(May 23, 2019 at 2:32 am)onlinebiker Wrote: If two races that evolved on different planets met - wouldn't simple contact likely be fatal for both sides due to bacterial and viral contamination?
Not really. Even on Earth do pathogens rarely jump from one species to another because bacteria and viruses evolve alongside their hosts. Although all human diseases seem to have come from animals.
But in Star Trek alien species are so close genetically that they can even mate, so yeah pathogens would be a problem and they do sometimes get them like in "Tuvix" episode but usually they get filtered during teleportation. In prequel show "Enterprise" they didn't have teleportation yet so everyone had to go to some sort of isolation tank to make sure they got cleaned of pathogens.