A bat's bite, unfelt, could bring rabies

Virginia man died from bite last year, but never felt it happen

Once ill, disease is always fatal

June 17, 1999|By Denise Grady | Denise Grady,New York Times News Service

Last Dec. 15, when a 29-year-old inmate at the Nottoway Correctional Center in Virginia became ill with muscle pains, vomiting and abdominal cramps, he was simply given an aspirin substitute. But over the next few days his symptoms worsened: Pain and tremors developed in his right arm, and he began to have trouble walking.

Three days after visiting the prison clinic, he was taken to a hospital in Richmond, with a fever of 103 degrees. Within hours, he began to hallucinate, and he became agitated and disoriented. He also started to salivate copiously.

After three days, a doctor began to suspect the worst and took a bit of skin from the nape of the man's neck for a biopsy.

The next day, Dec. 22, the diagnosis was confirmed: The man had rabies. The biopsy detected it because he was at a late stage in the illness, when the rabies virus had already advanced into the brain and followed nerve fibers back out again, into the salivary glands, cornea and neck.

Too late

It was too late to save him. Although a vaccine can prevent the disease in someone who has been bitten by a rabid animal, it works only if given before symptoms begin. Once a person becomes ill, the disease is almost always fatal.

The Virginia man died on Dec. 31, becoming the only person in the nation known to have died of rabies last year. As a precaution, 48 people who might have come in contact with his saliva while he was ill were given shots of immune globulin and five injections of rabies vaccine, at a cost of about $1,000 per patient. Such prophylactic treatment is routinely given to people who might have been infected by a rabies patient, even though virtually every case is caused by an animal bite and there has never been a documented case of human-to-human transmission in this country.

An especially disturbing aspect of the case was that no one knew how the prisoner had contracted the disease. Even more unnerving, that mysterious pattern is typical of rabies deaths in the United States in the past 20 years. A person gets sick, and rabies is not even suspected until late in the disease or after death. The victim must have been bitten or scratched by a rabid animal -- almost invariably a bat -- but nobody, not even the patient, knows how or when.

30,000 people a year

Worldwide, 30,000 people a year die from rabies, mostly in developing countries where dogs are not vaccinated and treatment is not available for bitten people. Prophylactic treatment is recommended for travelers to those countries. In this country, vaccination of pets and preventive treatment in people bitten by animals have made rabies extremely rare in humans, with no more than a case or two a year.

Nonetheless, rabies still has a unique power to terrify. It conjures up images of mad animals foaming at the mouth and of people dying horribly in the throes of hydrophobia, tormented by thirst but prevented by throat spasms from taking a drink. Recently, the parents of a child bitten by an otter at a Florida zoo decided she should have prophylactic treatment, even though none of the otters appeared sick.

The only thing more frightening than the thought of being attacked by a rabid animal, perhaps, is the notion that a person can be bitten by an infected bat and not know it.

The strain of rabies virus that killed the man in Virginia was one found in either of two mouse-size, insect-eating bats that live all over the United States: the silver-haired bat or the eastern pipistrelle bat. But when epidemiologists checked medical records and questioned prison employees and the man's family and friends, they found no evidence that he had been bitten or scratched by a bat or any other animal.

There were no signs of bats inside the prison. Inmates said they saw bats outside just occasionally, during summer.

"An unrecognized bat bite" was the only explanation epidemiologists could offer, they wrote in an article last month in Morbidity and Mortality Weekly Report, a publication from the Centers for Disease Control and Prevention. They could not even pinpoint when the man might have been bitten, because the incubation period for rabies can range from weeks to months or, occasionally, even a year. Symptoms may come on fastest when the bite is close to the head, because then the virus has a shorter trip up nerve fibers to the brain.

Of the 25 cases since 1981 in which people contracted rabies in this country, 22 involved strains that could have come only from bats, and 16 had the silver-haired bat strain found in the Virginia man. Everyone in those cases died, including several children. But only one patient was aware of having been bitten. In the rest, the exposure was described as "unknown," though in many cases family members or patients themselves recalled that a bat had got into the house or workplace.

But that means one can be bitten by a bat without knowing it, something most people would find hard to imagine.

It can happen

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