, commonly known as threadworm, is a soil-transmitted human parasite belonging to a group of nematodes called roundworms. Although prevalent almost worldwide, except only in the far north and south, the global burden of this parasitic infection is still underestimated because of the unavailability of precise data from endemic areas. therefore, becomes one of the most overlooked parasitic infections among the "neglected tropical diseases" (NTDs). The helminth, mainly infects humans but also occurs naturally in domestic dogs, cats, and primates. The feature that makes it unique among other human nematodes is the ability to give rise to a progeny of free-living worms from rhabditiform larvae shed in human feces, which reproduce to form infective, skin-penetrating filariform larvae in the external environment. Humans infected with present with varying degrees of clinical manifestations ranging from asymptomatic carriers to acute strongyloidiasis and disseminated infections. Strongyloidiasis is the term used to indicate infection by . It differs from other helminth infections by its ability to cause overwhelming hyperinfection in immunocompromised individuals. Strongyloides infection can last the host's lifetime due to its autoinfection life cycle and cause a wide spectrum of diseases ranging from asymptomatic eosinophilia to severe, life-threatening disseminated disease in immunocompromised patients.
粪类圆线虫，通常被称为蛲虫，是一种通过土壤传播的人体寄生虫，属于线虫类的蛔虫。尽管除了极北和极南地区外几乎在全球都很普遍，但由于流行地区缺乏精确数据，这种寄生虫感染的全球负担仍被低估。因此，粪类圆线虫病成为“被忽视的热带病”（NTDs）中最被忽视的寄生虫感染之一。这种蠕虫主要感染人类，但也自然存在于家犬、猫和灵长类动物中。它在其他人体线虫中独特的特征是能够从人类粪便中排出的杆状幼虫产生自由生活的蠕虫后代，这些后代在外部环境中繁殖形成具有感染性、可穿透皮肤的丝状幼虫。感染粪类圆线虫的人会出现从无症状携带者到急性粪类圆线虫病和播散性感染等不同程度的临床表现。粪类圆线虫病是指由粪类圆线虫感染引起的疾病。它与其他蠕虫感染不同之处在于其能够在免疫功能低下的个体中导致严重的高度感染。由于其自身感染的生命周期，粪类圆线虫感染可以持续宿主一生，并在免疫功能低下的患者中引起从无症状嗜酸性粒细胞增多到严重的、危及生命的播散性疾病等广泛的疾病。
