Prediction of elimination of leprosy in leprosy endemic areas of China.

A study was carried out based upon the data from the National System for Leprosy Surveillance and using appropriate mathematical models. The results showed that of 337 counties where the national goal of basic eradication of leprosy had not been reached and in 40 counties where the WHO goal of leprosy elimination had not been achieved in 1996, the detection rates in calendar years followed exponential models with significant goodness-of-fit. In the 67 counties with downward trends of detection rates, the national goal can be met in terms of detection rate in 6% of counties before the year 2000 or 34.4% before the year 2010, or, in terms of prevalence rate in 31.3% before the year 2010. In the 11 counties with downward trends of the detection rates, the WHO target can be met in eight to ten counties within this century when the duration of disease was determined with the WHO definition. If the MB proportion among new cases increased by 10%, the target would be met one year later. However, at the same MB proportion, the change of fixed treatment schedules from PB six months and MB two years to PB nine months and MB three years will cause achievement of the goal to be postponed by two to ten years.