Hospital-acquired pneumonia in children: the role of respiratory viruses.

The most frequent agents of pneumonia acquired by children in the hospital are viruses. The characteristics of these nosocomial viral agents differ appreciably from the more classical bacterial nosocomial infections. The viral agents tend to be more contagious, with normal children being as susceptible as the predisposed, high-risk child. The epidemiology of these hospital-acquired infections tends to mimic the patterns of activity of the respiratory viruses in the community. The major causes of nosocomial pneumonia in children are, therefore, the epidemic respiratory viruses--respiratory syncytial virus, the influenza viruses, and the parainfluenza viruses. Respiratory syncytial virus is the most important and frequent of these, causing nosocomial infection in up to 45% of the contact children on infant-toddler wards during community outbreaks. About half of the nosocomial infections involve the lower respiratory tract in these young children. Severe and fatal disease is most likely to occur in neonates and children with underlying cardiac, pulmonary, and immunodeficiency disease. The frequency of lower respiratory tract involvement and nosocomial influenza and parainfluenza viral infections is less, but may pose a serious threat in nurseries and to certain groups of compromised children. The potential hazard of these viral agents on pediatric wards is heightened by the fact that they are frequently not recognized, the incentive and facilities for their diagnosis are often limited, and clinically they may mimic bacterial disease. The source of the nosocomial infections, which may be trivial illnesses in personnel or other patients, may not be suspected, and limiting the spread is difficult.(ABSTRACT TRUNCATED AT 250 WORDS)