Season One Edit. Beckett's initial relationship with Castle was strained because she viewed him as immature and reckless. She suspected (correctly) that Castle was using his research as an excuse to pursue her, and only tolerated his presence at the request of Captain Montgomery.
What causes croup in children. Croup in children is most often caused by the parainfluenza virus, a respiratory virus not related to the flu. But it can also be caused by other respiratory viruses including the flu. Yes, croup is contagious.
Children are most likely to get croup between 3 months and 5 years of age. As they get older, it is not as common because the windpipe is larger and swelling is less likely to get in the way of breathing. Croup can occur at any time of the year, but it is more common in the fall and winter months.