Weird Links

 http://www.guardian.co.uk/science/2007/sep/25/spac...

Food poisoning bacteria become super-virulent in space, according to a study of salmonella that spent 12 days orbiting the Earth on the space shuttle Atlantis.

It is the first study to examine the effect of space flight on the virulence of a pathogen. "Given the proposed increase in both duration and distance from Earth for future manned space flight missions - including lunar colonisation and a mission to Mars - the risk for in-flight infectious diseases will be increased," said Cheryl Nickerson at Arizona State University.

So I jumped onto pubmed and found a couple of other papers on this topic also by Nickerson:

Microgravity as a novel environmental signal affecting Salmonella enterica serovar Typhimurium virulence Infect Immun. 2000 Jun;68(6):3147-52.

Low-Shear modeled microgravity alters the Salmonella enterica serovar typhimurium stress response in an RpoS-independent manner. Appl Environ Microbiol. 2002 Nov;68(11):5408-16.

It looks like what they're saying is that low-gravity induces a stress response via the global regulator, RpoS. Upregulation of virulence factors can occur in response to stress; whereby the whole point of "virulence" is to increase the chances of survival in a hostile environment, rather than just to make you sick