Clinical and laboratory profiles of hospitalized children with acute respiratory virus infection

Choi, Eunjin; Ha, Kee-Soo; Song, Dae Jin; Lee, Jung Hwa; Lee, Kwang Chul

In this study, viruses were detected in 74.0% of all ARI cases, but when cases of bacterial coinfection were excluded, viruses were detected in 69.1% of cases. Bacterial infection may be erroneously estimated because we counted all possible cases, even if not confirmed. Additionally, we did not routinely test for bacterial infection at presentation. Nevertheless, viral detection rates in this study were comparable to those of other studies. 8, 9) Although hRV, AdV, and RSV are the most prevalent viruses, RSV was more present as a single pathogen, whereas hRV and AdV were more seen with multiple pathogens. RSV, hRV, and PIV were the most prevalent single pathogens in patients younger than 3 years old. After the age of three, the prevalence of RSV decreased while the prevalence of IF and AdV increased, making hRV, IF, and AdV the most prevalent after three years of age. The younger age group shows higher virus positivity compared with the older age group, which may reflect prolonged shedding of respiratory viruses in young children. 10) Cases with multiple detected viruses are more likely to be males, while the sex ratio in single-virus cases is concordant with that of cases examined. The incidence of infectious disease is also reported higher among males. 11, 12) It is possible that after viral infection, viral clearance may be delayed in males, resulting in a greater chance for viruses to accumulate. The significance of multiple viral coinfections has been controversial. While it is unlikely to be associated with more severe illness, 9, 13, 14) specific pathogen pairs such as RSV with influenza virus may be associated with increased severity. 9) Studies report strong causal attribution of RSV, IF, and hMPV, less strong evidence for hRV and no attribution of AdV, hBV and hCV, [15] [16] [17] which is in agreement with the ratio of single to multiple detections of each virus in our study. Quantitative viral analysis may help to distinguish active infection from viral shedding in cases with multiple viral coinfection. 9) Because the clinical significance of multiple viral infections remains controversial and hard to interpret, we compared single-virus cases to understand characteristics of each virus. Seasonality of some respiratory viruses is an important clue for early recognition. In addition to the strong seasonal patterns observed with IF, RSV, and hMPV, it is interesting that RSV A and B have an apparent biennial seasonality. While hRV and AdV are prevalent throughout the year, seasonal patterns of viruses are discrete. Each respiratory viruses differ in seasonal onset as well as activity, but this can slightly vary from year to year. Knowing the seasonality of each virus will help to plan effective control strategies and to make epidemiological diagnosis. Analysis of virus-specific clinical profiles showed that cases of RSV A, RSV B, hBV, PIV, and hCV affect patients who are signifi cantly younger than those with IFA, IFB, AdV, and hEV ARIs. Premature birth history, and presence of congenital heart disease and chronic lung disease are not associated with any specific virus. While fever is a common symptom of ARI, cases of RSV and hRV are significantly afebrile. Infants younger than 6 months with RSV infection tend to be afebrile, which may be due to a lack of a pyrogenic cytokine response. 18, 19) While patients with afebrile RSV cases are significantly younger than febrile RSV cases (2.6 months vs. 11.4 months, P= 0.000 for RSV A, 4