The Centers for Disease Control (CDC) is warning hunters ahead of the upcoming deer season to be aware of a strain of tuberculosis that can be passed from game animals to humans.
The CDC believes an unidentified 77-year-old Michigan man contracted pulmonary tuberculosis after being exposed to the Mycobacterium bovis bacteria. The man had no history of travel to countries with endemic tuberculosis, no known exposure to persons with tuberculosis, and no history of consumption of unpasteurized milk, all common causes of TB in the United States.
He did, however, live in an area of Michigan with a higher-than-usual concentration of M. bovis-infected deer, and he regularly hunted and field-dressed game animals in the area over the last 20 years.
The CDC believes he likely inhaled the bacteria while cleaning one of his kills.
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Humans rarely contract TB from deer, according to the Indiana Division of Fish and Wildlife, but the CDC noted two previous cases in Michigan in 2002 and 2004. In both cases, the patients exhibited signs of an active disease and required medical treatment.
To avoid infection, the CDC encourages hunters to wear “personal protective equipment” while field dressing an animal. The study does not specify the kind of equipment that should be used, but many hunters use face masks and latex gloves during the cleaning process.
Like the more common type of Tuberculosis bacteria, Mycobacterium tuberculosis, M. bovis can lead to active infections or remain dormant in a person’s body for years. The disease can be reactivated if a person becomes immunocompromised, according to the CDC. The Michigan man described above may have contracted the bacteria long before exhibiting signs of infection.
The CDC also encourages “close collaboration between human and animal health sectors” to stop the spread of the disease. The study points out that hunters who submit deer heads that test positive for M. bovis might be at higher risk for infection, and health officials could target those individuals for health screenings.
Tuberculosis isn’t a common disease in the United States among humans, but it can be treated with antibiotics. While it can be fatal in some cases, most people who contract it can recover with a months-long regiment of antibiotics, William Schaffner, MD, told Health.
The disease is also uncommon among deer populations. The CDC notes that only 0.05% of the deer heads tested in Michigan were infected, and the Indiana DFW describes it as a “very rare disease.”
Infected deer appear emaciated and often have a cough, nasal discharge, and difficulty breathing. Small lesions or abscesses may be visible inside the chest cavity, covering the lungs, liver, and ribcage in late developed individuals, according to the Indiana DFW.