Abstract:

Objective To understand the current prevalence and control outcomes of soil-transmitted nematode (STN) in Fujian Province to provide scientific basis for and formulating the standard criteria of transmission control and transmission interruption. Methods According to the National Clonorchiasis and Soil-borne Nematode Surveillance Program (provisional version), 29 surveillance sites were selected from 10 cities in Fujian Province from 2017 to 2019. Each surveillance site includes 5 areas evenly distributed geographically in the east, south, west, north and middle, from which one administrative village from one township (town) was selected as the survey site. No less than 200 permanent residents aged 3-years or above were selected from each administrative village. Fecal samples were collected from the enrolled residents and were examined for STN eggs (two slide-reading per sample) using the modified Kato-Katz thick smear method to microscopically estimate infection rate and intensity. The hookworm species was identified by test-tube filter paper incubation. The infection rate between groups was compared by Chi-square test. Results A total of 30 614 local residents were examined for STN infection, showing 326 positives, with an overall infection rate 1.1%. The infection rates of hookworm, Trichuris trichiura and Ascaris lumbricoides were 1.2% (295/30 614), 0.1% (28/30 614) and 0.0% (3/30 614), respectively. The STN infection rate in 2017—2019 was 1.3% (130/9 668), 1.0% (109/10 417) and 0.8% (87/10 529), respectively, showing a yearly decreasing trend, with significant differences between the years (χ ² = 12.79, P < 0.01). Among the ten cities, Sanming, Pingtan and Nanping had the highest infection rates of 13.5% (154/4 343), 2.0% (22/1 113) and 1.6% (49/3 054), respectively. The remaining seven cities had infection rates of less than 1.0%. Among the 295 hookworm infected cases, 71.5% (211/295) were mild infection, 26.4% (78/295) were moderate and 2.0% (6/295) were severe. Among the 28 T. trichiura infected cases, 85.7% (24/28) were mild and 14.3% (4/28) were moderate. Among the 3 A. lumbricoides infected cases, two were mild and one was moderate. No severe infection of T. trichiura and A. lumbricoides was found. The infection rates of STN in male and female were 0.8% (139/14 782) and 1.1% (187/15 832) with statistically significant difference between the gender (χ ² = 4.12, P < 0.05). The highest infection rate was 3.2% (171/5 373) in the age group of ≥ 65 years, and the infection rate increased with age (Z = 30.32, P < 0.01). The infection rate was higher among farmers, with 1.8% (289/15 644) than in other occupations. The difference was statistically significant(χ ² = 187.91, P < 0.01). The highest infection rate was in illiterate residents 1.5% (113/7 351), and the infection rate decreased with higher educational levels (Z = 15.41, P < 0.01). Conclusion From 2016 to 2019, the infection rate of STN and intensity of STN infection in Fujian Province showed a significant decreasing trend. The infection rates in seven cities dropped below 1.0%, reaching the standard of transmission control.