Please ask your brother to confirm that with the hematologist, and if the hematologist does confirm it, ask him to identify the microbe that causes TTP and provide any other evidence to that effect. There are substantial indications that at least some cases of TTP are caused by bacteria, but this is the first I've heard that it might be transmissible from human to human. There was one case in the literature from a long time ago about a husband-wife couple who both got TTP, which did spark questions about whether it was contagious, but there have been very few known instances of that. On the other hand, there are known cases of familial TTP, in which brothers/sisters/children/parents are known to come down with it. However, this kind of TTP behaves differently from the so-called "idiopathic" cases of TTP -- i.e., people with no known family history and no known risk factors such as stents, HIV+ status, certain prescription drugs etc. Moreover, there is nothing to be ashamed at in being afraid of catching TTP. Rest assured, though, that if human-human transmission does occur, it's pretty rare. No one in my family came down with it other than me, and that probably holds for the other posters on this board. As I said, there's very little in the scientific literature on that. Prayers for yr brother. Ilona.