Tuberculosis (TB) is a major global health problem, infecting one-third of the world's population and causing approximately 2 million deaths annually. In the United States, TB is an important public health problem, particularly among immigrants whose active TB case rate is 11 times higher than that of nonimmigrants. Other risk factors include HIV infection; living or working in prison, shelters, and long-term care facilities; caring for TB patients; and alcohol/drug abuse.
Primary TB infection is usually asymptomatic in immune-competent adults, generally presenting with only a new positive reaction to TB skin testing. When present, symptoms often include fever, cough, weight loss, malaise and chest pain. Some patients may present with active pneumonitis (which may be mistaken for community-acquired pneumonia) or extra-pulmonary disease.
Children are more likely to present with active early disease, although the presenting symptoms may be subtle even when chest radiographs (CXRs) are abnormal. Presenting symptoms may include fever, cough, wheezing, poor feeding, and fatigue. TB meningitis and military TB (see descriptions below) are more common in children than adults.
Immunocompromised patients are much more likely to develop rapidly progressive primary infections. (All patients with active TB should be evaluated for immune-compromising conditions.) Symptoms may be pulmonary (fever, cough, dyspnea, hemoptysis) or may be extrapulmonary, reflecting early hematogenous spread to the central nervous system or other sites.
Latent tuberculosis infections are asymptomatic with positive tuberculin skin tests (TSTs) and/or positive interferon-gamma release assays (IGRAs). Latent tuberculosis infections will progress to active disease (ie, reactivation TB) in 5% of cases within 2 years of primary infection; an additional 5% will reactivate over their lifetimes. Reactivation rates are much higher in the very young, the elderly, persons with recent primary infection, those with immune compromise (in particular, HIV), and those with chronic diseases such as diabetes and renal failure.
Most patients with reactivation TB present subacutely with fever, malaise, weight loss, fatigue, and night sweats. Most patients with active TB will have pulmonary involvement characterized by subsequent development of productive cough. Hemoptysis, pleuritic chest pain, and dyspnea may develop. Rales and rhonchi may be found, but the pulmonary examination is not usually diagnostic. TB should be considered in any HIV patient with respiratory symptoms, even if chest radiographs are normal (see Chapter 92 HIV and AIDS).
Extrapulmonary TB develops in up to 20% of cases. Lymphadenitis, with painless enlargement and possible draining sinuses, is the most common presentation. Patients may also present with symptomatic pleural effusion, pericarditis, peritonitis, or meningitis. Additional sites of reactivation TB after hematogenous spread include bones, joints, adrenals, GI tract and GU tract. Extrapulmonary reactivation TB is more common and often more severe in young children and immune-compromised patients as noted for primary TB infection above.
Miliary TB is a multisystem disease caused by massive hematogenous dissemination. It ...