stercoralis

Strongyloides stercoralis is a parasitic nematode that infects humans, causing strongyloidiasis. It has a unique autoinfective cycle that can sustain chronic infection for years or decades. Most infections are asymptomatic, but the parasite can produce a range of gastrointestinal, cutaneous, and pulmonary symptoms. In immunocompromised hosts, infection may progress to hyperinfection or disseminated disease with high morbidity and mortality.

Transmission occurs when filariform larvae in contaminated soil penetrate intact skin, typically of the feet. The larvae migrate hematogenously to the lungs, ascend the airways, are swallowed, and mature in the small intestine. In the intestine, parasitic females lay eggs that hatch into rhabditiform larvae. These larvae are either excreted or become infective filariform larvae within the host, enabling autoinfection and persistence without external exposure.

Clinical features vary widely. A characteristic cutaneous sign is a serpiginous, pruritic rash at the entry site, sometimes described as larva currens. Gastrointestinal symptoms include abdominal pain, diarrhea, and malabsorption. Pulmonary involvement can produce cough and wheezing during larval migration. In hyperinfection or disseminated disease, larvae invade multiple organs, and secondary bacterial sepsis may occur, often requiring urgent treatment and carrying a high risk of death if not managed promptly.

Diagnosis relies on detection of larvae in stool or intestinal samples, with methods such as Baermann technique or agar plate culture increasing sensitivity. Serology (antibody tests) supports diagnosis but may cross-react with other helminths; eosinophilia can be present but may be absent in severe cases.

Treatment and prevention: Ivermectin is the first-line therapy; albendazole or thiabendazole are alternatives in some settings. Hyperinfection requires extended or repeated courses and careful management. Preventive measures include wearing shoes in endemic areas, avoiding soil exposure, and screening at-risk individuals before immunosuppressive therapy.