THURSDAY, Dec. 14 (HealthScout) -- For the first time in two years, people in the United States have died from rabies, the Centers for Disease Control and Prevention (CDC) reports today.

This fall, five people around the United States died of human rabies. Four of the five cases were probably caused by bats, officials say. In the four cases, the patients reported contact with bats, but most of the patients weren't sure if they had been bitten or scratched by the animals. The fifth case was the result of a puppy bite in Ghana before the man traveled to the United States. The deaths are reported in the CDC's latest Morbidity and Mortality Weekly Report.

"The reports have been coming in all fall," says Dr. Robert Gibbons, an epidemic intelligence service officer with the CDC in Atlanta. "And if you look back over the '90s, this is sort of in the normal range when you look at a whole year. We had six cases, for example, in 1994."

This year's five deaths occurred in California, New York, Georgia, Minnesota and Wisconsin. The patients were originally diagnosed as having either heart attacks, limb numbness, carpal tunnel syndrome and bowel obstruction. Spiking fevers were quickly followed by lung and kidney failure and delirium.

In one case, the patient had been renting a room on the upper floor of an old house. He reported bats in his living quarters that had landed on him while he slept. A later investigation of the house revealed a colony of close to 200 Mexican free-tailed bats in the attic.

As many as 18,000 Americans get rabies shots each year because they have been in contact with animals that may be rabid, according to the National Institutes of Health. In December 1998, according to the CDC, only one person died of rabies in the United States that year. The World Health Organization (WHO) estimates that around the world more than 40,000 people die every year from rabies. WHO also estimates that 10 million people worldwide are treated after being exposed to animals that may have rabies.

Gibbons says most rabies cases happen in the autumn. "We don't quite know why, but since the majority of the cases are due to bats, it could be something to do with the bats migrating or seeking winter roosts," he says. "But that is pure speculation."

Rabies is one of the oldest and most deadly infections of the central nervous system known to man. Caused by a virus in the saliva of infected animals, it is usually transmitted by bites from infected animals. Only in rare cases is the disease transmitted when saliva comes into contact with a scratch or broken skin, but the virus can also be spread in the air, according to the National Institutes of Health.

But it could be animals other than bats that are the source, says Barbara French, conservation information specialist for Bat Conservation International in Austin, Texas. "What happens in a number of bat cases is that the person is so sick by the time they are treated that they cannot give medical officials a really complete exposure history," she explains. "They can use a test to tell what the original host may have been, but they can't tell if there was an intermediate host."

"A cat can be an intermediate host, for example," French says. "Cats tend to like to catch bats, and that's why it's important to keep your cats vaccinated." French says bat rabies is one of the most rare causes of mortality in the United States. "In fact there are over 40,000 cases of rabies around the world each year and in 99 percent of the cases, the disease is due to dog rabies."

What To Do

"The take-home message is that if you have a bat touch you in any way, seek medical attention to see if you need a rabies vaccination," Gibson says. "And the message for the doctors is that you need to consider rabies whenever you have a patient with progressive encephalitis, a brain infection."

The CDC says that anyone who is bitten or scratched by an animal should wash the wound thoroughly and go to a doctor immediately. And should you have contact with a bat, the bat should be collected if at all possible and tested for rabies.

For more information, visit the National Institute of Allergies and Infectious Diseases. And to learn what you can do about a bat infestation, check out the Bat Conservation International.

And you can read these other HealthScout stories on rabies.