Sexual transmission of giardiasis: a neglected route of spread?

Sexually transmitted infections (STIs) are often discussed in the context of syphilis, gonorrhea, herpes, chlamydiasis and AIDS. However, since the past 30 years of the last century, epidemiology and natural history studies have led to improved understanding of giardiasis as a STI, as a result of oral-anal sexual contact. Studies suggest that Giardia is an increasingly recognized infection that may be underdiagnosed under the STI context. Health care providers should maintain a high index of suspicion for Giardia, obtain suitable diagnostic tests to identify and screen those at high risk for this infection, institute appropriate therapy, counsel patients regarding treatment compliance, follow-up, encourage partner notification and teach strategies for preventing the transmission of this disease, including the discussion of the risk of enteric infections after oral-anal sexual contact. We summarize some data concerning the research and clinical literature on Giardia infection as a STI and identify the specific recommendations for control of giardiasis as STI that available evidence indicates can reduce its transmission.