They are considered the most noble creature to grace Earth. They have massive brains, complex forms of communication, the ingenuity for tool use, and the capacity to express emotions, including grief and empathy. Yet, as impressive as they are in size and majesty, elephants can still be felled by the most human of ailments: tuberculosis.Tuberculosis is an infection that has been infecting humans for millennia, but it is also a promiscuous organism that can infect the lungs of many other mammals. The ability of humans to transmit this infection to domesticated animals with a hearty sneeze or cough that sprays droplets harboring the bug has been known since the 19th century. It is an infection that has “let its roots into all animal species,” both wild and domestic (1).We have been aware of the ability of tuberculosis to infect elephants for millennia: a 2,000-year old Sanskrit treatise on veterinary medicine, the Hastăyurvĕda, makes mention of a pulmonary infection among these pachyderms similar to tuberculosis (TB)(2). A pandemic of the bug has also been tentatively implicated in the extinction of the elephants distant relative, the mastodon (Mammut americanum) as lesions characteristic of TB have been found in the ribs and the tarsal bones of the feet of mastodon specimens (2).There are currently 446 captive elephants in North America distributed among zoos, circuses, private owners, and animal sanctuaries (3). Over 60 cases among various herds have been diagnosed and confirmed with a TB infection since 1983, when an American circus elephant fell ill (4). Since then, isolated outbreaks among elephants and their human handlers have materialized throughout the United States in an ongoing, low-intensity, nationwide epidemic of elephantine tuberculosis.
Diagnosing the infection in elephants is difficult. For starters, many tubercular elephants are asymptomatic, and in those that do express signs, symptoms tend to be vague: weight loss, exercise intolerance, coughing, and respiratory secretions. Furthermore, diagnosis of TB in an elephant is a challenge, requiring a bacterial culture of what is called a “trunk washing,” in which the trunk is flushed with saline and the fluid and mucus are discharged into a heavy duty one-gallon plastic bag once a day for three days
