Death on Leathery Wings

For people who live in temperate countries, vampire bats are colorful items for horror stories. In Latin America they are a too real horror. They carry rabies and transmit it to humans and animals, whose blood they drink. Rabies does not necessarily kill the vampires, and anti-bat measures by humans do not kill enough of them. Last week a Brazilian naturalist, Dr. Augusto Ruschi, 41, was working out a new solution of the vampire problem: biological warfare with a disease that kills bats only.

The vampire menace of Latin America has been building up for several decades. Even before they carried rabies, the blood-drinking bats were not pleasant neighbors. When attacking sleeping humans, they generally go for the toes, sometimes creeping under the bedclothes like evil, winged mice. Sleeping animals are their staple diet. They generally bite on the wing, retreating and hovering in the air a few feet away to see if their victim has awakened. Dogs often wake up when bitten, but other animals generally do not. Several bats may flutter down to drink one trickle of blood.

Dynamite & Gas. Now that rabies is common among vampires, their bloodletting often brings agonizing death. In Trinidad 89 humans have died of bat rabies since 1935. Other countries also list human victims, but the principal damage is done to cattle. In the single Brazilian state of Rio Grande do Sul, vampires killed 50,000 cattle in 1956.

As bat rabies spread over Brazil, the government tried desperate countermeasures. It set up 15 centers to produce rabies vaccine, but immunity given by it wore off in a few months. Specially trained bat-killers attacked the bats' home caves with flamethrowers, dynamite and poison gas. They chopped down hollow trees where the bats shelter, but still bat rabies spread.

Naturalist Ruschi decided that the way to cope with rabid vampires was to learn everything possible about them. He had always liked vampires in a professional way ("Everybody calls me 'the bat man' "), and when bat rabies became a national problem, he turned his attention to it. He and his aides traveled thousands of miles through Brazil's back country; they studied 2,000 bat colonies, marked thousands of bats with dyes to learn their habits. They clocked the bats' flight (33 m.p.h.), and studied how bats find their victims by echolocation. Dr. Ruschi built a bat grotto at his museum to observe at close range their living, biting and eating habits. He determined that it takes 5,000 cattle to support an average colony of 50,000 vampire bats.

Let It Spread. In 1953, when Ruschi was bat-hunting in the back-country state of Mato Grosso, he found a cave piled three feet deep with dead and dying vampires. This looked promising, so he collected sample bats and hurried them to his laboratory. From them he isolated germs that will spread from bat to bat and kill them in 120 days. "The long incubation period is good," says Dr. Ruschi. "It helps the victim spread the disease before he dies."

Since 1953 Ruschi has been cautiously testing his germs. They kill bats all right, but he wants to be sure that they will not kill desirable animals or have other harmful biological effects. If no such disadvantages show up, the bat-killers of Brazil and other vampire-menaced countries will soon fan out into the jungle, catch vampire bats, infect them with the disease, and release them to return to their caves and pile them high with dead.

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