Why is healthcare one of the only areas of US life where "socialism" seems to be anathema?

I'm a Brit, and I remember the days of real socialism over here, and I'm constantly amazed by people in the US who claim that there's something inherently unAmerican about socialised heathcare. After all, defence is socialised, policing is socialised, fire departments are socialised. How come only the idea of socialised healthcare makes people so jumpy over there? And will there come a day when the rabid fear of anything left wing that was drilled into America in its post-war anti-Communism days mellows to a point where socialised healthcare is a generally acceptable idea?