Tuberculosis epidemiology and control in Veracruz, Mexico

Background Tuberculosis (TB) rates remain high in regions of Southern Mexic o despite the existence of a National Tuberculosis Program. Understanding T B epidemiology in such settings would assist in thr design of improved TB c ontrol and highlight the challenges confronting TB control in developing co untries. Methods We conducted a retrospective review of treatment control cards from 1991 to 1994 in five municipalities in a semiurban region of Southern Mexi co. Results The relatively high rate of TB observed, 42.6 per 100 000 inhabitan ts, did not change significantly during the study period. Cure rates among new cases were 79% and significantly lower among retreatment cases (62%). D irectly observed therapy (DOT) was administered to 84% of patients. Approxi mately one-half of the retreatment cases who were not cured were compliant with therapy, suggesting that drug resistance contributed to these poor res ults. Of particular concern was a core group of 16 patients who had receive d at least three treatments. Conclusions This region of Mexico has persistently high TB rates despite a DOT-based TB control programme which achieves an overall cure rate of 77%. There exist many retreatment cases for whom cure rates are significantly lo wer. These cases may serve as a core group for the dissemination of drug re sistant TB. The control programme is being reinforced by a nominal register of patients, decreasing administrative barriers for drug supply to individ ual patients and the availability of mycobacteria cultures. In addition to these measures, in regions which are approaching the levels of efficacy rec ommended by the WHO it may be appropriate to consider focusing efforts on t he identification and treatment of chronic cases.