Table 1. Key Differences Between Active and Latent Tuberculosis Infections
ActiveLatent
Estimated numbers, 2012
    Global2,48.6 million people per year; 1.3 million deaths per year2 billion people
    United States7,9,109,945 tuberculosis cases (rate of 3.2 cases per 100,000 people)10 to 15 million people
Clinical presentation4,5Usually symptomaticAsymptomatic
Depends on primary disease, but usually includes persistent cough (>2 weeks); fever; night sweats; unexplained weight loss; fatigue; dyspnea; hemoptysis; chest pain; pleuritic pain
Chest radiograph4,11Usually abnormal radiographic imagingNormal radiographic imaging
Depends on primary disease, but usually includes the following:

  • If primary (recent) infection: middle or lower lobe infiltrates, ipsilateral hilar adenopathy, or cavitation

  • If secondary (reactivation) infection: upper lobe infiltrates or cavitation

  • If healed (previous) infection: hilar or upper lobe dense pulmonary nodules, with or without visible calcification