Just two years after it was first identified as a disease in the U.S., AIDS was running rampant through gay populations and drug users, and many Americans feared it could be spread through routine contact. TIME’s cover story zeroed in on the scientists from the Centers for Disease Control who were tracking AIDS to ensure that it wouldn’t lead to a nationwide epidemic.
Asking questions. Hunting for clues. Testing theories. Hitting blind alleys. Asking more questions. The assault on the mystery of AIDS is a prime example of how disease detection works. The foundation has been laid by epidemiologists who have carefully analyzed the spread of the disease. So far, 75.9% of the victims in the U.S. have been active homosexual men, 16% intravenous drug users, 5% immigrants from Haiti, and 1% hemophiliacs. Only 96 victims so far are not known to be members of one of these risk groups.