(HealthDay)—Transmission of tuberculosis from infected captive elephants to humans may be possible with long-term, close contact with the animals, according to research published in the Jan. 8 issue of the U.S. Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report.

In early 2013, an Asian bull elephant at a zoo in Multnomah County, Ore., tested positive for , and the disease was later found in two other bull elephants.

Officials also tested 96 people who had contact with the three elephants and found that seven of those who had extensive contact with the animals had . The three elephants were isolated and treated to prevent them from infecting other animals and people, and the seven affected people were offered treatment.

The findings show that captive elephants are a potential source of in people who have long-term, close contact with infected animals. Improved understanding of how the disease is transmitted between elephants and humans is needed to determine ways to reduce the risk of infection, the researchers said.

More information: Full Text

Journal information: Morbidity and Mortality Weekly Report