The Ebola outbreak that emerged in March in West Africa has killed more than half the 1,300-plus people who have been infected, making it the deadliest outbreak ever. For now, only symptoms can be treated in hopes of keeping people strong enough that their immune systems can catch up. But in the past five years, several experimental vaccines and treatments have been effective in other primates, said virologist Alexander Bukreyev of UTMB, and he estimates that something could be approved for human use within five years.