Science: Beware of Bats

In the long memory of man, the fly-by-night, leather-winged bat has seldom been anything but a creature of ill repute—a companion of witches and devils and a portent of disaster. Though naturalists like to argue that bats are humanity’s benefactors because they gobble vast quantities of insects, rare is the man who even bothers to listen. Soon, even the naturalists may moderate their enthusiasm, for the U.S. Public Health Service has produced scientific backing for the bat’s repulsive reputation.

Public Health scientists got interested back in 1953 after a Florida boy was bitten by a bat that was found to be infected with rabies. The boy survived, but investigation showed that other apparently healthy bats were rabid too. At first, the danger from rabid bats seemed small because bat bites are a rare problem among humans. Then in 1956 a Texan who had been banding bats went partially blind, had convulsive seizures when he tried to drink water, and soon died. Rabies virus was found in his brain. In 1959 a California mining engineer who had been searching caves in Mexico and Texas for deposits of bat guano got sick and died after suffering nausea, hydrophobia, foaming at the mouth and extreme anxiety—the characteristic symptoms of rabies. Both men were sure that no bat had bitten them.

Repulsive Carpet. Alarmed by this evidence that bats can transmit rabies without biting, the Public Health Service assigned Dr. Denny Constantine, 36, a lifelong student of bats, and a crew of hardy assistants to the ugly and dangerous job of checking further. Researcher Constantine is not easily daunted. During field work in Alaska six years ago, he crawled into a den of hibernating bears and took the rectal temperature of the biggest one while pacifying the restive animal with lumps of sugar. But for his new job he needed more equanimity than ever. Bat caves are chambers of horror. Their floors are deep in stinking guano and littered with the skulls and bones of long-dead bats. Over this repulsive carpet crawl fierce, flesh-eating dermestid beetles and their larvae—so numerous that the floor seems alive. When a sick or senile bat falls from the ceiling, the beetles crowd to devour it. The walls are thick with mites, ticks and other bat parasites. The air of the cave is foul with the unpleasant ammoniacal odor of bats, whose excreta comes showering down.

In the summer of 1960, Dr. Constantine and his crew moved into one of these noisome spots, the Frio Cave in southern Texas. While rabid bats flew overhead spraying them with urine, they slogged into the cave carrying wire-mesh cages containing dogs, domestic cats, raccoons, ringtail cats (a raccoon-like animal of the Southwest), coyotes, grey foxes and one striped skunk. The animals were fed and tended carefully for one week, then removed and isolated. One fox, two coyotes and one ringtail cat died of rabies.

Sprinkled Tourists. The evidence was not yet conclusive, but at the Carlsbad Caverns in New Mexico where bats are a principal tourist attraction, Rangers were persuaded to keep spectators clear of the bats’ flyways. Bats begin to urinate almost as soon as they become airborne, and for years the Carlsbad bats have sprinkled tourists with urine that may well have been infected.

After the first safety precautions, more careful tests were needed. This summer Dr. Constantine and his crew moved coyotes, grey foxes, silver foxes, striped skunks, spotted skunks, raccoons, dogs, cats, ringtail cats and opossums into Lava Cave in New Mexico. Some of the animals were in simple wire cages, exposed to bats, their excreta and their parasites. Other test animals were protected, some of them guarded against everything but the foul air of the cave. They were brought out again after a month. Thus far all ten coyotes and all ten foxes have died after exhibiting the dreadful symptoms of rabies, and the rabies virus has been found in their brains. Even the noxious air of a bat cave seems to transmit the disease. And scientists have begun to theorize that bats may be the ultimate source of unexplained outbreaks of rabies that appear among wild animals and may spread to domestic animals and to man. Dr. Constantine is particularly worried about cave-visiting tourists and other spelunkers. Says he: “It seems evident that an emphatic warning for persons to avoid densely populated bat caves is indicated at this time.”