[Epidemiology of respiratory viral infection in 2004-2006.].
BACKGROUND
The information on the incidence, seasonal variation and clinical pattern of respiratory virus infections is very important for clinicians in managing their patients. This study was aimed to define the epidemiology of respiratory viral pathogens in Seoul and the neighboring areas from March 2004 to February 2006.


METHODS
A total of 6,533 specimens were cultured for respiratory viruses during the study period. Madin-Darby canine kidney (MDCK), LLC-MK2, and HEp-2 cells, or R-mix cells (Diagnostic Hybrids Inc., Athens, Ohio, USA) were used for culture. Influenza virus types A & B (Inf A & B), parainfluenza virus (PIV), respiratory syncytial virus (RSV), and adenovirus (ADV) were identified by indirect immuno-fluorescent staining. Medical records of the patients with positive virus cultures were reviewed retrospectively.


RESULTS
One or more viral agents were isolated from 1682 specimens (25.7%). The pathogens identified were RSV 37.2%, ADV 19.9%, Inf A 18.9%, PIV 17.5% and Inf B 6.4%. The most frequent pathogen of pneumonia and acute bronchiolitis was RSV and that of croup was PIV. Upper respiratory tract infections were more prevalent in adults and the most frequently caused by influenza virus. Influenza virus itself was more frequently isolated in children less than six years old, which was different from previous reports. Influenza virus was mostly isolated in the winter and spring, while RSV was usually isolated from early fall with a peak incidence in the winter. Inf A and RSV showed a dampening effect on the occurrence of other viruses during their major epidemic. PIV was mostly detected in the spring and summer. ADV was isolated throughout the whole year.


CONCLUSIONS
The epidemiological characteristics of respiratory virus infections in Seoul and the neighboring areas in 2004-2006, were similar to the findings of previous reports except for some minor changes. These findings could be useful to clinicians in managing their patients.