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Strongyloides stercoralis
From WikEM
Contents
Background
- Intestinal nematode; roundworm
- Endemic in tropical/subtropical areas such as Africa, Southeast Asia, Central/South America[1]
Life Cycle
- Present in contaminated soil → larvae penetrate skin of hosts walking barefoot → enter venous circulation, migrate to lungs, then are expectorated to pharynx and swallowed → larvae develop into females that lay eggs asexually into GI tract, which hatch into larvae and are excreted into stool
- Larvae either become sexually reproducing males/females or filariform larvae that can reinfect host
- Autoinfection: Unique to Strongyloides; GI larvae can migrate from GI tract to venous system, then to lungs and proceed with life cycle
- Can lead to dramatic increase in worm burden and hyperinfection in immunocompromised
Risk factors
- Corticosteroid use, immunosuppression
- Transplantation
- Hematologic neoplasm
- Human T-lymphotropic virus-1 infection (HTLV-1)
- Malnutrition
- Diabetes
- Chronic renal failure
- Chronic alcohol use
Clinical significance
- Chronic infection in immunosuppressed can lead to fulminant dissemination with case fatality rate as high as 70%; strong index of suspicion is needed in such cases
Clinical Features
- Asymptomatic in up to 60% of those infected[2]
- Nonspecific GI complaints are most common presentation
- Weight loss, diarrhea, abdominal pain, vomiting
Dermatologic
- Larva currens: rapidly progressive pruritic linear eruption due to migration of larvae
- Perianal pruritus
- Foot pruritus (“ground itch”)
Respiratory
- Dry cough
- Wheezing
- Loeffler’s-like syndrome: fever, shortness of breath, wheezing, pulmonary infiltrates
Immunocompromised patients
- Respiratory and systemic symptoms such as fever will be more common[3]
- Disseminated disease will invade multiple organ systems, including liver and brain
Differential Diagnosis
- Inflammatory bowel disease
- Schistosomiasis
- Filariasis
- Hookworm
- Toxocara canis
- Atopic dermatitis
- Asthma
- Allergic bronchopulmonary aspergillosis
- Coccidioidomycosis
- HIV
- Churg-Strauss syndrome
- Eosinophilic leukemia]
Evaluation
- Establish possibility of infection (travel to endemic areas, etc)
- Uncomplicated strongyloidiasis: 3 serial stool samples screened for ova and parasites, as well as ELISA for Strongyloides
- Complicated strongyloidiasis: blood/sputum cultures, in addition to above
- Notable eosinophilia in up to 70% of cases, though can be absent in immunosuppressed
- Gram negative bacteremia may be present in immunocompromised
Management
Uncomplicated strongyloidiasis, normal immune system
- Ivermectin 200 mcg/kg daily x 1-2d (drug of choice)
OR
- Albendazole 400mg BID x 7d
- Can consider albendazole prophylaxis in immigrants from endemic regions with consistent clinical presentation
Immunosuppressed
- Combination therapy: albendazole 400mg BID x 7d AND ivermectin 200 mcg/kg daily x 1-2d[4]
- Antibiotics may need to be continued until there is evidence that parasite is cleared[4]
Disposition
- Discharge uncomplicated cases in those who are not immunosuppressed
- Admit if immunocompromised or systemic symptoms
References
- ↑ Buonfrate D, Requena-Mendez A, Angheben A, Munoz J, Gobi F, Van Den Ende J, Bisoffi Z. Severe strongyloidiasis: a systematic review of case reports. BMC Infectious Diseases 2013, 13: 78. doi:10.1186/1471-2334-13-78
- ↑ Greaves D, Coggle S, Pollar C, Aliyu SH, Moore EM. Strongyloides stercoralis infection. BMJ 2013;347:f4610 doi: 10.1136/bmj.f4610 (Published 30 July 2013).
- ↑ Lim S, Katz K, Krajden S, Fuksa M, Keystone JS, Kain KC. Complicated and fatal Strongyloides infection in Canadians: risk factors, diagnosis and management. CMAJ 2004; 171 (5): 479-484.
- ↑ 4.0 4.1 Feely NM, Waghorn DJ, Dexter T, Gallen I, Chiodini. Strongyloides stercoralis hyperinfection: difficulties in diagnosis and treatment. Anaesthesia 2010; 65: 298-301.
