An infection that you got in the hospital. Happens every so often, something hospitals are loath to disclose.

Note: Don't read this and panic about your gallbladder surgery next week.

What happens most of the time is that a humidifier or thermometer becomes contaminated and passed on to another patient. The odds of this happening are slim, thanks to new regulations and safety precautions. You're not going to get plague from the guy in the next room, there are air HEPA filters to stop that. This phrase is used more for doctors and nurses who touch an infected needle or catch a cold from a patient. While a patient treated for a broken rib may get pneumonia, the odds are very very low.

The main subject of Robin Cook's book Contagion