Ebola replicates very quickly, before most people’s bodies can mount an attack. People often have massive bleeding seven to 10 days after infection. It effectively disables the immune system by hampering the development of antibodies and T cells that would target the virus. Scientists are not certain exactly how. What can be done? For now, only symptoms can be treated in hopes of keeping people strong enough that their immune systems can catch up. But within 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 the next five years.