关键词: 土源性线虫病, 感染, 传播控制与阻断, 监测

Abstract:

Objective To investigate the prevalence and epidemiological characteristics of soil-transmitted helminth (STH) infections in China in 2021, so as to provide data support for improving soil-transmitted helminthiasis control strategies in high-prevalence areas and implementing transmission control and interruption of soil-transmitted helminthiasis in low-prevalence areas. Methods National surveillance on soil-transmitted helminthiasis was performed in 412 surveillance counties across 31 provinces (municipalities and autonomous regions) in China in 2021. Each surveillance county was divided into eastern, western, southern, northern, and central parts according to geographical locations, and one administrative village was sampled from one township in each part. Then, 200 permanent residents over 3 years old were sampled from each administrative village, and at least 1 000 residents of different age groups were recruited in each surveillance county. Subjects’ stool samples were collected for detection of STH eggs using a modified Kato-Katz thick smear method (two smears from one stool). In addition, 5 households were randomly sampled from each administrative village, and soil samples were collected from their farmlands or vegetable gardens to detect hookworm larvae and Ascaris lumbricoides eggs. Comparisons of proportions were done with the Chi-square test. Results A total of 424 306 residents were investigated in 412 soil-transmitted helminthiasis surveillance counties across China in 2021, and the overall prevalence of STH infections was 0.88% (3 730/424 306), with 0.67% (2 845/424 306) of hookworm infection, 0.11% (461/424 306) of A. lumbricoides infection and 0.12% (526/424 306) of Trichuris trichura infection, respectively. The highest prevalence of STH infections was demonstrated in Yunnan Province (5.74%, 917/15 967), the highest prevalence of hookworm infection was also in Yunnan Province (4.93%, 787/15 967), the highest prevalence of A. lumbricoides infection was in Qinghai Province (0.52%, 32/6 106), and the highest prevalence of T. trichura infection was in Hainan Province (1.10%, 46/4 184). The prevalence of STH infections was higher in females (0.94%, 2 052/217 245) than in males (0.81%, 1 678/207 061) (χ² = 21.90, P < 0.01), and the highest prevalence of STH infections was shown among residents aged over 60 years (1.62%, 1 921/118 413) (χ² = 1 175.93, P < 0.01). The proportions of light-intensity infections in hookworm, A. lumbricoides and T. trichura were 92.16% (2 622/2 845), 90.46% (417/461) and 93.54% (492/526), and the proportions of moderate infections were 4.04% (115/2 845), 9.54% (44/461) and 6.08% (32/526). There were 108 residents detected with heavy-intensity hookworm infections (3.80%, 108/2 845), and 2 participants with heavy-intensity T. trichura infections (0.38%, 2/526); however, no heavy-intensity A. lumbricoides infection was found. A. lumbricoides eggs were detected in 73 out of 2 475 households of soil samples (2.95%, 73/2 475), and hookworm larvae were identified in 58 households of soil samples (2.34%, 58/2 475). Both A. lumbricoides eggs and hookworm larvae were detected in soil samples from farmlands and vegetable gardens. In addition, the detection rates of Necator americanus and Ancylostoma duodenale larvae were 1.86% (46/2 475) and 0.40% (10/2 475), respectively. Conclusion The prevalence of STH infections was reduced to less than 1% in national surveillance counties of China in 2021; however, it varied greatly in regions. More attention is required to be paid to residents at ages of over 60 years and females. Precise control strategies tailored to local circumstances are recommended, and initiation of transmission control and interruption of soil-transmitted helminthiasis is encouraged in low-prevalence areas.

Key words: Soil-transmitted helminthiases, Infection, Transmission control and interruption, Surveillance