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Strongyloidiasis is a human parasitic disease caused by the nematode (roundworm) Strongyloides stercoralis. Other Strongyloides include S. fülleborni, which infects chimpanzees and baboons and may produce limited infections in humans.
Additional recommended knowledge
The Strongyloides' life cycle is more complex than that of most nematodes with its alternation between free-living and parasitic cycles, and its potential for autoinfection and multiplication within the host. Two types of cycles exist:
Tropical and subtropical areas, but cases also occur in temperate areas (including the South of the United States). More frequently found in rural areas, institutional settings, and lower socio-economic groups.
Frequently asymptomatic. Gastrointestinal system symptoms include abdominal pain and diarrhea. Pulmonary symptoms (including Löffler's syndrome) can occur during pulmonary migration of the filariform larvae. Dermatologic manifestations include urticarial rashes in the buttocks and waist areas. Blood eosinophilia is generally present.
Strongyloidiasis can become chronic and then become completely asymptomatic.
Disseminated strongyloidiasis occurs when patients with chronic strongyloidiasis become immunosuppressed. It presents with abdominal pain, distension, shock, pulmonary and neurologic complications and septicemia, and is potentially fatal. Eosinophilia is often present but is sometimes absent.
Dissemination can occur many decades after the initial infection and has been associated with high dose corticosteroids, organ transplant, HIV, lepromatous leprosy, tertiary syphilis, aplastic anemia, malnutrition, advanced tuberculosis and radiation poisoning. It is often recommended that patients being started on immunosuppression be screened for chronic strongyloidiasis; however, this is often impractical (screen tests are often unavailable) and in developed countries, the prevalence of chronic strongyloidiasis is very small, so screening is usually not cost-effective, except in endemic areas.
Diagnosis rests on the microscopic identification of larvae (rhabditiform and occasionally filariform) in the stool or duodenal fluid. Examination of serial samples may be necessary, and not always sufficient, because direct stool examination is relatively insensitive.
The stool can be examined in wet mounts:
Culture techniques are the most sensitive, but are not routinely available in the West. Direct examination must be done on stool that is freshly collected and not allowed to cool down, because hookworm eggs hatch on cooling and the larvae are very difficult to distinguish from strongyloides.
The duodenal fluid can be examined using techniques such as the Enterotest string or duodenal aspiration. Larvae may be detected in sputum from patients with disseminated strongyloidiasis.
The drug of choice for the treatment of uncomplicated strongyloidiasis is ivermectin. Other drugs that are effective are albendazole and thiabendazole (25 mg/kg twice daily for 5 days). All patients who are at risk of disseminated strongyloidiasis should be treated. It is not clear what the optimal duration of treatment for patients with disseminated infectious should be.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Strongyloidiasis". A list of authors is available in Wikipedia.|