Parasitic infections are, generally speaking, not a nice experience. On the whole, sexually transmitted infections (STIs) are not a walk in the park either. But it’s a little-known fact that these two unpleasantries of life sometimes come hand in hand creating a double whammy of dreadfulness.

A new medical case study, published in BMJ Case Reports, tells the story of a man who managed to contract Entamoeba histolytica, a nasty poop-dwelling parasite, through having sex with his wife.

The case first came to light when the 67-year-old man was admitted to a hospital in the French city of Dijon with pain in his liver and a fever. He also reported some unpleasant stomach issues over the previous six months that hadn’t responded to the medication prescribed by his doctor. A later poop sample tested positive for E. histolytica.

E. histolytica lives in the poop of humans and other primates. While this means it typically hangs out in the intestinal tract, it can also enter the bloodstream and find its way to the liver, brain, and other organs. Most people contract the parasite by drinking dirty water or eating food that’s come into contact with poop.

The curious life of E. histolytica. CDC

Curiously, the doctors noted that their patient had never traveled outside Europe. This caught their attention because E. histolytica is typically found in tropical countries with poor sanitary conditions, especially in rural areas. His wife, however, had traveled extensively to South America, India, Burma, Vietnam, and Laos. It also became clear that she had previously had a sexual relationship with a man who was diagnosed with intestinal amoebiasis, although she never experienced any symptoms.

Based on these circumstances, the doctors concluded that the parasite was sexually transmitted to the man from his wife.

It’s unclear why the doctors ruled out other methods of transmission, such as the woman not washing her hands properly after using the bathroom. Sex between men is known to be a risk factor for contracting the parasite, as are “anal-to-oral sexual practices”, however, the case report notes that “very few heterosexually transmitted cases have been reported.” The report doesn’t specify exactly how the parasite was transmitted, it simply notes the man was infected “through heterosexual intercourse with his healthy French female partner who was a carrier of the parasite.” It's possible the parasite leached into the woman's bloodstream and was transmitted during sex or, arguably the more likely scenario, it was passed through the anal-to-oral route.

Whatever this pair got up to in the bedroom, they were both treated with the drugs metronidazole and tiliquinol-tilbroquinol, resulting in the man’s symptoms lifting within just 48 hours. Two months later, both tested negative for E. histolytica and were seemingly healthy. All’s well that ends well, we guess.