Patient 1, 2002

In January 2002, a 74-year-old man sought medical care, reporting malaise, anorexia, and fever. Past medical history included ischemic bowel disease, vascular disease, partial gastrectomy for peptic ulcers, and left upper lobectomy for squamous cell carcinoma (December 1999). On February 1, he was hospitalized with persistent fever and nonproductive cough; results of a chest radiograph were consistent with necrotizing pneumonia. A tuberculosis (TB) skin test (TST) result was negative, and a sputum smear was negative for acid-fast baccilli (AFB). After 5 days, the patient had not improved clinically; chest radiograph showed increasing infiltrate on the left side. Diagnostic bronchoscopy was performed, which yielded an AFB-positive smear. The condition of the patient deteriorated clinically over the next 10 days; he died on day 16 of his hospitalization.

Laboratory confirmation for TB, speciation, and antimicrobial drug susceptibility testing were pending at the time of his death. Genotyping analysis showed that the M. bovis isolated from this patient matched the circulating deer/cattle strain (Table 2).

In his youth, patient 1 lived on a farm geographically distant from the current bovine TB–endemic area. His first wife had a reported diagnosis of TB after their divorce >40 years before, and his second wife reports he drank unpasteurized milk as a youth. He moved to the edge of Deer Management Unit (DMU) 452 in 1994, which is the focal area for the bovine TB outbreak in deer. There, he ran a business with a buck pole where hunters displayed killed deer. Additional potential exposures included hunting white-tailed deer and consuming venison (>10 years before his death), handling a deer carcass from the DMU 452 vicinity in 2000, and recreational feeding of deer.

This patient was in poor health at the time of death, having acute and chronic illness. His poor health would have rendered him more susceptible to infection with M. bovis and would have made the progression from latent infection to clinical disease more likely. The pathology results from his lung resection in December 1999 provided no evidence of TB; therefore, infection was likely acquired subsequently. The genotyping results from patient 1 matched those of the circulating deer/cattle strain, which suggested exposure to infected cattle or deer. The lack of recent exposure to cattle suggests that deer are the more likely source of infection.

Patient 2, 2004

Patient 2 was a 29-year-old, previously healthy man. On October 1, 2004, he shot a white-tailed deer just outside DMU 452. While field dressing the animal, he punctured his left index finger with a hunting knife. Approximately 18 days after the injury, his finger became inflamed and painful, so he sought medical treatment. Based on his history of exposure to a deer with lesions, a TST was administered; the result was negative. After ≈10 days of antimicrobial drug therapy, the wound had not improved. He was hospitalized, and the infected finger was incised and drained. An orthopedic specialist diagnosed infectious tenosynovitis of the flexor tendon of the left index finger. The initial slide preparation was negative for AFB. A wound culture was sent to Michigan Department of Community Health, Bureau of Laboratories.

The patient was discharged and then readmitted to the hospital 12 days later with subcutaneous infection at the puncture site, which was again incised and drained. A slide made of growth from the broth culture medium was positive for AFB. Genetic probe results confirmed M. tuberculosis complex. By December 7, 2004, the culture was reported as resistant to pyrazinamide, suggesting M. bovis, which was later confirmed on the basis of susceptibility to thiopene-2-carboxylic acid hydrazide and biochemical testing for pyrazinamidase. The result of a second skin test, 14 weeks postexposure, was positive (6-mm induration). He continued to receive antimicrobial drug therapy for 9 months without further complications

Figure

Figure. Photo of the chest cavity of a deer shot by patient 2; the deer was retrieved after being buried for 9 weeks. The photo shows the classical nodular lesions of Mycobacterium...

As an experienced hunter, patient 2 recognized the tan nodules in the deer’s chest cavity as M. bovis and promptly buried the carcass. In December, he led Michigan Department of Natural Resources staff back to the carcass, which was retrieved; the chest cavity was filled with lesions (Figure). Although the carcass was buried for >9 weeks, chest cavity samples were submitted for culture. After numerous attempts with alternative decontamination techniques, a viable culture was obtained. Genotyping results of the carcass isolate were identical to that recovered from patient 2 and the circulating deer/cattle strain (Table 2). The investigation of the infection in patient 2 provided strong evidence of transmission of M. bovis infection from deer to human through percutaneous injection with a contaminated hunting knife. The patient’s history of hunting exposure was essential to diagnosis and treatment of this rare form of TB.