If hiv positive blood was on a surface, could someone get infected if they touched it with an open wound? how long does hiv live for outside the body?

Yes: But this would be extremely rare. Hiv will not survive long outside the body, but might if the blood has not yet dried up entirely. Why in heavens name would anybody touch somebody's blood on a surface with their own open wound? A very improbable scenario. But the answer to your question is that this is possible.

Wimpy Virus: It is important to remember that viruses like hepc, HIV and others are strings of proteins connected by very weak bonds. They require many things to be active and need living cells to reproduce and survive. Transfer/infection occurs when anything open or a mucous membrane (anus, vagina, mouth) contacts an organic substance (blood, semen) that has the virus. The key is to avoid, not touch !

Dr Raff agreed