A new report from the U.S. Centers for Disease Control and Prevention appears to show that humans can contract a rare type of tuberculosis, called bovine tuberculosis, from deer. The report details the case of a Michigan hunter that apparently contracted the illness after contact with an infected deer. It’s the second report concerning disease-carrying animals the CDC has released this month.
In the case detailed in the new report, a 77-year-old Michigan man was diagnosed with a case of tuberculosis in 2017. The man had been a hunter for two decades and lived in the northeastern Lower Peninsula of Michigan, which has low numbers of human tuberculosis diagnoses, but many deer test positive. The unnamed patient had hunted deer in the same area where two other hunters were infected more than 15 years earlier.
The average person’s risk of bovine tuberculosis is low as the disease is quite rare, accounting for less than 2 percent of total tuberculosis cases in the U.S. It’s present in wild bison, elk, and deer, but has mostly been eliminated from commercial cattle. Human infections typically occur from eating or drinking unpasteurized dairy products, but can also be transmitted through direct contact with an open wound.
In the case of the unnamed hunter, there was no known exposure to anyone with tuberculosis and he did not drink unpasteurized milk. The CDC believes he became infected after inhaling the pathogens while removing a dead deer’s infected organs. CDC officials recommend that hunters wear protective gear when field-dressing animals.
The symptoms of bovine tuberculosis are pretty similar to other strains of tuberculosis that infect humans. Infected individuals will experience a severe cough, fever, weight loss, and chest pain. Bovine tuberculosis is resistant to the antibiotic pyrazinamide, one of the drugs generally used to treat tuberculosis, so other treatment methods are needed. Anyone who works in close proximity to carrier animals or consumes raw dairy products should be regularly screened for the illness. If a deer head submitted for tuberculosis tests positive, hunters should also be screened.