Strongyloides stercoralis infection as a manifestation of immune restoration syndrome?

Strongyloides stercoralis infection in the immunocompromised host

Strongyloides stercoralis is an intestinal nematode acquired in the tropics or subtropics. Most often, it causes chronic, asymptomatic infection, but a change in immune status can increase parasite numbers, leading to hyperinfection syndrome, dissemination, and death if unrecognized. Corticosteroid use is most commonly associated with hyperinfection syndrome. Diagnosis of Strongyloides infection is based on serology and serial stool examinations for larvae. The treatment of choice for chronic, asymptomatic infection is oral ivermectin. Alternative pharmacologic agents include albendazole and thiabendazole. For hyperinfection syndrome, ivermectin remains the drug of choice, though therapy duration must be individualized with the end point being complete parasite eradication. Recurrent strongyloidiasis should prompt an evaluation for human T-cell lymphotropic virus type 1 coinfection. No test of cure is currently available, although immunoglobulin G antibody levels have been shown to decline within 6 months of successful treatment.

Immune reconstitution disease: recent developments and implications for antiretroviral treatment in resource-limited settings

PURPOSE OF REVIEW

We review literature published over the past 2 years regarding the immunopathogenesis, epidemiology, clinical spectrum and outcomes of immune reconstitution disease in patients receiving antiretroviral treatment. Particular attention is drawn to data relevant to resource-limited settings.

RECENT FINDINGS

In high-income countries, immune reconstitution disease occurs in association with a largely predictable spectrum of pathogens, including the herpesviruses, Mycobacterium tuberculosis and Mycobacterium avium complex, Cryptococcus neoformans and hepatitis viruses. Dermatological manifestations are most frequent. In resource-limited settings, patients accessing antiretroviral treatment programmes typically have advanced immunodeficiency, which increases risk of immune reconstitution disease. M. tuberculosis and C. neoformans have emerged as the key causes of morbidity and mortality associated with immune reconstitution disease. An increasing number of 'tropical' infections, including leprosy, schistosomiasis, strongyloidiasis, leishmaniasis, histoplasmosis and many nontuberculous mycobacteria, are also now recognised to provoke immune reconstitution disease but the overall spectrum and relative importance of these organisms remain to be defined. Better characterisation of immune reconstitution disease in these settings is needed to enable development of guidelines regarding prevention, diagnosis and management.

SUMMARY

While immune reconstitution disease in high-income countries has been clinically and epidemiologically well described, much remains to be learned in resource-limited settings in which immune reconstitution disease is emerging as a significant cause of morbidity and mortality.

Manifestations, diagnosis, and treatment of Strongyloides stercoralis infection

OBJECTIVE

To summarize current literature on the manifestations, diagnosis, and treatment of Strongyloides stercoralis infection.

DATA SOURCES

A search was conducted of PubMed (1970-August 2007). Search terms included Strongyloides stercoralis, hyperinfection, prevention, and treatment. Reviews, studies, and recent case reports were included. Additional references were obtained from article bibliographies.

STUDY SELECTION AND DATA EXTRACTION

All studies or review articles published in English from 1970 to August 2007 and case reports of hyperinfection or disseminated disease published since 2000 were evaluated.

DATA SYNTHESIS

Strongyloidiasis is a parasitic infection endemic to tropical, subtropical, and temperate areas including the Appalachian region of the southern US. Prevalence rates vary widely. Patients may present with infection decades after original exposure. Diagnosis can be achieved by identifying the larvae in the stool; usually, more than one sample is needed. Most patients are asymptomatic. However, in immunosuppressed patients, a hyperinfection syndrome or disseminated disease may occur due to the ability of the parasite to reproduce within the host. The most common risk factors for these complications are immunosuppression caused by corticosteroids and infection with human T lymphotropic virus type 1. Treatment options for uncomplicated disease include thiabendazole, ivermectin, and albendazole. Thiabendazole has been replaced by ivermectin as treatment of choice due to better tolerance. These antihelminthics have been used to treat hyperinfection or disseminated disease alone or in combination, but data are limited to case reports or case series. Prevention of disease is mainly achieved by wearing shoes in endemic areas to avoid contact with infected soil.

CONCLUSIONS

Strongyloides is a unique parasite that can cause a hyperinfection syndrome and disseminated infection several years after exposure. Treatment options include ivermectin, thiabendazole, or albendazole. Information on the best treatment for disseminated disease and hyperinfection is limited.