Bad Weather Brings Mixed Prognosis for Tick-Borne Illnesses
By CHRIS BURRELL
When you're talking ticks and the many illnesses they can spread, bad weather can be a double-edged sword.
Donna Enos, the infection control nurse at the Martha's Vineyard Hospital, will tell you that the combination of rain and cool temperatures have kept many people indoors, significantly reducing their risk of a tick bite.
But Sam Telford, the parasitologist from Tufts University who has been studying ticks on both the Vineyard and Nantucket for the last ten years, says the weather could have the opposite effect when it comes to tularemia, the rare and potentially fatal disease that has infected 22 people on the Island in the last three years.
"When it's wet and cool, the organism could survive better," he told the Gazette yesterday in a telephone interview from his laboratory at Harvard University.
Tularemia is just one of the topics scheduled for a Martha's Vineyard Hospital forum this Thursday at 5:30 p.m. at the Oak Bluffs School library, a meeting devoted to discussion of preventing any of the tick-borne illnesses that thrive on the Cape and Islands, including Lyme Disease, babesiosis, ehrlichiosis and Rocky Mountain Spotted Fever.
Tularemia is the only disease of the bunch to have claimed a life, killing a Chilmark man back in 2000, the first summer of an outbreak that continued for the next two summers.
No new cases of tularemia have been confirmed this year, but Mr. Telford is convinced the disease hasn't left the Vineyard. "We will still find tularemia in ticks and animals out there," he said. "But whether we will see any human cases, we don't know."
The main point of Thursday's forum is focusing on prevention measures. "We want to bring everybody's awareness level up to where it should be," said Ms. Enos.
In the case of tularemia, wearing dust masks while mowing lawns or cutting brush could be the best barrier against the pneumonic form of the disease, which is contracted simply by breathing in contaminated air particles. Landscapers were found to be at the highest risk for the disease.
Of 22 cases, 18 of them have been landscapers or people who worked outdoors on a regular basis. All but five of the cases contracted on the Vineyard were the pneumonic form, a fact that has not only baffled scientists but also made the Island an absolute anomaly in the epidemiological record books.
No place else in the country has ever experienced such an outbreak. Epidemic intelligence teams from the federal Centers for Disease Control have flown to the Vineyard three times already, looking for clues to explain why pneumonic tularemia seems to have such a hold here.
While the disease is rare in any form - infecting only one or two people a year statewide - the pneumonic form is even rarer and more virulent than typical cases of tularemia, which are transmitted by a bite from a dog tick. Scientists investigating the outbreak have pinpointed potential hot spots for the disease around Katama and the Squibnocket area.
Mr. Telford said that Aquinnah, Chilmark and Chappaquiddick continue to be especially infested with ticks. But he also said that he expects to see the numbers of dog ticks decline this year since they have been on the increase since 1999.
But Mr. Telford, who continues to do field studies on the Vineyard in the spring and summer months, also said, "There hasn't been any real change in the transmission intensity of babesiosis and ehlichiosis in the last decade."
While public health officials have emphasized prevention efforts such as checking your body daily for the presence of ticks, Mr. Telford has been motivated by trying to unravel the mystery of tularemia on the Vineyard. Tularemia is also recognized by the federal government as a bacteria that could be used for bio-terrorism.
But the issue now is time and money. Officials at the CDC's division of vector-borne infectious diseases in Fort Collins, Colo. told the Gazette that they are not actively researching the Vineyard tularemia outbreak. And Mr. Telford is waiting on a grant from the National Institutes for Health.
"Until we get some more money, we can only do so much," he said. "I'm actually paying for this field study out of my pocket. I'm confident that some day the government will see it as important."
Panelists at Thursday's tick forum include Dr. Alan Hirshberg, director of emergency medicine at the Vineyard hospital; Susan Soliva, a researcher from the state department of public health, and Ms. Enos.