Le diagnostic rapide des infections à virus respiratoire syncytial (RS) par le titrage des IgM sériques (immunofluorescence indirecte)

Summary In January 1981, during an outbreak of respiratory diseases in babies aged between 1 and 3 months, 9 patients with severe bronchiolitis were hospitalized in a Pediatric ward and 11 cases occurred as nosocomial infections. For direct rapid diagnosis, pharyngeal swabs and nasal aspirations were obtained from 10 out of 11 patients at a late stage of the disease. The rapid detection of respiratory syncytial (RS) antigen was positive in only 2 cases and the virus isolation unsuccessful. For serological diagnosis, in 9 out of 16 cases, the “first” serum was collected 5 days or more after the onset of the disease. The indirect immunofluorescence (IF) test allowed us to make the diagnosis in 13/16 cases, while the complement fixation (CF) test remained negative. From November 1980 to January 1981, sera were collected from 32 children aged 2 to 14 years and 13 adults hospitalized for acute respiratory disease (bronchitis, bronchopneumopathis) and 35 adults (kidney grafted) submitted to a systematic survey. The indirect IF test was not found to be more sensitive than the CF test but it enabled us: o 1) to differenciate the primary infections from the reinfections; 2) to show detectable IgM in 11/17 cases of reinfections; 3) to make a rapid diagnosis of RS infection in 60% of the cases on a single serum while the CF test gave either a negative result (1 case) or only presumptive results (10 cases).