BOSTON — There are about twice as many animals testing positive for rabies this year compared to last year, according to public health officials.

Dr. Mike McGuill, the state’s public health veterinarian, said his lab has found 149 confirmed cases of rabies in animals already this year. There were 242 cases in all of 1997.

“We haven’t even entered the peak season yet,” he said.

In the summer months the Department of Public Health sees many more rabies cases because people are more likely to be outside and come into contact with the animals. The DPH is the only lab in the state that tests animals for rabies.

Last month a Pembroke boy was bitten by a rabid fox while playing in his back yard. Matthew Negus, 6, is now undergoing a three-week series of shots to keep him from contracting the illness.

Another Pembroke resident reported being attacked by a fox but was not bitten.

McGuill said the number of animals with the raccoon strain of rabies is going up mostly because of a recovery in the population of wild animals after they were ravaged by rabies in the early 1990s. Animals died in huge numbers between 1992 and 1995.

By 1996 the number of rabies cases in raccoons, foxes, coyotes, skunks and bats had plunged. But in the last two years the numbers have gone up again and it is those animals that are most often found infected with the disease.

“Those are the ones that are most likely to have encounters with each other because they are big enough to survive an attack by another animal and get rabies,” McGuill said.

The rabies cases are distributed equally throughout the state, except in Cape Cod and the islands where a vaccination program has succeeded in keeping the disease out of that area.

The State Department of Public Health and Tufts University have created a rabies barrier at the edge of the Cape by distributing bait that contains a rabies vaccine that raccoons in the area eat.