Vineyard is the hot spot for tularemia

By Nelson Sigelman - May 24, 2007

Martha's Vineyard, well known as a popular summer resort, now boasts another, less welcome distinction.

The Island has one of the highest rates of pneumonic tularemia infection in the world. From 2000 through 2006, there were 59 cases associated with the Vineyard, more than in the previous 50 years. Of those, 38 were tularemia of the lung, according to state Department of Public Health (DPH) officials. There were nine cases diagnosed during that same time period elsewhere in Massachusetts.

With the approach of warm weather, public health officials Tuesday arranged a telephone press conference, attended only by The Times, to stress the risks of contracting the highly infectious and potentially fatal bacterial disease on the Vineyard.

"Every year at this time we try to raise awareness about the risk of tularemia," said Dr. Al DeMaria, DPH chief medical officer, "because we are still seeing cases and we want to do everything possible to prevent some of these cases."

Dr. DeMaria said cases begin to appear in May and tend to peak in June and run into July. "So, this is really the time of the year that we need to get the prevention message out there," he said.

The vast majority of people who have contracted tularemia, sometimes called rabbit fever, and those most at risk do outdoor work, such as landscaping, caretaking, and construction. However, the person who mows his or her lawn once a week or does outside yard work at home also faces the possibility of infection.

Dr. DeMaria said 82 percent of the cases occurred in people who had outdoor occupations. He said people who work outdoors should wear approved masks and tick repellant.

Tularemia occurs in animals and humans. It is caused by the bacteria Francisella tularensis and can be spread to people in a number of ways.

In addition to the pneumonic form, there are several types of tularemia infection. It can infect the eyes, skin, throat and bloodstream. "It is a very infectious organism," said Dr. DeMaria.

According to the Centers for Disease Control and Prevention (CDC), tularemia is endemic to Martha's Vineyard. The worst occurrence was in the summer of 2000, when there were 15 cases confirmed on the Island and one death, the first confirmed tularemia death in the state since 1996.

Dr. DeMaria said the one man who died postponed getting care, which may have contributed to the outcome.

Symptoms of a tularemia infection of the lung are similar to those of a bad case of flu. They may include fever and/or respiratory symptoms; chest congestion, tightness, or pain; lethargy; cough; or chills. A skin sore, swollen lymph glands, or a rash after a tick bite may also indicate an infection. Anyone with symptoms is advised to seek medical attention and let his or her doctor know that he or she has been involved in landscaping activities.

"I think the practitioners on the Vineyard have a very high index of suspicion," said Dr. DeMaria, "but people do not get sick going on the Vineyard. So they may leave the Island and develop their symptoms elsewhere and that has been an issue as well, because for somebody who has never thought about tularemia, that is not going to be the first diagnosis they come up with when somebody has a fever and an abnormal chest X-ray."

Local, state, and federal medical experts have been unable to provide any solid explanation for the outbreak of tularemia. The Vineyard experienced six confirmed cases of tularemia in the summer of 2006.

Based on past cases, the southern rim of the Island, in particular the Katama area of Edgartown and the Squibnocket area in Chilmark, appear to be the highest areas of risk.

Doctor DeMaria said one factor might be the suburbanization of the Vineyard environment, as more property changes from a wild environment to a landscaped environment.

Adding another clue to the puzzle, Dr. Bela Matyas, medical director of the DPH epidemiology program, said it appears that there are animals involved in the transmission that do not play as important a role elsewhere. In particular, skunks and raccoons show a high rate of infection and face no pressure from natural predators. Their droppings and carcasses could also play a role in the high rates.

A public health study conducted in 2000-2001 found that people on Martha's Vineyard with pneumonic tularemia most likely got sick by breathing in contaminated dust, soil, or grasses while brush cutting, lawn mowing, or doing other similar landscaping activities.

According to the Centers for Disease Control, people can get tularemia many different ways: by being bitten by an infected dog tick, deerfly, or other insect; by handling infected animal carcasses; by eating or drinking contaminated food or water; or by breathing in the bacteria.

Dr. DeMaria said that tularemia also occurs with some frequency in fours states in the southwest portion of the U.S., but is nowhere as focused as it is on Martha's Vineyard. The other distinction is that the pattern of illness is very different. Most of those forms are the skin form of tularemia.

Dr. Matyas said Martha's Vineyard is probably the only place in the world with such a high rate of pneumonic tularemia infection. He said that in Sweden and other places in Europe there are similar large outbreaks of pneumonic tularemia, but it is with a less virulent type of tularemia that carries a lower risk of fatality.

Tularemia, in aerosol form, is considered a possible bioterrorist agent. That risk has spurred research efforts.

Epivax, a Rhode Island based biotechnology company, has received a grant from the National Institutes of Health to develop a tularemia vaccine. Epivax selected Martha's Vineyard as a research site because it is one of the few places where the air-borne form of the disease has been seen with any frequency.

For more information, contact the Department of Public Health toll free at 1-888-658-2850 or go to the DPH web site at www.mass.gov/dph.