Soil-transmitted helminthiases: nationwide survey in China.

A total of 2848 study sites, with about 500 people in each, were randomly sampled for this investigation which covered a total population of 1 477 742. By stool examinations using the Kato-Katz thick-smear and larval-culture techniques, overall prevalences of 47.0%, 18.8%, and 17.2% were obtained for Ascaris lumbricoides, Trichuris trichiura, and hookworm infections, respectively. The number of infections due to Ascaris, Trichuris, and hookworm was estimated as 531 million, 212 million, and 194 million, respectively. Egg counts showed that 75-95% of the subjects had light infections. Higher prevalences of ascariasis and trichuriasis were found in the age group of 5-9, 10-14 and 15-19 years, and among adults for hookworm. Students, farmers (including vegetable growers) and fishermen were the occupational groups with high infection rates. The prevalence of helminthiases was found to be closely associated with climatic and geographical factors. In view of the morbidity and mortality due to these helminthiases, their control, particularly in schoolchildren, is very important.