Worldwide prevalence of SI may be as high as 100 million people, with an increasing number seen in developed countries among immigrants (including those from Latin America), refugees, and travelers. “Autoinfection” by Strongyloides allows it to complete its life cycle between the GI tract and the lung without leaving the host, and is often associated with chronic asymptomatic infection in the immunocompetent persons¹.

Immunocompromised patients, however, particularly those treated with corticosteroids (including systemic courses as short as 6 days, or local injection)  are at increased risk of developing an accelerated form of autoinfection due to SI, also known as  hyperinfection syndrome (HIS)^1,2.  HIS has been reported as late as 64 years after leaving an endemic  area!¹.   When Strongyloides larvae disseminate away from the lung or GI tract into other organs (e.g. brain) the mortality rate may approach 100%, if untreated.

Due to the potential complications associated with untreated SI, particularly in the immunocompromised , routine screening of anyone with a potential Strongyloides-exposure history (irrespective of symptoms or years since exposure) has been advocated^1,3.  In our patient with COPD, screening for asymptomatic SI by a highly sensitive test (eg serology) should be considered (as early as possible if corticosteroids are being considered for treatment of his COPD).  Some have also advocated empiric treatment with ivermectin in “at risk patients” in whom testing is not feasible or practical^1,4.

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References

1. Mejia R, Nutman TB. Screening, prevention, and treatment for hyperinfection syndrome and disseminated infections caused by Strongyloides stercoralis. Curr Opin Infect Dis 2012;25:458-463.
2. Keiser PB, Nutman TB. Strongyloides stercoralis in the immunocompromised population. Clin Microbiol Rev 2004;17:208-217.
3. CDC. Strongyloides. http://www.cdc.gov/parsites/strongyloides/helath_professionals/ , accessed September 20, 2016.
4. Santiago M, Leitão B. Prevention of strongyloides hyperinfection syndrome: a rheumatologic point of view. Eur J Intern Med 2009;20:744-748.

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