Originally Answered: herpes/STDS/immune-system suppressed help?
I don't believe that genital herpes can be fatal in immuneosuppressed people. However, while healthy adults can have little or no symptoms during herpes outbreaks, immuneosuppresed people can suffer from longer, more painful outbreaks.
Herpes can be particularly dangerous in cases of pregnancy, and can be fatal to the baby, or an ocular infection of herpes can cause blindness. That's really, really uncommon, though. (Ocular.)
Remember, though, that herpes is spread even without open sores or other symptoms, and it is a very good idea to take an antiviral drug such as Acyclovir. (Or one of the other cyclovirs.)