Pericardial effusion in an infant with severe respiratory syncytial virus bronchiolitis.

Respiratory syncytial virus is the most common pathogen causing lower respiratory tract infection in infants. Respiratory syncytial virus infection is also associated with a number of extrapulmonary manifestations, including the cardiac system. Pericardial effusion, however, is a very rare occurrence with respiratory syncytial virus infection. We report a very young infant with respiratory syncytial virus bronchiolitis whose clinical course was associated with pericardial effusion, treated conservatively.