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Rabbit 'Dust' Leads to Brush With Fever

Feces in yards likely caused malady on Martha's Vineyard

THURSDAY, May 3 (HealthScout) -- Mowing the lawn isn't normally a very hazardous activity, but cutting grass and brush may have been behind last summer's mysterious East Coast island outbreak of "rabbit fever" that killed one person and sickened 14 others.

However, why the disease, officially known as tularemia, popped up on Massachusetts' Martha's Vineyard is not clear, says Dr. Katherine Feldman, who studies epidemics for the Centers for Disease Control and Prevention (CDC).

She announced her findings at the recent conference of the Epidemic Intelligence Service.

Only 100 to 200 cases of tularemia -- named after Central California's Tulare County -- are reported each year in the United States, Feldman says.

Usually, humans get the disease through dog tick bites. But at least 11 of the 15 tularemia victims on Martha's Vineyard got another airborne strain of the disease, apparently from the urine and feces of infected rabbits and other small animals.

In addition to causing enlarged lymph nodes, fever and lethargy, the second strain attacks the lungs and can cause pneumonia. However, it can be treated fairly well with antibiotics, Feldman says.

Federal medical investigators went to Martha's Vineyard twice last year to compare the victims to groups of uninfected residents. Those who got sick were more likely to have used a lawnmower or brush-cutter in the weeks before becoming ill, Feldman says. Eight of the 11 victims of airborne tularemia had done this yard work in the two weeks before they got sick.

Some were homeowners working in their yards, while others were professional landscapers. One victim accidentally ran over a rabbit with a lawnmower.

Investigators also tested animals on the island and found two, a rat and a vole (a mammal similar to a mouse), that appeared to have the tularemia bacteria.

Feldman suspects that the victims breathed in dust that carried the bacteria. But she says she doesn't know why the summer of 2001 was so tularemia-friendly on Martha's Vineyard.

"There are a lot of pieces that we haven't figured out yet. We don't know if the temperature has to be at a certain level or if we need a certain amount of rain," she says.

Tularemia was common in Massachusetts in the mid-1930s, after thousands of rabbits were imported to New England to be hunted, says Dr. Alfred DeMaria, a state public health officer.

But he says the rabbit population apparently wasn't higher than usual and doesn't seem to explain last year's outbreak, he says.

What To Do

Tularemia can infect people just about anywhere, especially in the South and Central states. It is most common during the summer, when people go hiking and get bitten by ticks, and in November and December during hunting season.

If you're mowing your lawn, check first to make sure no dead animals are around. Keep your gardening equipment well maintained and seek medical attention if you come down with a fever within two weeks after moving or cutting brush. And consider wearing a mask.

Read more about tularemia at the Hawaii Department of Health. has tips on what to do if you get bitten by a tick.

Or, read previous HealthScout articles on ticks and rabbit fever.

SOURCES: Interviews with Katherine Feldman, D.V.M., MPH, epidemic intelligence service officer, CDC, Ft. Collins, Colo.; Alfred DeMaria, M.D., director of communicable disease control department, Massachusetts Department of Public Health, Boston
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