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FINDINGS: Lymphadenitis (usually cervical) is the most common form of extra-pulmonary TB in developing countries. CNS infections include meningitis and tuberculomas of the brain and spinal cord. Findings in renal tuberculosis include hematuria, pyuria, flank pain, and positive AFB stains of the urine sediment. Abdominal TB is still common in developing countries. The clinical presentation may include gastrointestinal bleeding, fever, abdominal mass, bowel obstruction, and acute abdomen secondary to perforation. Rarely, TB patients develop eye infections (uveitis or oculoglandular conjunctivitis); skin infections (nodules or warty growths); or infections of the larynx, sinuses, salivary glands, and adrenal glands. Other complications of TB include pericarditis, epididymo-orchitis, female genital tract infections, arthritis, and osteomyelitis. Pott's disease involves two adjacent vertebral bodies with narrowing of the intervertebral disc. Miliary TB affects the bone marrow (anemia and thrombocytopenia) and the lungs (dyspnea). Chronic TB is associated with hypergammaglobulinemia. EPIDEMIOLOGY: M. tuberculosis infects 1/3 of the world�s population and causes 8 million new cases and 2 million deaths per year. Healthcare workers are exposed to tubercle bacilli in airborne droplet nuclei while caring for patients with tuberculosis and while performing bronchoscopies, autopsies, and endotracheal intubations on these patients. Approximately 90%-95% of those newly infected with tuberculosis never develop clinical illness. These individuals have a latent infection that may persist for a lifetime. Silicosis and other debilitating diseases can impair the immune system and increase the risk for activation of latent tuberculosis. In some sub-Saharan areas of Africa, 10%-15% of adults are co-infected with HIV and TB. To become infected, one must breathe the air contaminated by a coughing patient with active TB. The likelihood of infection increases as the exposure period extends longer than just a few minutes or a few hours, e.g., attending to a patient with active TB in a hospital, prison, or homeless shelter. TB is transmitted rarely by direct contact with infected tissues, e.g., a pathologist with a "prosector's wart." The only reservoir for M. tuberculosis is other humans. Rarely, the disease spreads through infected monkeys, cattle, badgers, swine, and other mammals. TB from milk infected with M. bovis is no longer seen in developed countries because of pasteurization and skin testing of dairy herds. [Merck Manual, p. 1091, 1508-18; CCDM, p. 560-72; CDC Travel, p. 339-40; Guerrant, p. 394-407, 1452, 1567-8, 1576-7; PPID, p. 2852-86] Pulmonary tuberculosis in South African gold miners is an epidemic associated with both HIV infections and silicosis. In a study of 520 gold miners, TB was associated with silica exposure, even in the absence of silicosis. [PMID 16497860] |
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