Strongyloidiasis
Strongyloides stercoralis is a soil-transmitted nematode uniquely capable of autoinfection, so it can persist for decades and, in a host started on glucocorticoids or otherwise immunosuppressed, progress to hyperinfection with gram-negative bacteremia; diagnosis is by stool larvae or serology and treatment is ivermectin.
- Topic reviewThe full article, organized the way the exam asks it.
- ABIM-format MCQsVignettes with an explanation for every wrong answer.
- Key factsThe numbers and thresholds worth memorizing, up front.
- AI tutorMedBrain answers the question you're stuck on.
What this article covers
- Overview
A soil-transmitted nematode unique among intestinal helminths because it can complete its life cycle inside the human host: Strongyloides larvae can mature and reinvade the host from within the gut…
- Epidemiology
Endemic in warm, moist climates worldwide, including the southeastern United States: most US cases occur in the southeastern states or in travelers and immigrants from endemic tropical and subtropical regions.
- Risk factors
Corticosteroid therapy is the single most important precipitant of hyperinfection: even short courses of systemic glucocorticoids can convert chronic, low-level autoinfection into accelerated larval proliferation and dissemination.
- Pathophysiology
Filariform larvae in contaminated soil penetrate intact skin, usually of the feet: this is the initial route of infection, producing the itchy lesions at the site of entry.
- Clinical features
Larva currens: pruritic, migratory, serpiginous lesions, often on the feet, buttocks, or trunk: this is the earliest and most specific finding, corresponding to the itchy lesions at the site of…
- Differential diagnosis
Hookworm (Ancylostoma duodenale, Necator americanus): also enters through the skin and causes pulmonary migration, but produces iron deficiency anemia from chronic intestinal blood loss rather than…
- Diagnosis
The diagnosis is confirmed by identifying Strongyloides larvae (not eggs, as with other intestinal nematodes) on direct stool examination, or by a positive Strongyloides serology; there is no formal…
- Management
First, confirm the diagnosis (stool larvae or serology) before treating, except when hyperinfection is suspected in a critically ill patient, in which case treatment should begin empirically while confirmatory testing is pending.
- Complications
Gram-negative bacteremia and sepsis from bowel-wall breach during hyperinfection: migrating larvae carry enteric flora into the bloodstream, a leading cause of death in hyperinfection.
- Prognosis
Uncomplicated strongyloidiasis has an excellent prognosis with ivermectin: most patients clear the infection with the standard 2-day course and remain asymptomatic thereafter.
- Prevention
Screen any patient with residence in or travel to an endemic area (the southeastern United States, Latin America, Southeast Asia, or sub-Saharan Africa) with stool exam and/or serology before…
Read the whole article
Subscribing to Internal Medicine opens every article, the full question bank and MedBrain, on the web, iPhone and Android.
Related articles
- Ascariasis (roundworm infection)
Ascariasis is fecal-oral infection with Ascaris lumbricoides, the largest intestinal nematode, treated with albendazole 400 mg single dose; it causes Loffler pulmonary eosinophilia during larval lung migration and, with heavy adult worm burden, intestinal, biliary, or pancreatic duct obstruction.
- Toxocariasis
Toxocariasis is human infection with the dog or cat roundworm Toxocara canis or Toxocara cati, acquired by ingesting embryonated eggs, producing visceral larva migrans with hepatic, pulmonary, and eosinophilic disease or ocular larva migrans mimicking retinoblastoma. Diagnosis rests on compatible exposure and clinical findings plus Toxocara-specific serology, and treatment combines an antihelminthic with corticosteroids for organ-threatening inflammation.
- Schistosomiasis
Schistosomiasis is a trematode infection acquired by cercarial penetration of skin during freshwater contact, causing intestinal and hepatosplenic disease with Schistosoma mansoni or S. japonicum, or urinary tract disease with S. haematobium. Diagnosis rests on demonstrating eggs in stool or urine or a positive serology, and praziquantel is the treatment for every species.
- Trichinellosis
Trichinellosis is infection with Trichinella spiralis larvae acquired from undercooked meat, especially pork or wild game, producing an initial intestinal illness followed by larval encystment in striated muscle causing myositis, periorbital edema, and eosinophilia. Diagnosis rests on eosinophilia and elevated creatine kinase confirmed by serology or muscle biopsy, and treatment combines an antihelminthic with corticosteroids for severe systemic disease.