Shortly after an emaciated captive elephant named Hattie performed with Circus Vargas, in Southern California, she died in a trailer going to an exotic animal farm in Illinois. Her cause of death, on August 6, 1996, was tuberculosis. Testing revealed that another elephant in Hattie’s circus group also was infected.

In the mid-1990s, after the deaths of several high-profile captive elephants in the United States, veterinarians became aware that the animals had the human strain of tuberculosis (TB). Since then, more than 60 captive elephants—some of which have since died—have been confirmed with the disease, says Susan Mikota, co-founder of Elephant Care International, a U.S.-based nonprofit that provides elephant health-care support. Last year, one elephant was diagnosed with TB at