Thankfully, no. Not in the sneeze and catch it sense. It is, however, possible for two people to be poisoned around about the same time if they're exposed to the same poison. Like drinking from a contaminated well. One person might get sick first, but the other might catch the same thing. There's no vector, though. Just direct poisoning.

I don't imagine MN poisoning would be contagious if it's to do with what's in the blood. Not unless we were doing transfusions between people. [And that has its own set of problems. But talking of blood...]

Listen, Beckett, Angel did just contact me asking about how much blood someone could safely lose in a day. You tell me you've just broken away from her and Rhys... I remember the look you had when I was having that nosebleed. It's getting worse, isn't it?