[Long-term surveillance after basic elimination of bancroftian filariasis]

The longitudinal and cross-sectional systemic surveillance have been conducted for 9-11 consecutive years in six counties (cities) of Guangxi Zhuang Autonomous Region after basic elimination of bancroftian filariasis. The two different control regimens had been used with DEC selective treatment followed by mass treatment of all persons and selective treatment followed by taking DEC medicated salt. During the former 6 years, residual microfilaremia cases could still be detected; whereas during the latter 5 years, no microfilaremia cases could be detected at all. The natural infection of vector mosquitoes showed negative. The positive rate of antibody in the populations was reduced to 1.4-5.5% detected by IFAT, reaching to the level of local non-endemic areas. The result indicated that the transmission of filariasis in these areas has been blocked. The authors suggested that a period of 10 years might be appropriate for surveillance after basic elimination of bancroftian filariasis.