Resurgence of human metapneumovirus infection and influenza after three seasons of inactivity in the post-COVID-19 era in Hokkaido, Japan, 2022-2023.

Following the coronavirus disease 2019 (COVID-19) outbreak in February 2020, incidences of various infectious diseases decreased notably in Hokkaido Prefecture, Japan. However, Japan began gradually easing COVID-19 infection control measures in 2022. Here, we conducted a survey of children hospitalized with human metapneumovirus (hMPV), influenza A and B, and respiratory syncytial virus infections in 18 hospitals across Hokkaido Prefecture, Japan, spanning from July 2019 to June 2023.

Changing Patterns of Infectious Diseases Among Hospitalized Children in Hokkaido, Japan, in the Post-COVID-19 Era, July 2019 to June 2022.

Background: Many reports have reported a reduction in respiratory infectious diseases and infectious gastroenteritis immediately after the coronavirus disease 2019 (COVID-19) pandemic, but data continuing into 2022 are very limited. We sought to understand the current situation of various infectious diseases among children in Japan as of July 2022 to improve public health in the post-COVID-19 era.

Methods: We collected data on children hospitalized with infectious diseases in 18 hospitals in Japan from July 2019 to June 2022.

Sequence analysis of a feline- and porcine-origin G3P[9] rotavirus A strain in a child with acute gastroenteritis in Japan.

We isolated the rare G3P[9] rotavirus strain RVA/Human-wt/JPN/R11-035/2015/G3P[9] from a 2-year-old girl presenting with vomiting and diarrhea who had daily contact with cats in Japan, 2015. Full-genome analysis revealed that the R11-035 strain had an AU-1-like genetic constellation, except for the NSP3 (T) gene: G3-P[9]-I3-R3-C3-M3-A3-N3-T1-E3-H6. Phylogenetic analysis showed that strain R11-035 is closely related to human/feline-like human strains, and only the NSP3 (T1) gene was clustered together with Taiwanese porcine strains.

Characteristics of intussusception among children in Hokkaido, Japan, during the pre- and post-rotavirus vaccine eras (2007-2016).

Aim: To analyse the epidemiology of intussusception in Hokkaido Prefecture, Japan during a 10-year period spanning the introduction of the rotavirus (RV) vaccine (2007-2016).

Methods: Using a standard questionnaire, a retrospective surveillance was conducted across 17 hospitals with paediatric beds in Hokkaido Prefecture. We compared the data between the pre-vaccine era (2007-2011) and post-vaccine era (2012-2016).

Genotypes and transmission routes of noroviruses causing sporadic acute gastroenteritis among adults and children, Japan, 2015-2019.

Noroviruses (NoVs) are major causes of acute viral gastroenteritis at all ages worldwide. The molecular epidemiology of sporadic cases remains poorly understood, especially in adults. Additionally, no studies have analyzed the transmission route in sporadic acute gastroenteritis.

Rotavirus vaccination in Japan: Efficacy and safety of vaccines, changes in genotype, and surveillance efforts.

In Japan, a monovalent rotavirus vaccine (RV1) and a pentavalent rotavirus vaccine (RV5) were launched as voluntary vaccinations in November 2011 and July 2012, respectively. Rotavirus (RV) vaccine coverage in Japan increased from 30.0% in 2012 to 78.

Molecular characterization of the first human G15 rotavirus strain of zoonotic origin from the bovine species.

Group A rotaviruses (RVAs) infect a wide variety of mammalian and avian species. Animals act as a potential reservoir to RVA human infections by direct virion transmission or by contributing genes to reassortants. Here, we report the molecular characterization of a rare human RVA strain Ni17-46 with a genotype G15P[14], isolated in Japan in 2017 during rotavirus surveillance in a paediatric outpatient clinic.

Molecular and clinical characterization of the equine-like G3 rotavirus that caused the first outbreak in Japan, 2016.

Since 2013, equine-like G3 rotavirus (eG3) strains have been detected throughout the world, including in Japan, and the strains were found to be dominant in some countries. In 2016, the first eG3 outbreak in Japan occurred in Tomakomai, Hokkaido prefecture, and the strains became dominant in other Hokkaido areas the following year. There were no significant differences in the clinical characteristics of eG3 and non-eG3 rotavirus infections.

Predictive factors of response to IVIG in pediatric immune thrombocytopenic purpura.

Background: Immune thrombocytopenic purpura (ITP) is commonly treated with i.v. immunoglobulin (IVIG).