The above image is an electron micrograph of cholera - which as far as I know, has never been to space.  But humanity has now crossed a new frontier and sent a virus into space - and it came back 3X more deadly!

NASA sent some salmonella into space (very carefully wrapped) and a similar sample as a control.  The result: the space-salmonella killed 90% of mice after 25 days (vs. 60% for the control) and it took 1/3 as much of the virus.  No one knows why, but it's suspected to have something to do with the lack of gravity.

Let's speculate about what this could mean (of course, none of the following is going to occur, but it's fun to let your imagination run wild every now and then):

Iran and the Great Speculator decide to abandon their nuclear arms quest and instead focus on creating missiles that carry microbes into space and then let their cargo "mature" before crashing into Israel/America.  The U.S. is bankrupted trying to create a missile shield that can stop anything from crashing on U.S. terra firma.

Pharaceutical companies realize that it's cheaper to send microbes into space than finance traditional R&D - spurring private space research and a private international space station.

China starts sending soldiers into space and exposes them to microbes; they then launch a chemical attack against Taiwan.  No one can come to Taiwan's aide as only Chinese soldiers are immune to the disease.  However, it all backfires as the soldiers can't return to their families (they're too exposed to the disease), so a young PLA colonel revolts and starts a new independent Taiwan - and the mainland can't invade as the land is too poisonous to inhabit.