Factors associated with the sexual transmission of Strongyloides stercoralis in men who have sex with men: A systematic review.

Strongyloides stercoralis is a parasitic worm with a complex life cycle and can cause significant morbidity, including a proctocolitis and life-threatening hyperinfection syndrome. Limited reports from non-endemic areas, including in men who have sex with men (MSM), suggest sexual transmission of S. stercoralis. In this systematic review of the published literature, we aimed to explore the associated factors of S. stercoralis in MSM. We systematically searched three bibliographical databases (MEDLINE, CINAHL and EMBASE) up to November 2022. We used a two-stage process to assess eligibility: the primary author conducted an initial screen of abstracts, and then three authors conducted independent full manuscripts to determine the final eligible manuscripts. We only included manuscripts written in English that contained data on specific factors associated with sexual transmission in MSM. We used the STROBE checklist to assess the risk of bias and synthesized the narrative data using the SWiM method. Seven manuscripts were eligible for this review (four case reports, one case series, one cross-sectional study and one experimental study), which included 22 individuals from Europe and the Americas. From these studies, S. stercoralis in MSM was associated with living with HIV (including having a low CD4 count and not using antiretrovirals), having a concomitant sexually transmitted infection (Chlamydia trachomatis, Neisseria gonorrhoeae, Treponema pallidum and hepatitis C) and a concomitant (sexually transmitted) protozoal infection (Entamoeba histolytica, Giardia lamblia), travel to the S. stercoralis endemic area, multiple sexual partners from endemic areas, oro-anal sexual contact and chemsex. Although limited by the number of cases in the literature, we have highlighted some possible biological and behavioural risk factors associated with the sexual transmission of S. stercoralis in MSM that could be used to both target future research and S. stercoralis public health control interventions.