william schaffner with vanderbilt university medical center says measles is the single most contagiousents that it causes only mild illness. >> it is an absolutely nasty infection, and i would not wish a single child to have to experience measles. >> reporter: health officials are warning of a possible exposure at the indianapolis children's museum during the solar eclipse after an infected person from out of state travelled there for the viewing. anyone exposed could show symptoms as late as april 29th based on the incubation period. symptoms are high fever, cough, runny nose, red-eyes, white spots in the mouth, and a rash that starts on the hairline and face and spreads. >> the measles virus can get down into your chest and cause pneumonia. even more seriously, it can get into your brain and cause inflammation. >> reporter: doctors say the best way to avoid infection is to get vaccinated. nicole sganga, cbs news, washington. >>> and that's the "overnight news" for this thursday. reporting from the nation's capital, i'm olivia gazis. >>> this is cbs news flash. i'm shanelle kaul in ne