Study on the characteristics and correlation factors of soil-transmitted nematode infections in Shanxi Province

Objective The study was conducted to explore the distribution and variation of soil-transmitted nematode infections in Shanxi and analyze the risk factors in order to provide scientific basis for further development of parasite preventive strategies.Methods The sample size in the province was determined according to the estimated population rate by a formula.Target counties(districts)were selected according to the geographic features and economic condition by stratified sampling,where target villages were selected by random cluster sampling as previously investigated villages being the reserve sampling points.Questionnaires were used in the field investigation and modified Kato-Katz method of thick smear was applied to microscopically detect the nematode eggs.Enterobius vermicularis eggs were collected by polishing around the anuses for children.Chi-square test and Logistic regression analysis were conducted in SPSS Software.Results 7500 samples were studied in the survey.The infection rates of soil-transmitted nematodes,Ascaris and Enterobius were respectively 5.67%,2.89% and 2.85%,while the infection rate of Enterobius in children under 12 years old was 7.96%.Only one case of Trichuris trichiura was found and no case of ancylostome was detected.Geographical distribution:the infection rates of Ascaris in Yuncheng(5.75%)and Luliang(5.54%)City were relatively higher,so were the infection rates of Enterobius in Jincheng(6.27%)and Yangquan(4.88%)City.Age distribution:the infection rate of soil-transmitted nematodes,Ascaris and Enterobius declined as the age increased,especially Enterobius.Working on bare feet,drinking raw water,eating food fell on the floor but not washed completely,eating raw vegetables,fruits and water chestnut,high family income were risk factors of Ascaris infection through Logistic regression analysis.Conclusion The infection rate of soil-transmitted nematodes was relatively low in Shanxi with an obvious declining trend.However,the infection rate among the youth and children was still high,especially in high temperature areas with bad sanitation conditions.Poor hygienic habit led to Ascaris infections.