People need permission from authority before they stop showing up to work.

"Hey [manager], given my recent trip to Italy, I'm going to WFH for [some period of time], make sure I'm healthy..."

"OK."

I assume your company has travel policies in effect? I mostly work from home anyway but, if I were in an office and traveled to a country that wasn't on my company's self-quarantine list, I'd assume I was expected to go into the office. If your company didn't have Italy on their list (and it maybe should be) that's for your travel department to make decisions on not an individual traveler.

Italy wasn't yet on the list, indeed. However, nobody prevents you from sharing it and saying "I am going for a check up". His manager wouldn't have minded at all.

Also, sometimes it's just reading the f news. It's a global thing, everybody want it or not knows about this virus.

Fair enough, I would probably have asked my manager (who probably would have known I was in Italy). We do have APAC travel policies in place. Not sure about other countries. But if I were in the situation where I was coming back from Italy I would probably have asked (as an exempt employee who could work from home anyway) if I should self-quarantine out of caution. I would probably not have gone for a check-up if I felt fine. It's up to HR/Travel of course but things are moving quickly.

According to Wikipedia, Milan airport has 28m passengers per year, about 79k per day.

While northern Italy has highest concentration of cases outside Asia, the likelihood that any individual passenger is infected is very low and the likelihood that /one of them/ is infected, and had already traveled on, is very high.

I think that if we truly want to keep people safe, we should stop making assumptions about how low the risk is, etc. All it takes is that you are in that low percent and that's it. I am not saying we should start panicking, however, leveraging modern tools (remote work) whenever possible is key to reduce the risk even further. It's just prevention.

If your coworker is a danger to you then your whole office was exposed and should be quarantined also.