A urinary tract infection can cause infertility, so maybe that.
But this presumes that we should reinterpret the gemara in a kvetched way in order to make it work out; or that, even if the medical descriptions in the gemara are scientifically incorrect, there must be some parallel in which what they are saying is effectively true.
I don't know that I agree with either of those two underlying assumptions. For more on this topic, see here. Also, here:
A reader directed me to this interesting journal entry of an avreich in a kollel of which Rav Moshe Shapiro is the nasi. The kollel was studying the Gemara which speaks of there being two channels in the male genital organ, one for urine and one for semen (whereas in fact there is only one channel). Chazon Ish responded by claiming that nishtaneh hateva, people have evolved. Rav Moshe Shapiro disputed this and also vehemently objected to the notion that any Torah scholar could ever have been mistaken about the physical reality. Instead, he adopted a Maharal-style approach (though the Maharal never, to my knowledge, explicitly applied his approach to halachic topics) in which the Gemara is talking about the metaphysical reality.
This radical approach took the kollel by surprise. The Rosh Kollel apparently realized the astounding ramifications of such an approach - בסופו של הדיון אמר ראש הכולל שהוא חש אבוד ונבוך בשאלות המעשיות הנובעות מהגישה של רבי משה ואינו יודע כיצד להתקדם. After all, if one refuses to acknowledge that Chazal possessed incomplete knowledge of the natural world, and one refuses to say nishtaneh hateva, then what does one do with, for example, the Gemara which says that one can violate Shabbos to save the life of a fetus born after seven months, but not one born after eight months?