Fueled by a federal grant aimed at countering a bioterrorist attack, scientists at a Providence, R.I., pharmaceutical company are banking on the collection of blood samples from nearly two dozen Vineyarders to help them develop a new vaccine against tularemia, the rare disease with an unexplained presence on Martha's Vineyard.

Since the summer of 2000, 30 people on the Island have been infected with the disease. One of those cases was fatal.

The tularemia bacteria is also one of the top five bioterrorist agents listed by the National Institutes for Health (NIH). As part of a counter-terrorism initiative unveiled last summer by President George W. Bush, the NIH awarded EpiVax, Inc., a small biotechnology firm in Rhode Island, an $831,000 small business grant last fall to begin the first phase of creating a vaccine against the virulent disease.

Next Thursday at 5:30 p.m. in the Baylies Room at the Whaling Church in Edgartown, representatives from the company will come to the Vineyard and hold a tularemia forum and recruit people who have had the disease to participate in the research project that is expected to last two years.

What researchers really want is blood samples from as many as 20 such people.

"We'll take people who were exposed to tularemia in the past. Once you've been exposed to the pathogen, you generate a memory, and the next time you see it, the body fights it better and you don't get sick," Daniel Rivera, the laboratory director at EpiVax and a molecular biologist, told the Gazette yesterday in a telephone interview.

The blood sample needed is small, just eight to 10 tablespoons, said Mr. Rivera. Participants will be paid $100. Donna Enos, an infection control nurse at the Martha's Vineyard Hospital, has been hired by the company to draw the blood and screen participants.

The decision to turn to the Island for help was obvious. It's just a couple hours from Providence, a geographic advantage that gave EpiVax biologists the idea to apply for the grant. More importantly, however, the Vineyard is the only place in the country to experience two outbreaks of tularemia, one in 1978 and the other beginning in 2000. There were four confirmed cases on the Island last year.

Nearly all of the victims of the more recent outbreak have been people who worked outdoors, typically as landscapers. But what has made the Island even more notable in the medical history books is the fact that 21 of the 30 confirmed cases have been the pneumonic form of the disease, which is characterized by the sudden onset of flu-like symptoms.

Epidemiologists from the Centers for Disease Control (CDC) concluded more than three years ago that the pneumonic cases on the Island were likely caused by inhaling airborne particles laced with the tularemia bacteria. Landscapers were determined to be at the highest risk for contracting the disease, prompting a public health advisory that urged them to wear dust masks while mowing lawns and cutting brush. The disease is more commonly transmitted through a bite from a dog tick.

No one ever suspected that the Vineyard outbreak was the result of any terrorist attack, but the thread between bioterrorism and the pneumonic cases on the Island has drawn significant attention from the federal government. A terrorist attack would likely use airborne tularemia.

Three times in the last four and a half years, the CDC has dispatched epidemic intelligence teams to the Vineyard from its infectious disease facility in Fort Collins, Colo.

But the NIH move to push for a tularemia vaccine represents a significant shift in the federal approach. The epidemiologists from Fort Collins were collecting data here - rabbits, rats, ticks and soil samples - in an attempt to unlock the mystery behind the outbreak, answering the big question: Why is tularemia so prevalent on the Island and nowhere else?

In the wake of the Sept. 11 attacks and President Bush's anti-terrorism policies, the focus has turned simply to preventing transmission of the disease through a vaccine.

The grant to EpiVax is about developing counter measures to bioterrorism, said Lanling Zou, a program officer and molecular biologist with the NIH National Institute of Allergy and Infectious Disease in Bethesda, Md.

"Based on its potential for use as a biological weapon, tularemia is a category A priority along with anthrax and plague," she added.

Nationwide, there are just 200 confirmed cases per year of tularemia, Ms. Zou told the Gazette yesterday. An experimental vaccine is available, but only for scientists working in labs where they are exposed to the bacteria.

Mr. Rivera said the blood from Islanders who have had tularemia is a key component to developing a vaccine. Scientists at EpiVax, working in concert with biologists at Brown University and Rhode Island Hospital, will extract T-cells from the blood and use them to develop the building blocks for a vaccine.

"We expose them to these little synthetic peptides, and if they've seen tularemia before, they give a response, the cells will get turned on and secrete a protein immune response," said Mr. Rivera.

That's phase one. If successful, phase two involves testing the vaccine on mice at the University of Massachusetts Medical School in Worcester. Mice would be vaccinated and then infected with tularemia. They would also be infected first and then treated with the vaccine to see if it was therapeutic after exposure to the bacteria, Mr. Rivera explained.

For now, phase one depends on the Vineyard participating. This is where EpiVax is concentrating efforts.

Meanwhile, at least one scientist is still working to solve the riddle of tularemia on the Island. Sam Telford, an associate professor of infectious diseases at Tufts University, has continued to collect dog ticks from the Vineyard and study them for clues.

In November, Mr. Telford published a study in the Journal of Clinical Microbiology, detailing his field work on the Vineyard from 2001 to 2003. Findings show that of the 4,246 dog ticks dragged from Island fields and plucked from animals such as skunks, only seven-tenths of one per cent test positive for tularemia.

But in the Squibnocket region of Chilmark, that rate jumps to four per cent. What's more, skunks and raccoons trapped and released by Mr. Telford and his teams have also tested positive. "We collected six rabbits from our site near Squibnocket," he wrote in the journal. "Three of them were dead or dying and yielded evidence of infection by F. tularensis (scientific name for tularemia)."