According to NASA researchers, humans in orbit experience changes in their auto-immune reactions. Apparently T-cells, the immune system's soldiers, do not behave in orbit as they do on Earth, with the consequence of apparent reductions in their effectiveness.

For example, the article notes, Sneeze aerosols of astronauts contain up to 10x the number of epstein-barr viruses thought to be responsible for infectous mononucleosis

Article

I know that some astro/cosmonauts have complained of persistent sinus problems during their time in space, but I'm not aware of any other orbital maladies of an infectous nature which might be the result of the auto-immune changes noted.

Interesting.

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