OBJECTIVEAn outbreak of acute respiratory infections in children occurred in Beijing from November to December, 2002. To investigate the etiological agents of affected children who were in day care centers and primary schools.

METHODSThroat swab specimens were collected from one primary school children with acute respiratory infections visiting one outpatient department. After centrifuging, supernatant from the specimens were inoculated into MDCK and Hep-2 cells for virus isolation and pallets for viral antigen detection and using indirect immunofluorescent assay on common respiratory viruses. Nested polymerase chain reaction was used at the same time for detection of respiratory viruses and Mycoplasma pneumoniae (Mp).

RESULTSA total number of 80 specimens were collected during the outbreak. Among them influenza B virus were detected from 18 specimens, with a positive rate of 22.5% (18/80) while Mp were detected from 13 specimens, with a positive rate of 16.3% (13/80). Influenza A3 were also detected from 2 patients (2.5%, 2/80). However, influenza A1, RSV, adenovirus and parainfluenza viruses were not found from these specimens. Influenza B virus and Mp were detected simultaneity in two specimens and influenza A3 virus and Mp were detected in one specimen.

CONCLUSIONThe outbreak of acute respiratory infection in children during the period of investigation was caused by both influenza B virus and Mp.