Clinical and epidemiologic characteristics of respiratory syncytial virus subgroups A and B infections in Santa Fe, Argentina

Respiratory Syncytial Virus (RSV) has two major antigenic groups, A and B. The implications of these variants in the epidemiology and pathogenesis of RSV infection are not well defined. This study was undertaken to compare th e two RSV subgroups in patients admitted to hospital. Clinical and epidemio logic features of RSV subgroups in children under 30 months of age with pro ven RSV acute lower respiratory infections were examined during 4 winters f rom 1993 to 1996 in Santa Fe, Argentina. RSV typing was carried out with mo noclonal antibodies in nasopharyngeal cells by indirect immunofluorescence. Of the 177 RSV positive nasopharyngeal aspirates obtained from 1993 to 199 6, 85 (48%) were available for typing. Seventy-three (85.9%) specimens were identified as Subgroup A and 12 (14.1%) as Subgroup B. Except in 1993, in which only Subgroup A was detected, both variants circulated throughout the epidemic season. Subgroup A infections produced more severe disease than S ubgroup B infections, as assessed by the length of the hospital stay and th e use of respiratory support. This difference was age related, being eviden t in infants 0-6 months old. Patients with Subgroup B infections were also significantly less frequently breast-fed (95% vs. 75% for A and B subgroups , respectively; P = 0.04). It is concluded that the severity of disease in Argentinian patients admitted with acute RSV infections may be associated w ith Subgroup A strains as determined by a serogrouping method. J. Med. Viro l. 61:76-80, 2000. (C) 2000 Wiley-Liss, Inc.