More deer ticks infected with disease-causing pathogens in 2008

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East Bay rate especially high, according to URI tick expert

KINGSTON, R.I. – January 21, 2009 – If we haven’t already heard enough about what was bad during 2008, here is just a little more troubling news—deer ticks in Rhode Island were more likely than normal to be infected with pathogens, like the one that causes Lyme disease. In some places, ticks were nearly twice as likely to be infected.

After being briefed by University of Rhode Island tick experts, Congressman Patrick J. Kennedy is calling for state officials, and especially East Bay residents, to take special note of new findings about Lyme disease risk in Rhode Island.

Tick surveillance and testing in 2008 showed that the infection rate of Lyme disease-causing bacteria, called spirochetes, was nearly twice as high in deer ticks collected from sites in Middletown and Jamestown than elsewhere in the state. These surprising results follow on disturbing surveillance findings in 2007 that showed the abundance of nymphal deer ticks had jumped more than 200 percent at several forested locations on Jamestown and Aquidneck Islands.

The newest findings further amplify concerns of public health officials about residents facing significant increases in Lyme disease risk.

“Although summer is months away, these new findings are alarming and should serve as a strong reminder to residents near these sites, as well as all Rhode Islanders, that they need to be vigilant in educating themselves about the risks posed by ticks and Lyme disease. I commend the researchers at the University of Rhode Island for working to disseminate this information and the essential strategies to help protect people from Lyme disease,” said Congressman Kennedy.

According to URI Entomology Professor Thomas Mather, director of the Center for Vector-Borne Disease, one in five nymphal deer ticks (20 percent) typically carry the Lyme disease bacteria, while as many as one in two adult ticks are typically infected. But in 2008, infection rates for nymphal deer ticks in Middletown and Jamestown were 48 percent and 42 percent, respectively, while rates in South Kingstown, West Greenwich and Foster were more normal, ranging between 20 percent and 28 percent.

“The high Lyme infection rate in ticks from East Bay sites is very troubling,” said Mather. “If the trend continues, we may see an unprecedented up-turn in disease cases from that portion of the state if no action is taken.”Infection rates for babesia and anaplasma, diseases also transmitted by deer ticks, were slightly higher than normal in South County and other West Bay sites tested, but in ticks from East Bay sites, rates for these two infections were the lowest in the state. In 2008, about one in ten ticks was infected with multiple agents.

“Pathogen infection rates in ticks usually vary throughout Rhode Island by a few percent,” said Mather, “but rodent populations have been through the roof over the past few years, especially white-footed mice, and they are the main animal hosts involved in infecting deer ticks with pathogens that infect humans.”

Deer tick abundance in Rhode Island during the spring and summer of 2008 was 24 percent lower than in 2007, though counts were notably higher in Johnston and Coventry.

To learn how to protect yourself and your family from tick bites and disease, go to

Percentage of nymphal deer ticks carrying

Town, Lyme disease, babesiosis, anaplasmosis

Foster, 20, 28, 14

West Greenwich, 26, 34, 10

Jamestown, 42, 16, 4

Middletown, 48, 2, 0

South Kingstown (a), 26, 10, 14

South Kingstown (b), 28, 14, 8