When I was in Brazil, years ago, I hiked into a remote farm and spotted a sad looking horse standing in the field with blood stains streaming down its neck. When I asked the farmer what had happened to the horse, he said it was vampire bats. Made me involuntarily shudder and look up. Of course there were no bats zeroing in on my neck at the moment because it was broad daylight.
Vampire bats hunt by night. Typically, they will land on or near their prey without disturbing its sleep, then creep to a position that will give them good access to blood flow. With razor-sharp teeth, they slit the skin of their victim and then lap up the blood as it oozes out. In most instances, the raid is so gentle that the victim never is aware of the attack until the next morning when the blood is apparent.
The biggest problem isn't the loss of blood — it's disease. Bats are carriers of rabies, and they can transfer the disease to their victims through the open wounds left by the bites.
Up until now, in the U.S., vampire bats have been nothing more than mysterious characters in horror stories. But the recent death of a Mexican teenager who had migrated to Louisiana to work on a sugar cane plantation has brought a focus on the issue of vampire bats and rabies invading the U.S. And the speed of the young man's death raised eyebrows at the Centers for Disease Control (CDC).
According to a CDC report, the victim suffered an especially virulent form of the rabies virus. Normally, the incubation period for rabies is about 85 days, but in this case it was only 15 days. The symptoms progressed from fatigue to shoulder pain, to a drooping left eye, to numbness in the left hand. He developed a respiratory distress and a fever that climbed to 101.1 degrees F. A postmortem test of the victim's brain tissue confirmed a vampire bat variant of rabies.
Of great concern to the CDC is the feared expansion of the vampire bat habitat. The bats are common in parts of Brazil, Chile, Argentina and Mexico, but now appear to be expanding toward the United States. According to a CDC spokesman, "Expansion of vampire bats into the United States likely would lead to increased bat exposures to both humans and animals, and substantially alter rabies virus dynamics and ecology in the southern United States."
A bat attack on a human is not the only way for the rabies to spread. If the bat attacks a dog or cat, or some other domesticated pet or livestock, the rabies virus can eventually be transferred to humans through interaction with the affected animals.
If you think you might have come into contact with a rabid animal, contact your doctor as soon as possible. The symptoms listed above that the Mexican fellow suffered are typical.