The consolidation and surveillance of filariasis after basic elimination in Shangcheng County of Henan Province.

Objective To understand the distribution pattern of residual microfilaremias and endemic dynamics of filariasis so as to speed up the elimination of filariasis in Shangcheng County. Methods In 1975 after filariasis basically eliminated,the study on detection and treatment of residual source of infection, fixed-point observation were conducted, consolidating measures such as mass administration of medicated salt, treatment chronic patient, and mosquito control by spraying pyrethroid and DDT were carried out. Then surveillance activities on etiology, serology and mosquito vector were conducted. Results From 1976 to 2002, a total of (169 415) and 10 864 persons were screened in cross-sectional and target population etiological surveillance and 899 and 188 residual microfilaremia were detected out. 18 037 mosquitoes in human rooms were examined in cross-sectional surveillance and 19 mosquitoes infected were detected. No positive mosquitoes were found since 1982. Longitudinal surveillance: From 1975 to 1985,(16 611)persons were screened in the fixed-point observation and 95 residual microfilaremia were detected,11 805 mosquitoes in human rooms were examined and 2 mosquitoes infected was detected in 1987. No positive mosquito were found since 1978. From 1988 to 2000, 6 807 persons and 53 691 mosquitoes in human rooms were examined in longitudinal surveillance point but neither microfilaremia nor infected mosquito were found. The serological surveillance of 847 persons, and no positives were detectied. From 1989 to 2002, no microfilaremia and infected mosquitoes were detected in surveillance activities. Conclusion Consolidating measures taken in Shangcheng after filariasis basically eliminated were effective and the objective of long term control has been achieved.