Active case finding: understanding the burden of tuberculosis in rural South Africa

SETTING: The Agincourt demographic and health surveillance site in South Af rica's rural Northern Province. OBJECTIVES: To accurately assess the true burden of tuberculosis in a rural sub-district with a known high prevalence of human immunodeficiency virus. DESIGN: Data on hospital registrations of tuberculosis were combined with d ata from an ongoing demographic health and surveillance system to accuratel y describe the burden of tuberculosis in a well-defined community. Undiagno sed active cases of sputum-positive disease in the community were detected among chronic coughers identified by heads of household during a single-pas s census interview. RESULTS: The incidence of hospitalised tuberculosis among the permanently r esident population (n = 56 566) was 212/100 000 person-years during 1999. T he average point prevalence of detected tuberculosis tall forms) among pati ents aged over 10 years was 133/100 000, and 81/100 000 for sputum-positive pulmonary disease. This compares with a point prevalence of 16/100 000 cas es of sputum-positive disease detected through active case finding. CONCLUSION: For every nine cases of sputum positive pulmonary tuberculosis being treated at any one time, there are two cases of undiagnosed disease i n the community. This study demonstrates a modest burden of undiagnosed tub erculosis among residents in a rural sub-district in South Africa.