activity for the black-legged tick, the primary organism that spreads Lyme disease in New Hampshire, Eaton said. Tick season in the state’s woodlands will continue through December.

Charles Lubelczyk, a field biologist for the Maine medical institute, said part of the increase in Lyme disease cases noted in York and Cumberland counties is due to a proliferation of black-legged ticks, formerly known as deer ticks. Since hunting is being prohibited from more and more land, the deer herds in southern Maine are growing larger. This creates a perfect environment for the ticks, he explained.

"Migrating birds bring the ticks up from New Jersey and Connecticut," said Lubelczyk. "Larvae attach to these birds, as well as mice and chipmunks, and infection rates in mice and chipmunks are up in this area."

Dr. Jesse Greenblatt, New Hampshire’s state epidemiologist, said that over the past five years the state also has seen an increase in the number of Lyme disease cases.

"After sexually transmitted diseases, Lyme disease is the most commonly reported disease," he said.

Greenblatt added that he hasn’t yet seen Eaton’s study, but believes the data developed may be very helpful in making future recommendations on how the public can avoid the disease.

Lubelczyk described the increase in Lyme disease cases in Maine since 1988 as "significant," particularly in the areas from Kittery to Bar Harbor and inland to Bangor.

"There are a lot of projects taking place nationwide to deal with Lyme disease," the Maine field biologist said. "One is to remove deer completely. We tried that on an island in Maine, and it significantly decreased the occurrence of Lyme disease."

Lubelczyk also said experiments are under way involving spraying chemicals on mice, chipmunks and deer; he noted, however, that the side effects, such as wasting disease, can create other problems.

Nonetheless, Lubelczyk wasn’t optimistic about the likelihood that Maine and other states could stop the proliferation of ticks and the diseases they carry.

"We can look forward to increasing numbers," he said.

Still, Eaton and Greenblatt both suggested simple ways for people to protect themselves from coming into contact with infected ticks.

"People can reduce their chances of getting Lyme disease by tucking pant legs into socks before a trip into woods or fields, using insect repellent on socks and pant legs, and checking themselves thoroughly for ticks after a day outdoors," Eaton said.

Greenblatt, too, suggested that people who have been in wooded areas check themselves for ticks after coming home.

"Lyme disease is transmitted over many hours, so if you can get a tick that’s bitten you and get it off, you can avoid it," said the New Hampshire epidemiologist.

Eaton explained, "Because it takes 30 or more hours for a tick to infect you after it attaches to your body, doing a tick check every night before you go to bed will greatly reduce your chances of getting Lyme disease."

"An adult black-legged tick that’s just begun to feed will appear about size of a sesame seed, but it can reach the size of a large pea as it becomes engorged with your blood," Eaton added.

There are many other kinds of ticks in New Hampshire that don’t spread Lyme disease. The black-legged tick is the one people are most likely to find from mid-October through November.
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