SpaceflightMemes

Yeah, I just saw an article about it, I'll dig it up, I think it was on universetoday. Doctors are trying to figure out why healthy astronauts have certain health issues, during an extended stay in space. One THEORY is that the bacterial/fungal environment on the ISS is unnaturally restricted, the personnel spend hours a day just cleaning, so the "bad" bacteria and viruses may lack competition there, which leads to infections that would resolve faster on Earth, all other things being equal. The viruses and bacteria may also mutate into meaner versions in the ISS, needs much more study.

TLDR: everything is too clean on the ISS, introduce some carefully selected dirt!