2017—2021年江苏省土源性线虫感染情况监测分析

Analysis of surveillance on soil-transmitted nematode infections in Jiangsu Province from 2017 to 2021

目的了解2017—2021年江苏省土源性线虫感染情况,为制定科学的防治策略提供依据。方法2017—2021年,江苏省每年选取8个县(市、区)作为监测点(固定监测点1个,每年不变;流动监测点7个,每年不同)。各监测点按照东、西、南、北、中等5个地理方位,每个方位抽取1个乡(镇)的1个行政村开展监测调查,每个行政村抽取3周岁以上常住居民不少于200人。采集监测对象粪样约30 g,通过改良加藤厚涂片法(Kato-Katz法,一粪二检)检测虫卵,计算各虫种感染率和感染度。钩虫阳性粪样再用试管滤纸培养法鉴定钩虫虫种。3~9周岁儿童加做透明胶纸肛拭法检测蛲虫感染情况。从固定监测点每村随机抽取5户住户,每户采集1份菜园或田地的土样(≥400 g),其中350 g土样用于钩蚴检测,50 g用于人蛔虫卵检测。感染率的比较采用卡方检验。结果2017—2021年江苏省累计调查41753人,土源性线虫总感染率为0.30%(124/41753)。蛔虫、钩虫、鞭虫和蛲虫的感染率分别为0.13%(56/41753)、0.06%(24/41753)、0.02%(10/41753)和0.08%(34/41753),所有土源性线虫感染者均为轻度感染。固定监测点土源性线虫总感染率为0.37%(21/5699),流动监测点为0.29%(103/36054),二者差异无统计学意义(χ^(2)=0.19,P>0.05)。2017—2021年,土源性线虫总感染率分别为0.26%(22/8549)、0.54%(46/8452)、0.22%(19/8454)、0.37%(30/8189)和0.09%(7/8109),不同年度间感染率差异有统计学意义(χ^(2)=32.88,P<0.01)。13个设区市中,土源性线虫总感染率最高的为连云港市(1.17%,48/4119),其次是宿迁市(0.38%,21/5487)和淮安市(0.36%,11/3040),不同设区市间感染率差异有统计学意义(χ^(2)=137.52,P<0.01)。男性土源性线虫总感染率为0.26%(52/19773),女性为0.33%(72/21980)(χ^(2)=1.47,P>0.05);3~9岁年龄组土源性线虫总感染率最高,为0.86%(35/4093),不同年龄组人群间感染率差异有统计学意义(χ^(2)=53.24,P<0.01);幼托儿童土源性线虫总感染率最高,为1.21%(22/1811),不同职业人群感染率差异有统计学意义(χ^(2)=45.56,P<0.01);学龄前儿童土源性线虫总感染率最高,为1.24%(25/2020),不同文化程度人群感染率差异有统计学意义(χ^(2)=54.96,P<0.01)。2017—2021年共检测田地或菜园土样125份,1份检出钩蚴(镜检鉴定为十二指肠钩蚴),土样钩蚴阳性率为0.8%;未检出蛔虫卵。结论2017年以来江苏省人群土源性线虫病处于极低流行水平,后续应进一步加强对江苏省北部地区的儿童及老人等重点人群的关注。

Objective To understand the current status of soil-transmitted nematode infections in Jiangsu Province from 2017 to 2021,and provide the basis for the formulating scientific prevention and control strategies.Methods From 2017 to 2021,eight counties(cities,districts)in Jiangsu Province were selected as surveillance sites each year(one fixed site,and seven ambulatory sites changed on yearly base).The surveillance sites were randomly selected from five geographical sections in the east,west,south,north and centre,from each of which one township(town)was selected to set up surveillance site therein one administrative village.No less than 200permanent residents over the age of 3 in each administrative village were selected for surveillance.About 30 g of fecal sample was collected from each participant for examining nematode eggs using the modified Kato-Katz thick smear method(two slide-reading each sample),to calculate infection rate and intensity of different species..Hookworm-positive fecal samples were used to identify parasite species by test tube-filter paper culture method.Children aged 3 to 9 years old were additionally examined for Enterobius vermicularis infection by adhesive cellophane swabs method.Five households were randomly selected from each village at fixed surveillance site to collect soil sample(≥400 g)from vegetable garden or field of each household,of which 350 g were used for detection of hookworm eggs,and 50 g for Ascaris lumbricoides eggs.Infection rates were compared between groups using the chi-square test.Results From 2017 to 2021,a total of 41753 people were examined in Jiangsu Province surveillance sites,and found the overall infection rate of soil-transmitted nematodes at 0.30%(124/41753).The infection rates of A.lumbricoides,hookworm,Trichuris trichura and Enterubius vermicularis were 0.13%(56/41753),0.06%(24/41753),0.02%(10/41753)and 0.08%(34/41753)respectively,and all soil-transmitted nematode infections were of mild type.The infection rate of soil-transmitted nematodes at fixed monitoring site was 0.37%(21/5699),while that at mobile monitoring sites were 0.29%(103/36054).There was no significant difference between different sites(χ^(2)=0.19,P>0.05)。From 2017 to 2021,the five-year infection rates of soil-transmitted nematodes were 0.26%(22/8549),0.54%(46/8452),0.22%(19/8454),0.37%(30/8189)and 0.09%(7/8109),respectively,with statistically significant differences in infection rates between years(χ^(2)=32.88,P<0.01).The highest infection rate of soil-transmitted nematodes was seen in Lianyungang(1.17%,48/4119),followed by Suqian(0.38%,21/5487)and Huai’an(0.36%,11/304),with statistically significant differences among the different cities(χ^(2)=137.52,P<0.01).The infection rate was 0.26%(52/19773)in males and 0.33%(72/21980)in females(χ^(2)=1.47,P>0.05).For differences in age groups,the highest infection rate was found in the 3-9 years age group(0.86%,35/4093),with statistically significant differences among the different age groups(χ^(2)=53.24,P<0.01).For differences in occupations,the highest infection rate was found among children in kindergarten(1.21%,22/1811),with statistically significant differences among different occupational groups(χ^(2)=45.56,P<0.01).For education levels,the highest infection rate was found among preschool children(1.24%,25/2020),with statistically significant differences among people with different levels of education(χ^(2)=54.96,P<0.01).A total of 125 soil samples from fields or vegetable gardens were tested from 2017 to 2021,and one hook larva was detected(identified as duodenal hook larva by microscopic examination),with a positive rate of 0.8%for hookworm larva in soil samples,and no eggs of A.lumbricoides were detected.Conclusion The prevalence of soil-transmitted nematode infection in Jiangsu Province has been at a very low level since 2017.In the future,more attention should be paid to the key groups of children and the elderly in the northern part of Jiangsu Provinces.