OBJECTIVETo investigate the prevalence of viral infections and putative association of viral infection with illness severity in young children with severe lower respiratory tract infection (LRTI) in Chongqing.

METHODRespiratory secretion specimens were collected from 119 hospitalized patients with severe pneumonia from December 2006 to March 2008.After being processed, the samples were detected for respiratory viruses including respiratory syncytial virus (RSV), adenovirus (ADV), human metapneumovirus (hMPV), human bocavirus (HBoV), parainfluenza virus 1, 2, 3 (PIV 1, 2, 3), influenza virus A and B (IVA and IVB) either by PCR or RT-PCR. Clinical data were analyzed along with virological data by using appropriate statistical methods.

RESULTViral pathogens were identified in specimens of 86 (72.3%) cases, among which RSV was detected in 49 (41.2%) patients. More than one virus was detected in 23 individual (26.7%) samples, of which 19 were dual positive for RSV and another virus. Bacterial cultures were performed for 69 patients. Both bacterial and viral pathogens were identified in 53 (76.8%) patients. Bacterial and viral coinfection was demonstrated in samples from 41 (59.4%) cases.

CONCLUSIONViral pathogens are the main etiology of severe pneumonia in young children in Chongqing area during the study period. RSV was the most frequent viral pathogens, followed by ADV and hMPV. Coinfection with respiratory common viruses was relatively common, though co-infection with viruses did not appear to aggravate the patients' condition.