Lower respiratory tract infection in hospitalized children due to respiratory syncytial (RS) virus during a suspected epidemic period of RS virus in Delhi.

A study of 131 children below 5 years of age seeking hospitalization due to lower respiratory tract infections (LRTI), comprising 56 cases of bronchiolitis, 61 cases of bronchopneumonia, and 14 cases of other lower respiratory tract diseases showed significant occurrence of bronchiolitis in younger age groups (chi 2 = 79.21; P less than 0.001). Employing two rapid techniques, viz. immunofluorescent antibody technique (IFAT) and enzyme immunoassay (EIA) along with tissue culture, Respiratory Syncytial (RS) virus could be detected in higher percentage of bronchiolitis cases (54 per cent by both culture and IFAT, 70 per cent by EIA) compared to bronchopneumonia (36 per cent by both culture and IFAT, 49 per cent by EIA) and other LRTI cases (14 per cent each by culture, IFAT and EIA). The detection rate of RS virus was higher in the age group 0-6 months compared to the remaining age groups combined (7-60 months) in bronchiolitis cases irrespective of the technique employed while no such difference could be noted in bronchopneumonia. Eighteen (90 per cent) out of 20 specimens positive for RS virus by EIA, but negative by culture were found to be true positives as revealed by blocking test. In comparison to culture, sensitivities of IFAT, EIA, and EIA (by blocking test) were found to be 89, 94, and 94 per cent, respectively, while specificities of these techniques were found to be 92, 74, and 76 per cent, respectively. Higher detection rate of RS virus in the present study compared to earlier ones from India is attributed to application of EIA as well as selection of LRTI cases during a period of suspected epidemic of RS virus.