Abstract: 　Objective Twenty-six species of human parasites were recorded in Zhejiang Province in 1987-1989 as a part of the national investigation on the distribution of human parasites, and the total prevalence was 80.2%. In order to find out possible changes on the composition of parasite species and decrease of prevalence after control intervention particularly mass chemotherapy in the past years and provide evidence for an improved control strategy, the second sampled survey was carried out from 1998 to 1999. Methods Ten counties were identified randomly out of 28 counties where the last survey was conducted following the same sampling method. Same technics were used for case detection and data processing. Results The total \{infection\} rate in a sample of 15 698 was 22.84% in 30 investigation spots in 10 counties, and 17 species of parasites were \{revealed\}. The overall prevalence was reduced by 71.51% in comparison to that of 1989, and the number of parasite species was 17, 9 less than that of the last investigation. Conclusions The prevalence of human parasites has greatly declined in this province due to the socioeconomic development and adoption of comprehensive control measures focusing on mass chemotherapy in the past decade.

Key words: parasite, prevalence, epidemiological investigation