CDC director Thomas Frieden said that health-care workers were not under active Ebola observation like the Dallas civilians who may have been exposed, but were instead “self monitoring” for symptoms. They were not supposed to travel on public transportation or commercial flights. Nor could he explain the new cases of transmission except as an unspecified “breach of protocol,” perhaps when they removed hazmat suits.

The new victim was not vomiting or bleeding in the air (how reassuring) and thus was unlikely contagious. Yet the CDC claims the Dallas Ebola burst—while still minor—is under control except when it isn’t. It would be easier to trust the official appeals for calm if officials did not keep supplying reasons to believe otherwise, or behaving as if it is absurd to fear a pathogen that liquefies internal organs.

An Ebola outbreak on the Eastern seaboard or some other densely populated region could well cost billions of dollars to contain and perhaps throw the economy into recession, akin to the 2009 SARS pandemic in China. The possibility is very remote, and Washington is marginally more accountable than Beijing. Then again, the CDC said domestic cases were improbable too.