A new team of scientists, including one from the federal Centers for Disease Control and Prevention (CDC), has begun arriving on the Island to investigate what could be another outbreak of pneumonic tularemia, and they are calling on landscapers to help.

On Tuesday starting at 9 a.m. at the state forest headquarters, the scientists will offer free tularemia testing to all people who work in the landscaping field.

Katherine Feldman, an epidemic intelligence officer from the CDC who came to the Vineyard twice last year to investigate last summer's tularemia outbreak, said the testing will be confidential. Foreigners will not be asked questions about legal residency.

The CDC's arrival was prompted by last week's confirmation of the year's first case of pneumonic tularemia. Five other possible cases are being evaluated by state public health (DPH) officials.

Landscapers who show up Tuesday for the test will have a blood sample drawn and be asked to answer a short questionnaire.

Dr. Feldman will be joined by a scientist from the DPH and by Sam Telford, an expert in Lyme disease from Harvard University School of Public Health, who has also been studying tularemia on the Island.

"We're trying to see what's going with the current case and the suspect cases," said Dr. Feldman. "And we're talking to people here to better understand the ecology."

Tularemia is a rare disease, also known as rabbit fever since rabbits are the most prevalent carriers. The bacterial illness is most commonly transmitted from rodents to humans by way of a bite from the dog tick. But pneumonic tularemia is much more unusual, contracted by breathing in contaminated air particles.

Landscapers are at the highest risk for contracting this form of tularemia, according to scientists who suspect that bacteria are being kicked up in the air during brush-cutting and lawn mowing. What scientists don't know is the source of the bacteria - rodent feces, dead infected animals or possibly an increased rat population.

Last year, 11 of the 15 people who got sick with tularemia contracted the pneumonic form of the disease. Nationally, Martha's Vineyard is the only place in the country ever to experience an outbreak of pneumonic tularemia, not once but twice, and now possibly three times. An outbreak in 1978 also infected a total of 15 people.

So far this year, two cases of tularemia have been confirmed, one of them pneumonic. But the recurrence of just one case of pneumonic tularemia was enough to call back the CDC for the third time in a year.

Earlier this week, the state's top epidemiologist, Bela Matyas, called it "very unusual" that a case of pneumonic tularemia has come back this year. "Obviously there's some type of exposure that continues to pose a risk to people," he said. Of the five cases still under evaluation by the DPH, all involve people who work outdoors.