Longitudinal survey: according to different sites and the former incidence in these areas with the prevalence of filariasis, 5 towns and 5 countries and 18 administrative villages were chos.

Methods: Etiological and entomological methods were applied for the cross-sectional surveillance in all of filarial endemic counties in turn annually and for the consecutive longitudinal surveillance in 6 provincial surveillance sites.

The method includes combination forecasting vertically and adjusting horizontally with load trend based on gray model.

Methods From 1984 to 2002, Cross-sectional survey: survey of activity of permanent residents and mobile population, of mosquito vectors, of serum in human population, and of terminal patients were carried out.