Just before entering veterinary school, Michelle found a summer job at a wildlife refuge. She spent most of her time caring for Asian and African elephants until she came down with what she thought was the flu.
Chest x-rays showed white spots on Michelle’s lungs. Additional tests of Michelle’s sputum confirmed she had active TB, or TB disease.
According to a new NIOSH blog, studies have shown that about 12% of Asian elephants and 2% of African elephants in captivity are infected with tuberculosis (TB), which is caused by a germ called Mycobacterium tuberculosis. Studies have also documented the transmission of the bacteria from elephants to humans working in close proximity to the animals.
Indeed, an elephant who had arrived at the refuge from an exotic animal farm and was staying in the quarantine barn, tested positive for TB. In Michelle’s case, she may have become infected from direct transmission when working with the elephants or through indirect transmission of the TB bacteria, which could have become airborne during routine barn maintenance such as sweeping waste or pressure washing.
The practice of pressure washing might also have created a contaminated mist that could have lingered in an enclosed barn for hours. Although workers typically wore respirators when working inside the barn, air could have flowed between the barn and the adjacent office where employees did not wear respirators.
Other workers who were in contact with the TB-infected elephant were given the tuberculin skin test and three also tested positive. These other workers, who did not have symptoms, were infected with the TB bacteria but were not sick—known as a latent infection. Partly because of Michelle’s diabetes, her immune system was not able to fight the bacteria; the TB bacteria became active, multiplied, and caused TB disease.
Among the various practices and policies recommended by NIOSH to help reduce workers’ exposure to TB at a wildlife refuge, zoo, or circus that houses elephants include wearing respiratory protection (N95 filtering facepiece respirator or greater) when working within 25 feet of an elephant with known or suspected TB disease or within the elephant stall area, regardless of whether the ventilation systems are functioning or elephants are present. It is important to note that the 25-foot distance is recommended in the absence of other data; no evidence is available to define a safe distance from a TB-infected elephant.
Protection greater than an N95 filtering facepiece respirator (e.g., a full facepiece elastomeric respirator or powered air purifying respirator [PAPR]) should be considered for aerosol-generating procedures such as high-pressure washing in the barn. Ensure that respirator use is in conformance with the OSHA respiratory protection standard.
Read more about a NIOSH Health Hazard Evaluation conducted at an elephant refuge and the specific recommendations made for that facility.