类圆线虫见于世界范围内的热带和亚热带地区。感染在美国阿巴拉契亚地区和某些地中海地区(如西班牙加泰罗尼亚)也广为流行。[1]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来自发展中国家/地区的移民和难民的风险最大,抵达美国的新移民的感染率为 5%~10%。[2]Genta RM. Global prevalence of strongyloidiasis: critical review with epidemiologic insights into the prevention of disseminated disease. Rev Infect Dis. 1989;11:755-767.http://www.ncbi.nlm.nih.gov/pubmed/2682948?tool=bestpractice.com[3]Nutman TB, Ottesen EA, Ieng S, et al. Eosinophilia in Southeast Asian refugees: evaluation at a referral center. J Infect Dis. 1987;155:309-313.http://www.ncbi.nlm.nih.gov/pubmed/3805765?tool=bestpractice.com东南亚人的感染率最高。最初的人类感染是通过生活在受感染土壤里的幼虫穿透皮肤(通常是足部皮肤)发生。与土壤接触的人群(如农民和农业工作者)面临更大的风险。[4]Román-Sánchez P, Pastor-Guzmán A, Moreno-Guillén S, et al. High prevalence of Strongyloides stercoralis among farm workers on the Spanish Mediterranean coast. Analysis of the predictive factors of infection in developed countries. Am J Trop Med Hyg. 2003;69:336-340.http://www.ajtmh.org/cgi/content/full/69/3/336http://www.ncbi.nlm.nih.gov/pubmed/14628954?tool=bestpractice.com因此,男性受累的风险约比女性高 2~3 倍。[5]Jongwutiwes U, Waywa D, Silpasakorn S, et al. Prevalence and risk factors of acquiring Strongyloides stercoralis infection among patients attending a tertiary hospital in Thailand. Pathog Glob Health. 2014;108:137-140.http://www.ncbi.nlm.nih.gov/pubmed/24766337?tool=bestpractice.com短期国际游客通常面临低风险,除非他们赤脚接触受感染土壤或沙子。第二次世界大战、朝鲜战争或越南战争期间曾在东南亚服役的退伍军人面临该风险;战俘的风险尤其高。[6]Gill GV, Welch E, Bailey JW, et al. Chronic Strongyloides stercoralis infection in former British Far East prisoners of war. QJM. 2004;97:789-795.http://qjmed.oxfordjournals.org/cgi/content/full/97/12/789http://www.ncbi.nlm.nih.gov/pubmed/15569810?tool=bestpractice.com