Epidemiology and control of tuberculosis in Taipei

This retrospective study evaluated epidemiological trends in tuberculosis and the performance of a TB control program in Taipei.

Data of all recorded tuberculosis cases from 1994 through 2000 obtained from the Tuberculosis Registry Center was used to analyze the trend of incidence. Tuberculin skin tests were also performed to estimate the prevalence and annual risk of tuberculosis infection in second-grade schoolchildren during the period 1996-1999. The management cards for all tuberculosis patients from 1992 to 1996 obtained from Taipei Municipal Chronic Disease Hospital were also reviewed.

The results show that incidence of tuberculosis had an increasing trend during the study periods with an average annual increase of 7.73% and 9.93% for males and females, respectively. Age-specific incidence showed a similar trend with a clear predominance of cases occurring in patients aged 25-34 and 65+ years. This bimodal pattern became more apparent in 2000. In second-grade schoolchildren, the annual risk of tuberculosis infection was approximately 0.68% with a decreasing trend over the study period. The relatively low cure rate of TB, averaging 47.2%, did not change significantly during the study period. Cure rate was significantly associated with patient's age, patient status as a new or recurrent case, and the development of side effects due to treatment with antituberculosis drugs.

Because of the low overall cure rate of 47.2%, this region of Taipei remains high TB rates. The inefficiency of the existing tuberculosis control program is largely to blame for the alarmingly high rates. The high percentage of recurrent cases and of cases in individuals aged 25-34 and older than 65 present a severe challenge to effective management and form a chronic pool of infectious cases. Our findings suggest that in order to achieve the WHO target of cure in 85% of TB cases, focusing effort on the identification and treatment of these groups is mandatory.