Drug resistant tuberculosis in sub-Saharan Africa: An estimation of incidence and cost for the year 2000

Objectives: To evaluate the tuberculosis (TB) drug resistance in Rwanda on smear positive sputa, collected prospectively at the start of the National TB programme, before the start of any treatment or retreatment. To adapt the scenarios of Schulzer et al (1992) to the data from Rwanda, in order to obtain an estimation of the number of drug resistant and multi-drug resistant (MDR) TB cases expected by the year 2000. Design: A total of 298 specimens (236 randomly selected new cases and 62 retreated cases), collected between January 1991 and June 1993, were sent to Belgium in 1% cetylpyridinium chloride. Drug resistance was determined using the proportion method. Results: MDR, i.e. resistance to at least rifampicin (R) and isoniazid (H), was observed in 3 (1.3%) out of 236 new cases and in 4 (6.5%) out of 62 retreated cases. For new cases, single drug resistance to H, R and ethambutol (E) was 3%, 0.4% and 4.2% respectively; for retreated cases it was 14.5%, 1.6% and 6.5% respectively. Based on the estimate of the size of the TB problem in sub-Saharan Africa by the year 2000 (Schulzer), we calculated that the region should expect between 15 543 and 223 417 cases of MDR, all forms combined (between 2.3 and 32.7 per 100 000 inhabitants), by the end of the century. Conclusion: The results from Rwanda during the period studied do not appear dramatic. However, for some other developing countries, they may just represent the tip of the iceberg. Rapid recognition of resistance to the major antituberculosis agents is essential for control of TB. Integration of an MDR increase factor into the TB budget would not dramatically increase the total TB budget. Our data urgently point to the need for drug resistance surveys, followed by continuous drug resistance monitoring in high TB prevalence areas.