All locatable subjects (n = 94) for whom tuberculosis prevalence had been determined in an earlier study were tested with purified protein derivative (PPD) and control antigens, sputum sampling, and chest x-rays. Of the 46 who had been tuberculin negative (confirmed with control antigens) 3 years earlier, 2 had developed active tuberculosis in the interim and 14 (30%) were tuberculin positive. All had been engaged continuously in migrant farmwork. Lack of access to health care, an institutional feature of migrant farmwork, was significantly associated with primary infection.

No abstract