目的 了解我国2021年土源性线虫感染情况和流行特征，为高流行地区完善防治策略、低流行地区开展传播控制和阻断提供数据支持。 方法 2021年在31个省（自治区、直辖市）的412个监测点（县）开展监测工作。监测点（县）根据地理方位划分为东、西、南、北、中5个片区，每个片区各抽取1个乡（镇）的1个行政村，每个行政村抽取3周岁以上常住居民200人，每个监测点包括各年龄组人群不少于1 000人。采集以上人群粪样，采用改良加藤厚涂片法（一粪两检）检测土源性线虫虫卵。每个行政村随机抽取5户，采集田地或菜园土样，检测土样中钩蚴和人蛔虫卵。感染率的比较采用卡方检验。 结果 2021年，全国412个土源性线虫病监测点共调查424 306人，土源性线虫感染率为0.88%（3 730/424 306）。其中，钩虫感染率为0.67%（2 845/424 306），蛔虫感染率为0.11%（461/424 306），鞭虫感染率为0.12%（526/424 306）。土源性线虫感染率最高的省份为云南（5.74%，917/15 967）。钩虫、蛔虫和鞭虫感染率最高的省份分别为云南（4.93%, 787/15 967）、青海（0.52%，32/6 106）和海南（1.10%，46/4 184）。女性土源性线虫感染率（0.94%，2 052/217 245）高于男性（0.81%，1 678/207 061）（χ² = 21.90，P < 0.01）。≥ 60岁组土源性线虫感染率最高（1.62%，1 921/118 413）（χ² = 1 175.93，P < 0.01）。钩虫、蛔虫、鞭虫轻度感染者比例分别为92.16%（2 622/2 845）、90.46%（417/461）和93.54%（492/526）；中度感染者比例分别为4.04%（115/2 845）、9.54%（44/461）和6.08%（32/526）。钩虫重度感染者有108人（3.80%，108/2 845），鞭虫重度感染者有2人（0.38%，2/526），未发现蛔虫重度感染者。共检测2 475户土样，73户检出人蛔虫卵，检出率为2.95%（73/2 475）；58户检出钩蚴，检出率为2.34%（58/2 475）。田地和菜园的土样中均发现了人蛔虫卵和钩蚴。美洲板口线虫、十二指肠钩口线虫钩蚴的检出率分别为1.86%（46/2 475）、0.40%（10/2 475）。 结论 2021年全国监测点人群土源性线虫感染率已降至1%以下，但地区分布差异较大，需要重点关注60岁以上人群和妇女。应针对不同流行情况，采用精准防控策略，并鼓励低流行地区启动传播控制与阻断工作。

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.