Systematic review of the biology and medical management of respiratory syncytial virus infection.

Respiratory syncytial virus, the leading cause of serious upper and lower respiratory tract infection in infants and children, accounts for 125,000 hospitalizations and 450 deaths annually in the United States. It also may predispose to development of asthma later in life. Annual epidemics occur from November to April, and virtually all infants are infected by age 2. Immunity is not durable; hence, reinfection occurs throughout life, although subsequent infections are nearly always mild. Certain populations (eg, premature infants, infants with chronic lung disease, and immunocompromised individuals) are at risk for severe morbidity and have higher risk of mortality. Infection is spread to the nose and eyes by large droplets and direct contact with secretions, and fomites may remain infectious for up to 12 hours. Nosocomial infection is common. The virus infects airway ciliated epithelial cells, spreading by the formation of syncytia. Cellular debris and inflammation cause airway obstruction, hyperinflation, localized atelectasis, wheezing, and impaired gas exchange. Both humoral and cellular immune response are critical to ending the acute infection, but wheezing and reactive airways may persist for as long as 5-10 years after acute infection. No cure exists for respiratory syncytial virus infection, but commonly employed palliative treatments include oxygen, inhaled beta(2) agonists, racemic epinephrine, dornase alfa, systemic and inhaled corticosteroids, inhaled ribavirin, and nasopharyngeal suctioning. Infants suffering severe lower airways disease may require mechanical ventilation. Prophylactic measures include rigorous infection control and administration of polyclonal (RSV-IGIV [respiratory syncytial virus - immunoglobulin intravenous]) and monoclonal (palivizumab) antibodies. The cost of the prophylactic antibody treatment is high; it is cost-effective for only the highest risk patients. Development of a vaccine remains far in the future. Application of evidence-based clinical practice guidelines is making both out-patient and in-patient therapy as effective and economical as possible. Copyright 2003 Daedalus Enterprises