In an ideal world, health care workers returning from West Africa would get a quick blood test to prove they aren't carrying the Ebola virus. A test like that would likely put to rest some of the anxiety surrounding these doctors, nurses and scientists.
Unfortunately, even the best blood test in the world can't do that.
The test uses a technology called PCR, for polymerase chain reaction. It can detect extraordinarily small traces of genetic material from the Ebola virus.