The United States is currently in the midst of an elephant tuberculosis epidemic. There have been more than 60 confirmed cases of tuberculosis in US elephants—in a population of only 446. In June, a third elephant was diagnosed with tuberculosis in the Oregon Zoo, and this past November an infected elephant died in a California refuge.

The disease poses risks not just for the large land mammals but also for us. While most infectious diseases are not easily passed between species, tuberculosis is an exception. The bacteria can be transmitted by close contact or by droplets containing bacteria that float through the air after a sneeze or cough. Our current animal practices are driving the present epidemic.

In 2000, at the Los Angeles Zoo, 55 keepers tested positive, their bacteria a genetic match to the infected animal they handled—strongly implying, but not proving, that the keepers had acquired the infection from an elephant.