Martin Salia's friends in Sierra Leone celebrated when the doctor's Ebola test came back negative. But that celebration—in which friends hugged Salia—may have spread the disease to them, and Salia's belief in the negative finding may have cost him his life.

The test result, it turned out a few days later, was wrong. Salia died Monday at Nebraska Medical Center, in Omaha, after a desperate attempt to save his life.

His death shows the limitations of current Ebola testing, which takes time, money, electricity, and effort that is not practical in West Africa, where the needs are extraordinary and the infrastructure poor.

"What we want more than anything is a rapid diagnostic test to tell us if someone has Ebola right away,