DNA fingerprinting and molecular epidemiology of tuberculosis: Use and interpretation in an epidemic setting

Tuberculosis (TB) is still a major cause of morbidity and mortality. It is clear that control requires more than simple availability of antibiotics. I n order to gain insight into the disease, DNA fingerprinting has been appli ed to the study of bacterial population structure. This technology has been used to quantitate various components of the disease in a high-incidence c ommunity, viz. recent transmission (RT) and reactivation (RA) and to monito r these over time as a tool to quantitate changes in the epidemic. In our h igh-incidence community, we find unexpectedly high strain diversity, lower than predicted RT, and that reactivation disease dominates. This technology can be used to examine and challenge traditional dogmas. Quantitative meas ure of RT varies over time, using a two-year sliding window for estimation as a useful period. The results show that the "epidemic" consists of subepi demics characterized by strain families that wax and wane in the community of TB patients. The technology is shown to be a useful and quantitative too l to assess disease status and can therefore be used to monitor interventio n strategies and refine and monitor results of new control measures.