Change Over Time in Seasonality and Severity of Children Hospitalized With Respiratory Syncytial Virus Infection in Japan.

BACKGROUND: Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis, and in temperate climates, late fall and winter epidemics of bronchiolitis are usually linked to RSV. In recent years in Japan, the RSV infection epidemic has occurred earlier, even during the hot season. This study aimed to evaluate the seasonal variation of RSV-associated hospitalizations over the past decade and the relationship between season and disease severity. METHODS: This was a retrospective single-center study. Hospitalized children were studied between 2011 and 2019. RSV was detected using rapid antigen detection tests. Clinical information was obtained from medical records, and patients were classified by 4 seasons of admission and analyzed for changes over time. RESULTS: Among 3750 children, 945 (25.2%) were RSV-positive. The seasonal proportion of hospitalized children who are RSV-positive showed a peak shift towards summer, with a turning point in 2016. Comparing 2011-2012 and 2018-2019, incidence increased from 6.8% to 46.3% during summer, whereas during fall decreased from 50.0% to 20.7% and decreased from 28.4% to 20.7% during winter ( P < 0.05). A similar trend was observed in the number of children requiring oxygenation in the earlier period; however, after the transition, there was no significant difference between seasons. CONCLUSIONS: Our findings showed that the RSV epidemic shifted to peak during summer until 2016. There was an association between seasonality and severity, such that many younger children were hospitalized during the autumn and winter and required more oxygen; however, after 2016, this difference was no longer observed.

Abnormal urinalysis on day 7 in patients with IgA vasculitis (Henoch-Schönlein purpura).

Rare progression to renal failure imposes a burden on children with IgA vasculitis (Henoch-Schönlein purpura, HSP). An abnormal urinalysis on day 7 (7d-UA) may be a surrogate marker for persistent nephritis, but this has not been established. We retrospectively analyzed the risk factors for persistent nephritis in a cohort of 138 children. Of 35 children with abnormal 7d-UA, 24 (69%) had an abnormal urinalysis 6 months after the diagnosis of HSP, which was significantly more than 6 of 103 children (6%) with normal 7d-UA (P < 0.0001). The negative predictive values for normal urinalysis and negative proteinuria 6 months after diagnosis were 0.94 (95% confidence interval [CI], 0.90-0.97) and 0.98 (95% CI, 0.95-0.99), respectively. When children with abnormal urinalysis 6 months after diagnosis were compared with those without, the following factors were significantly associated: age at diagnosis, abnormal urinalysis at diagnosis, abnormal 7d-UA, complement C3, steroid treatment, and presence of abdominal pain. However, multivariate analysis revealed that abnormal 7d-UA was the only significant risk factor for abnormal urinalysis 6 months after diagnosis (odds ratio 54.3, 95% CI 15.3-275, P = 1.89 × 10-6). Abnormal 7d-UA may be an independent risk factor for persistent nephritis, but this should be confirmed in a prospective study.