An outbreak of tuberculosis in rural Delaware

A total of 35 patients diagnosed with tuberculosis in 1976-1984 were identified as part of a sustained outbreak involving five communities located in southern Delaware. The index case, a 25-year-old black female with sputum smear-positive, cavitary pulmonary tuberculosis, was a sexual partner of three other persons with cavitary pulmonary tuberculosis and a close contact of 10 other persons with tuberculosis. The median age of the 35 patients was 23 years (range 15 months to 77 years), and 13 (37%) were less than 15 years of age. Sixteen patients (46%) were male, and 34 (97%) were black. Pulmonary parenchymal disease was noted in 18 cases (51%), including nine (26%) with cavitary lesions; 11 (31%) had lymphatic disease (hilar and/or mediastinal); five (14%) had pleural disease; and one (3%) had a normal chest radiograph. Infection prevalence (per 100 tested) was 44.7 for close contacts of cases and 18.3 for other than close contacts, and disease prevalence (per 100 tested) was 8.9 and 1.4 for those two groups, respectively. This outbreak highlights several points: Outbreaks of tuberculosis may go undetected for several years; aggressive and complete surveillance and containment efforts are needed to control tuberculosis; and tuberculosis in children and minorities is still a problem in the United States.