Objective Giardia duodenalis causes enteritis and malabsorption and can be sexually transmissible in men who have sex with men (MSM). The aim of this study was to explore factors associated with MSM with G. duodenalis.

Methods MEDLINE, Embase, Emcare, PubMed, Global Health and Web of Science were searched for manuscripts published up to February 2024. The primary author screened manuscript titles and abstracts; two authors independently reviewed full-text manuscripts for eligibility and risk of bias. We only included manuscripts that included MSM with G. duodenalis and explored at least one risk factor or association. Narrative data were synthesised following the population of a predetermined table.

Results Twelve manuscripts were included in this review, including cross-sectional studies (n=7), case series (n=3), cohort study (n=1), case-control study (n=1), from the USA (n=8), the UK (n=1), Cuba (n=1), Spain (n=1) and Canada (n=1) published between 1977 and 2024 and included 191 MSM with G. duodenalis. This review highlighted demographic (living with HIV and living with HIV with a CD4 count <400 cells/mL), biological (coinfection with Neisseria gonorrhoeae, Chlamydia trachomatis, Escherichia coli, Entamoeba histolytica, non-pathogenic enteric parasites, intestinal spirochaetosis, Enterobius vermicularis, previous Treponema pallidum, N. gonorrhoeae, Shigella spp, hepatitis A, E. histolytica and G. duodenalis) and behavioural (lack of anal douching, oral-anal sex, oral sex, anal sex, group sex, use of sex toys, having more than one sexual partner per week, non-condom use, being part of a sexual network or having a sexual partner with G. duodenalis) factors associated with MSM with G. duodenalis.

Conclusion This review has highlighted some demographic, behavioural and biological factors associated with MSM with G. duodenalis, which provide insight for public health control strategies and future research.