For perhaps the first time in his mayoralty, Bill de Blasio looked like a man who was in charge Friday. At an hourlong news conference, he was crisp, informed, certain and focused -- which is good -- because at the moment, he's staring into the jaws of a devilish crisis called Ebola.

The mayor's first task is to work with the U.S. Centers for Disease Control and Prevention to make sure the West Africa epidemic doesn't trigger a mass outbreak in New York -- one of the world's busiest and most porous cities, where people and their pathogens breeze through in a continual whirlwind.

That's why de Blasio had the health department's disease detectives out Friday morning, tracing the recent contacts of Craig Spencer, the physician from Doctors Without Borders who Thursday night became the city's first official Ebola case. And that's why other workers were busy Friday -- hauling possible biohazards out of Spencer's Harlem apartment and scrubbing the place down.

The city was doing some hard-nosed medical policing.

But at the same time it was working a gentler angle -- trying to convince anyone who's been to Liberia or Guinea or Sierra Leone in the last 21 days and may be feeling a little feverish to see a doctor -- stat. No one will demand to see your documentation, de Blasio promised. And no one will dun you for insane medical bills when your treatment is over.

New York just wants to see how you're doing and maybe take a look at your temperature.

And if you should have Ebola, the mayor seemed to be saying, we'll help you fight it with everything we've got.

It was a classic public health message -- simultaneously humanitarian and practical -- and as the contagion widens in West Africa, all of us should hope it resonates here.

Oh, and by the way, de Blasio added, forget about that nasty mess in Dallas -- where one man died of Ebola and others were infected. We're learned a lot since then. And in any case, this is New York and we know what we're doing.

It's the right approach. Let's hope it gets us where we want to go.