Abstract: Objective To understand the current situation and trend of soil-transmitted nematode infection in Sichuan Province from 2016 to 2021, and to provide scientific basis for formulating the control strategies of soil-transmitted nematode disease. Methods From 2016 to 2021, 4 fixed and 136 mobile were set up in 140 counties (cities, districts) in Sichuan Province. The surveillance sites were assigned to five areas according to geographical location of east, west, south, north and central. One administrative village (community) of one township (town, street) was randomly selected from each geographical area, and no less than 200 permanent residents over age 3 in the survey year was cluster sampled from each administrative village. The fecal samples of participants were collected, and examined for intestinal nematode eggs using modified Kato thick smear method (two slide-reading each sample). χ² test was used to compare the infection rate between groups. Results A total of 165 551 people were surveyed, and the overall infection rate was 7.02% (11 614/165 551). The infection rate in each year was 8.19% (2 946/35 985), 7.75% (2 675/34 520), 8.14% (1 654/20 316), 8.05% (2 518/31 292), 3.57% (937/26 264), 5.15% (884/17 174), respectively (χ² = 415.370, P < 0.05). The infection rate of hookworm, ascaris and trichuris was 5.63% (9326/165 551), 1.04% (1730/165 551) and 0.60% (993/165 551), respectively. Among the five types of landform in Sichuan Province, the infection rate of soil-transmitted nematodes among people in hilly areas was the highest, being 9.42% (7 648/81 168); the infection rate in northwest Sichuan plateau is the lowest, which was 1.8% (205/11 406) (χ²=1 771.185, P < 0.05). The infection rates of soil-transmitted nematodes in males and females was 6.84% (5 389/78 777) and 7.17% (62 225/86 774), respectively (χ² = 7.018, P < 0.05). Among different age groups, the infection rate of soil-transmitted nematodes in the 70-79 age group was the highest, which was 11.85% (2 319/19 569) (χ²=2 056.363, P < 0.05). Among people with different education levels, the infection rate of soil-transmitted nematodes in illiterate people was the highest at 10.04% (2 133/21 244)(χ² = 994.429, P < 0.05). Among different occupational groups, the infection rate of soil nematode was the highest, which was 7.93%(9 921/125 079) in farmers(herdsmen and fishermen) (χ² = 734.068, P < 0.05). Among different ethnic groups,the infection rate of soil-transmitted nematodes in the Yi ethnic group was the highest, which was 19.48% (890/4 569) (χ² =1 638.694, P < 0.05). Conclusion From 2016 to 2021, the infection rate of soil-transmitted nematodes in Sichuan Province showed a downward trend, mainly hookworm infection. Hilly areas and mountainous areas in southwestern Sichuan had higher infection rate and are key areas to prevention and control. Women, older people, people with lower education level and Yi ethnic group had higher infection rate, and are the key groups to prevention and control populations.

Key words: Soil-transmitted nematode, Endemic statue, Sichuan province