EPIDEMIOLOGY AND DIAGNOSIS OF RESPIRATORY SYNCYTIAL VIRUS-INFECTIONS

Winter outbreaks of respiratory syncytial virus (RSV) infections are the cause of frequent acute lower respiratory diseases in infants. The group A or B of RSV was determinated from infants hospitalized in Caen, France, over eight consecutive epidemics from 1982 to 1990. In 1985-86, 1986-87 and 1988-89, both groups were present in almost equal numbers, and a predominant strain was observed in 1987-88: group A, and in 1989-90: group R Therefore the relative frequency of group A strains increased from 1983 to 1988, whereas the group B decreased, as if there was a gradual change of the predominant group into another over a period of about 5 years. A greater clinical severity was observed with group A strains during 3 consecutive outbreaks from 1987 to 1996. The need to differentiate severe RSV bronchiolitis from bacterial or other viral pneumonia has prompted the development of rapid viral diagnostic techniques. Direct microscopic detection of RSV antigen in respiratory secretions by the indirect fluorescent antibody test or ELISA are the procedure of choice. Both methods have advantages over culture of convenience or speed, and can appear of superior sensitivity because of the rapid inactivation of RSV in nasal specimens. Attempts to use a rise in serum antibody either IgM as a diagnostic aid have been desapointing.