RELATIONSHIP BETWEEN CLINICAL SEVERITY OF RESPIRATORY SYNCYTIAL VIRUS-INFECTION AND SUBTYPE

The relationship between clinical severity of respiratory syncytial vi rus (RSV) infection and distribution of subtype A or B was investigate d. The data of 232 children, who were admitted with RSV infection or d iagnosed in the outpatient department of the Sophia Children's Hospita l, Rotterdam between 1992 and 1995, were studied. The diagnosis of RSV was confirmed by a direct immunofluorescence assay. Sub-typing was pe rformed by an indirect immunofluorescence assay using specific monoclo nal antibodies. Gender, age at diagnosis, gestational age and birth we ight, the presence of underlying diseases, feeding difficulties, the p resence of wheezing and retractions, respiratory rate, temperature, cl inical diagnosis at presentation, oxygen saturation (Sao(2)), carbon d ioxide tension (Pco(2)), and pH, characteristics of hospitalisation, a nd the need for mechanical ventilation were observed. Analysis was per formed on data from all patients diagnosed with RSV infection in the p eriod between 1992 and 1995 spanning three RSV seasons, and separately on the RSV season 1993-4. The outcome of the three year analysis (150 (64.7%) subtype A v 82 (35.3%) subtype B) was compared with the outco me of the season 1993-4, a mixed epidemic with 37 (60.7%) subtype A an d 24 (39.3%) subtype B isolates. None of the variables observed in the season 1993-4 differed significantly between RSV subtype A and B. Sim ilar results were obtained from the analysis in the period 1992 until 1995, with the exception of Pco(2) (a higher Pco(2) was found in subty pe A, p <0.001) and retractions (more retractions were noted in patien ts with subtype A, p=0.03). After correcting for possible confounders using regression analysis, these differences were not significant anym ore. The data indicate that there is no relationship between clinical severity of RSV infection and subtype.