

A girl suspected of being infected with the Ebola has her temperature checked at the government hospital in Kenema, Sierra Leone. (AFP/Carl De Souza/Getty)

Pharmaceutical company Roche announced Monday that the U.S. Food and Drug Administration had provided an Emergency Use Authorization -- a sort of pre-approval for use in particularly bad outbreaks -- for a new kind of Ebola test.

This isn't the first test to get this kind of approval during the 2014 outbreak of the Zaire strain of Ebola, which has killed more than 7,800 people to date and is still an ongoing crisis in parts of West Africa. Although the United States has only seen four cases so far (with one death), concern about the disease remain high. Last week, the Centers for Disease Control and Prevention reported that the agency had mishandled samples of the virus, possibly exposing one worker.

So it's no surprise that Swiss company Roche has put its version of a rapid test forward. The LightMix Ebola Zaire rRT-PCR Test works in about three hours, and is designed for Roche's testing consoles.

Those letters in the test name stand for "real-time reverse transcription polymerase chain reaction." That means the test works by detecting the signs of the Ebola virus on a genetic level.

Here's how the virus spreads and how contact tracing works to stop outbreaks. (Gillian Brockell/The Washington Post)

The test starts by looking for a specific chunk of mRNA, or messenger RNA, which are molecules that carry genetic information from DNA over to the parts of a cell that produce proteins. The test then translates that mRNA strand into the corresponding DNA strand, and uses a process called a polymerase chain reaction to copy the DNA strand millions of times over. Once there's enough DNA to test, the clinician can see whether the original mRNA strand was the right one, and be sure that it's really present in the blood sample.

Several other rRT-PCR tests have also received this kind of emergency approval. The tests are relatively quick at three hours, and since they detect the DNA of the virus they're very accurate.

Why approve multiple tests? The consoles that run these kinds of diagnostics are expensive, so a brand-specific test might not be universally usable by hospitals around the U.S.

The emergency-use designation allows certain laboratories in the country to use the test in response to the current outbreak. The drug has been tested, but not rigorously enough to achieve the FDA's full stamp of approval. Roche will still have to go through those hoops in order for the test to be standard issue at labs and hospitals.

[Related: 7 painful lessons that Ebola taught us]

Unfortunately, adding more in-lab tests probably won't do much to improve Ebola diagnoses. Right now the biggest concern is that many patients are far from labs equipped with these expensive testing apparatuses.

What the CDC is really waiting for is a rapid test that can be carried around and administered by aid workers in the field. If Ebola could be accurately diagnosed with a cheek swab dipped into a vial of testing solution, for example, health-care workers on the scene would be able to act more quickly to contain and treat patients in the early stages of the virus.