Deers can infect human beings with a rare kind of pulmonary tuberculosis, according to notes released from the field by the Center for Disease Control and Prevention (CDC) on Sep. 20.
The CDC said a case of pulmonary tuberculosis was reported to the Michigan Department of Health and Human Services in May 2017 in a 77-year-old hunter caused by Mycobacterium bovis (M. bovis).
The man had never visited countries with endemic tuberculosis, had not consumed unpasteurized milk, was not exposed to humans with tuberculosis, and resided in the northeastern Lower Peninsula of Michigan which has a low rate of human tuberculosis.
“The patient had regularly hunted and field-dressed deer in the area during the past 20 years,” said the CDC while explaining the cause of the rare TB in the hunter.
In 2002 and 2004, two human cases of deer-related infections caused by M. bovis were reported in Michigan and each resulted in the individuals needing medical treatment.
Tests were performed on infection samples obtained from the patient at the National Veterinary Services Laboratories in Ames, Iowa and the results were compared against an extensive M. bovis library, “including approximately 900 wildlife and cattle isolates obtained since 1993 and human isolates from the state health department.”
The CDC said the 77-year-old patient had acquired M. bovis in the course of his hunting activities, most likely while “field-dressing deer carcasses” and the infection became reactivated as pulmonary disease in 2017.
In Michigan, deers act as a reservoir host for M. bovis and authorities have suggested that while field-dressing deers, hunters in Michigan use personal protective equipment.
“In addition, hunters in Michigan who submit deer heads (for testing) that test positive for M. bovis might be at higher risk for infection, and targeted screening for tuberculosis could be performed. Close collaboration between human and animal health sectors is essential for containing this zoonotic infection,” said CDC.
Tuberculosis infection in humans can be caused by various strains. It can be a latent TB infection or it can be a TB disease. In the latent case, the TB bacteria can live inside a human body without causing disease.
“People with latent TB infection do not feel sick, do not have any symptoms, and cannot spread TB bacteria to others,” CDC said in another release.
“If TB bacteria become active in the body and multiply, the person will go from having latent TB infection to being sick with TB disease,” it said.
Millions in the United States have latent TB and health officials say they are at risk of infection if they do not seek treatment.
“If you think you may have latent TB infection, TB disease, or were exposed to someone with TB disease, contact your health care provider or your TB control office,” said the health officials.
Around 9,105 TB infections were reported in the United States in 2017, the lowest case count in U.S. history.