incubation period for croup
The incubation period, the time from exposure to HPIV to onset of symptoms, is generally 2 to 7 days. 1  HPIV-1 and HPIV-2 are most often associated with croup. 2  HPIV-1 often causes croup in children, whereas HPIV-2 is less frequently detected.he incubation period, the time from exposure to HPIV to onset of symptoms, is generally 2 to 7 days. 1  HPIV-1 and HPIV-2 are most often associated with croup. 2  HPIV-1 often causes croup in children, whereas HPIV-2 is less frequently detected.