The virus rapidly reproduces, infecting multiple kinds of cells before the immune system recognizes the threat and starts to fight back. There is no specific treatment for Ebola but specialists say basic supportive care — providing intravenous fluids and nutrients, and maintaining blood pressure — is crucial to give the body time to fight off the virus. Worse, in the most severe cases, patients' blood vessels start to leak, causing blood pressure to drop to dangerous levels and fluid to build up in the lungs. Doctors at Emory and Nebraska Medical Center, which successfully treated another aid worker and now is treating a video journalist infected in West Africa, say there's no way to know if those treatment really helped. Options include a plasma transfusion, donated by Ebola survivors who have antibodies in their blood able to fight Ebola, or a handful of experimental drugs that are in short supply.