50 percent to 70 percent of local ticks infected

Scientists have discovered that an unexpectedly high percentage of blacklegged ticks in New Hampshire carry the bacteria that cause Lyme disease in humans.

Research collaborators Alan Eaton, a University of New Hampshire Cooperative Extension entomologist, and Eleanor Lacombe of Maine Medical Center Research Institute, analyzed 150 adult blacklegged ticks collected 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,” said Eaton. “Based on evidence from previous, but limited, research in New Hampshire , we expected only about 30 percent of the ticks would carry the bacteria.

“These are preliminary data, and we need to do more work to get a complete picture of the Lyme disease risk in New Hampshire ,” cautioned Eaton.

“Mid-October is the time of peak adult activity for blacklegged tick, the primary organism that causes Lyme disease in New Hampshire ,” Eaton said. “People can reduce their chances of getting Lyme disease by tucking pantlegs into socks before a trip into woods or fields, using insect repellant on socks and pantlegs, and checking themselves thoroughly for ticks after a day outdoors”

“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 so will greatly reduce your chances of getting Lyme disease,” said Eaton. “An adult blacklegged tick that’s just begun to feed will appear about the size of a sesame seed, but it can reach the size of a small grape as it becomes engorged with your blood.”

New Hampshire is home to many other species of ticks, but the others don’t spread Lyme disease,” said Eaton. “In mid-October and November, the adult blacklegged tick—which used to be called the “deer tick”—is the one people are most likely to find.”

“The blacklegged tick itself becomes infected with Lyme disease-causing bacteria by feeding on an infected ‘reservoir host’, an organism that carries high levels of the bacteria in its bloodstream,” said Eaton. “In New Hampshire , the primary reservoir host for Lyme disease is the white-footed mouse.”

For more information about ticks and Lyme disease:

• N.H. Department of Health & Human Services' Web page on Lyme disease
• Extensive Web-based information on Lyme disease from the federal Centers for Disease Control
• Biology and Management of Ticks in New Hampshire
• Maine Medical Center Research Institute's Lyme disease research lab