Viral etiology of acute respiratory infections in infants and young children.

114 children with acute respiratory infections were investigated to detect the viral etiological agents. The following methods were used: the direct immunofluorescence technique for the rapid diagnosis from tracheobronchial aspirates and the serological reactions--hemaglutinoinhibition and complement fixation reaction--to determine the increase of antibodies titres. Of 55.2% respiratory infections with a viral etiology, 60.3% represent acute infections of the lower respiratory tract. Due to the influenza epidemic reported between October 1996 and February 1997 (with a higher number of cases than in the last 5 years), most viral respiratory infections were caused by influenza viruses (57.14%). The direct immunofluorescence technique proved to be sensitive and specific in detecting the viral etiological agents which caused respiratory infections. Thus, using this technique, a positive diagnosis was made in 68.2% of cases, of which 49.2% were positive by the hemagglutination and complement fixation reactions, too. The test specificity could have been higher if the pathological products had been prelevated within the first three days after the onset of the disease.