How long is croup contagious? my son drank out nieces cup who had it last wk. her fever is gone and she's back at school. still has a cough. worry?

Unlikely...: Though one may contract a virus by touching a contaminated surface and then touching the eyes, nose or mouth, the timing of your niece's illness makes it unlikely. Croup is usually caused by a virus infection, most often a parainfluenza virus. After the third day of symptoms, a patient will begin to clinically improve.The cough may in itself represent a post-viral cough that may persist for weeks.