6. A 32-year-old farmer consults with symptoms of night sweats, low-grade fever, cough, and fatigue. He does not smoke. He has a history of asthma. The chest x-ray required for immigration was normal 5 mo ago. He received the BCG vaccine as a child. The skin test for tuberculosis is positive at 15 mm. The most likely diagnosis is
D) Mycobacterium bovis
E) M. tuberculosis
Correct Answer D. Mycobacterium bovis
Most people are at very low risk for being infected with M. bovis. People at higher risk include individuals who work with cattle, bison, or cervids (e.g., deer or elk), or products from these animals such as hides, milk, or meat. Examples of occupations or hobbies that might put people at increased risk include ranching, dairy farming, working in a slaughterhouse or as a butcher, and hunting.
Not all M. bovis infections progress to TB disease, so there might be no symptoms at all. In people, symptoms of TB disease caused by M. bovis are similar to the symptoms of TB caused by M. tuberculosis; this can include fever, night sweats, and weight loss. Other symptoms might occur depending on the part of the body affected by the disease.
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