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.
Croup is usually a viral infection and may be caused by many different viruses, including those responsible for the common cold and influenza. Rarely, it is caused by a bacterial infection. Croup is more common and concerning in children between 6 months and 3 years of age and rarely occurs in children over 6 years of age. It is more commonly seen from late fall through the early winter months.