Condolences to everyone by the Milwaukee Road train station: Hope you're feeling better. How do I know you're ill?

Simple. I have a new smartphone app called "Sickweather," and it tracks illness in your immediate area. How? Does it listen for your hacking coughs, fix your location via GPS, cross-check with Walgreen Cold-and-Flu aisle trips, and upload it so the NSA and Chinese hackers can send you get-well cards?

No. It scans Facebook. Well, you say, what doesn't? The accuracy of the app depends on people staggering to their computer, feeling like achy sweaty sloths, and typing URGH I HAVE FLU so people can LIKE it, and companies can send you a coupon for something that makes you feel 17 percent better and tastes like blueberries grown in Chernobyl.

When I first opened it up, little markers indicating disease rained down on Minneapolis like the Judgement of Heaven, and any rational person would instantly run outside and daub an X on the front door in lamb's blood. (We were out. Had it on the list, too.) Downtown was a seething mass of SICK icons, concentrated in two areas: Right outside the Milwaukee Depot, and the Warehouse District.

The latter was the most interesting, because it said a Common Cold had been reported right in the middle of Washington Avenue. This means someone was walking across a busy street typing "I feel like I'm coming down with something" into Facebook, and may have had their status downgraded to "struck by bus." Unless that person is still there spinning 360 degrees while sneezing I don't think I have to worry. Likewise, the cluster of dozens of cold and flu cases at the corner of 2nd Avenue and 2nd Street — they happened 10 days ago, and that's as helpful as reading that someone down the street had the Crimean Blotch in 1947.

In short, it's useful only for paranoid hypochondriacs. Which is why it's now on my main screen and I'm checking it hourly. Here's the problem: I think my wife might be coming down with a cold, but she's not on Facebook. However will I know how she's doing?

jlileks@startribune.com • 612-673-7858