Cytokine Elevation in Sudden Death With Respiratory Syncytial Virus: A Case Report of 2 Children.

Respiratory syncytial virus (RSV) is the most common viral cause of bronchiolitis and pneumonia in young children worldwide. Premature birth, bronchopulmonary dysplasia, congenital heart disease, and Down syndrome are risk factors for high mortality and prolonged morbidity after RSV infection. Conversely, many previously healthy, full-term children are also admitted to the hospital because of RSV, and some of them experience severe sequelae or die due to the virus. Various complications of RSV infection have been reported, such as encephalopathy, encephalitis, and cardiomyopathy. However, the pathogenesis of serious cases in children without an underlying disease has not been elucidated. In this report, we present 2 RSV-related deaths of children who were born at full-term and developed normally up to the age of 19 months. Their cardiopulmonary arrests occurred within half a day after the onset of symptoms, such as cough and high fever. Many postmortem examinations were performed to investigate their unexpected deaths. Histopathological examinations revealed extensive bronchiolitis and mild pneumonia accompanying airway obstruction. Immunostaining revealed the presence of the virus mainly in bronchial epithelia, but not in alveoli. Complete brain edema was prominent, and encephalopathy was developing. Blood tests revealed that the IL-6 level was elevated more than >200-fold above normal, despite a normal C-reactive protein level. Because IL-6 may reflect the severity of bronchial epithelial damage and contribute to brain edema, an extreme elevation of IL-6 may predict the risk for sudden death in children with RSV infection.