蛔虫病是全球热带和亚热带地区的一种常见传染病;估计有 8.07 亿至 12.21 亿人被感染,其中约有 5 亿人生活在中国。[2]Bethony J, Brooker S, Albonico M, et al. Soil-transmitted helminth infections: ascariasis, trichuriasis, and hookworm. Lancet. 2006;367:1521-1532.http://www.ncbi.nlm.nih.gov/pubmed/16679166?tool=bestpractice.com[4]de Silva NR, Brooker S, Hotez PJ, et al. Soil-transmitted helminth infections: updating the global picture. Trends Parasitol. 2003;19:547-551.http://www.ncbi.nlm.nih.gov/pubmed/14642761?tool=bestpractice.com在此全球队列研究中,大约 5,900 万人存在并发症风险,每年有 200,000 人遭遇威胁生命的急性事件。[3]de Silva NR, Chan MS, Bundy DA. Morbidity and mortality due to ascariasis: re-estimation and sensitivity analysis of global numbers at risk. Trop Med Int Health. 1997;2:519-528.http://www.ncbi.nlm.nih.gov/pubmed/9236818?tool=bestpractice.com[7]de Silva NR, Guyatt HL, Bundy DA. Morbidity and mortality due to Ascaris-induced intestinal obstruction. Trans R Soc Trop Med Hyg. 1997;91:31-36.http://www.ncbi.nlm.nih.gov/pubmed/9093623?tool=bestpractice.com
在过去一个世纪中,美国农村地区蛔虫病的发病率从估计的 75% (肯塔基州东部的布雷萨特郡)开始下降。[8]Hotez PJ. Neglected infections of poverty in the United States of America. PLoS Negl Trop Dis. 2008;2:e256.http://www.plosntds.org/article/info%3Adoi%2F10.1371%2Fjournal.pntd.0000256http://www.ncbi.nlm.nih.gov/pubmed/18575621?tool=bestpractice.com最近分别对肯塔基州和佛罗里达州两个地区在二十世纪七、八十年代的发病情况进行了研究,发现这两个地区报告的学龄儿童发病率分别在 14% 至 32% 之间。[9]Walzer PD, Milder JE, Banwell JG, et al. Epidemiologic features of Strongyloides stercoralis infection in an endemic area of the United States. Am J Trop Med Hyg. 1982;31:313-319.http://www.ncbi.nlm.nih.gov/pubmed/7072896?tool=bestpractice.com[10]Adams RT, Perkin JE. The prevalence of intestinal parasites in children living in an unincorporated area in rural northern Florida. J Sch Health. 1985;55:76-78.http://www.ncbi.nlm.nih.gov/pubmed/3844579?tool=bestpractice.com据估计,1987 年整个美国的发病率为 0.8%。[11]Kappus KD, Lundgren RG Jr, Juranek DD, et al. Intestinal parasitism in the United States: update on a continuing problem. Am J Trop Med Hyg. 1994;50:705-713.http://www.ncbi.nlm.nih.gov/pubmed/8024063?tool=bestpractice.com在经济发达国家中,来自发展中国家的新近移民和收养的儿童中也发现了蛔虫病。
降雨后,含有粘土的土壤有利于蛔虫卵的存活和散布。由于虫卵也能耐受冷冻,因此感染可扩展至北温带。似乎只有在寒冷、干燥的气候中不会感染。卫生、教育、社会经济状况以及是否能获得医疗服务是影响特定人群感染可能性的额外因素。与成人相比,高虫荷更常见于儿童。[1]Seltzer E, Barry M, Crompton DWT. Ascariasis. In: Guerrant RL, Walker DH, Weller PF, eds. Tropical infectious diseases: principles, pathogens and practice. 2nd ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2006:1257-1264.[12]Cooper PJ. Interactions between helminth parasites and allergy. Curr Opin Allergy Clin Immunol. 2009;9:29-37.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2680069/http://www.ncbi.nlm.nih.gov/pubmed/19106698?tool=bestpractice.com暴露于自给农业地区的学龄前儿童感染强度更高。[13]Krause RJ, Koski KG, Pons E, et al. Ascaris and hookworm transmission in preschool children in rural Panama: role of subsistence agricultural activities. Parasitology. 2016;22:1-12.http://www.ncbi.nlm.nih.gov/pubmed/27000494?tool=bestpractice.com