Abstract:

Objective To understand the current status of soil-transmitted helminth (STH) infection and control effect in Henan Province, for providing basis for formulating prevention and control countermeasures. Methods From 2016 to 2020, surveillance sites were set up in selected counties in Henan Province, according to the National Surveillance Program for Liver Fluke Diseases and Soil-transmitted Nematodes (Pilot). The surveillance counties were selected from five areas (east, west, south, north and central) of the province. From each of the areas, a township was randomly selected, and then an administrative village was selected from each township as the surveillance site. Over 200 permanent residents above 3 years old were cluster sampled from each administrative village and no less than 1 000 residents were included in each surveillance county. Fecal samples were collected from the participants for examining and counting STH eggs using modified Kato-Katz thick smear method to calculate infection rate. Hookworm egg positive samples were further identified for species by test tube-filter paper culture method. The infection rate between groups was compared by the Chi-square test. Results A total of 101 254 participants were enrolled in the surveillance from 98 surveillance sites, of them, 139 were found STH positive, with an overall infection rate of 0.1% in Henan Province. The total infection rate of STH in each year was below 1.0% (0.08%-0.19%), and the difference was statistically significant (χ² = 9.797， P < 0.05). The linear trend test showed that the total infection rate of STH has no significant difference (χ² = 1.304， P > 0.05). Among the 18 cities and 6 counties, the top infection rates were seen in Luohe (0.46%, 19/4 097), Nanyang (0.31%, 32/10 280) and Jiyuan Demonstration Zone (0.28%, 3/1 073), and no infection was found in 7 cities (counties). The infection rates of STH in males and females were 0.14% (65/47 795) and 0.14% (73/53 459). There were no significant differences in hookworm, Ascaris lumbricoides, Trichuris trichiura and total infection rates among different genders (male: 0.07%, 0.05%, 0.02%, 0.14%; female: 0.07%, 0.05%, 0.01%, 0.14%) (χ² = 0.117, 0.001, 0.526, 0.001; P > 0.05). The infection occurred in all age groups, with the highest infection rate in the group aged ≥ 71 years of 0.4% (27/6 603). The hookworm infection rate was the highest among the ≥ 71 years age group, at 0.24% (16/6 603). The infection rates of soil-borne nematodes, hookworm, A. lumbricoides, T. trichiura among different age groups were statistically significant (χ² = 83.585, 69.061, 16.269 and 26.559; P < 0.01 or P < 0.05). Among different occupation groups, farmers had the highest infection rate at 0.2% (104/52 276). Among different education groups, the illiteracy or semiilliteracy group had the highest infection rate at 0.14% (10/6 939). There were significant differences in the infection rate among different ages, occupations and educational background (χ² = 83.585, 32.330, 20.014; P < 0.01). There were significant differences in hookworm infection rates among people of different occupations and cultures (χ² = 31.103 and 16.605, P < 0.01), but there were no significant differences in A. lumbricoides, T. trichiura infection rates among the groups (χ² = 6.383, 4.658, 2.819, 9.366; P > 0.05). Conclusion From 2016 to 2020, the infection rate of STH in Henan Province decreased significantly and remained at a considerably low level, showing sporadic distribution. Residents at age 61 and above, farmers, people with the education of primary or middle school, illiterate or semiilliterate are the main targets of control program.

Key words: Soil-transmitted helminth, Infection, Surveillance, Henan Province