吉川 哲史

BACKGROUND: Kawasaki disease (KD) onset has been suggested to be associated with infections and various environmental factors. However, research on whether the delivery type plays a role in KD development is limited. This study investigated whether cesarean section (CS) or vaginal delivery (VD) is associated with KD onset using a large administrative claims database in Japan. METHOD: We conducted a case-control study using the JMDC Claims Database from January 2005 to December 2021. Data on children born via CS or VD and their mothers were collected. KD patients were identified from the source population, and controls without KD were randomly selected based on sex, age and registration time, each matched to 4 controls using a risk-set sampling technique. We analyzed the association between delivery type and KD onset using multivariate conditional logistic regression, defining KD as the primary outcome based on specific criteria. RESULTS: Case-control matching created 3363 pairs of cases (n = 3363) and controls (n = 13,363). The proportions of CS, maternal age, Charlson Comorbidity Index, presence of older siblings and low birth weight infants were significantly different between the cases and controls. In the multivariate analysis, KD onset was associated with CS [odds ratio (OR): 1.12; 95% confidence interval (CI): 1.02-1.24], the presence of older siblings (OR: 1.11; 95% CI: 1.02-1.21), lower birth weight (1001-2500 g) (OR: 1.22; 95% CI: 1.04-1.43) and antibiotic use (OR: 1.12; 95% CI: 1.02-1.24). CONCLUSIONS: The risk of developing KD may be influenced by the delivery type (CS or VD), the presence of older siblings, low birth weight and antibiotic use.

Human herpesviruses 6A and 6B (HHV-6A/B) can integrate into the germline, resulting in inherited viral DNA-now proposed to be called "endogenous HHV-6A/B (eHHV-6A/B)." Present in 0.2-3% of humans, this integrated DNA is passed to offspring and may reactivate, posing health risks such as angina or lupus. To reduce confusion caused by varied terminology, researchers advocate using "eHHV-6A/B" for inherited forms and reserving "chromosomally integrated" for somatic integrations only.

The 12th International Conference on Human Herpesvirus (HHV)-6A, HHV-6B, and HHV-7 was held in Himeji, Japan, from March 25 to March 27, 2025. It attracted over 120 basic, translational, and clinical scientists from 17 countries. Important new information was presented regarding: studies of viral genes and proteins; mechanism of chromosomal integration of the viral genome; host cell interactions; inherited chromosomally integrated HHV-6A/B, also called endogenous HHV-6A/B); the role of the viruses in drug-induced hypersensitivity syndrome (DIHS)/drug reaction with eosinophilia and systemic symptoms (DRESS); the role of the viruses as opportunistic pathogens in immunocompromised people; the role of the viruses in diseases of the central nervous system, particularly encephalopathy, post-COVID neurological conditions, complex febrile seizures, and synucleinopathies; and the possible role of the viruses in non-Hodgkin lymphoma and autoimmune diseases, including systemic lupus erythematosus. In this review, we summarize many of the oral presentations. The full text of the Conference Abstracts is available at: https://hhv-6foundation.org/wp-content/uploads/2025/06/Abstracts_FINAL-3.10.25.pdf.

BACKGROUND: Pediatric acute hepatitis of unknown etiology (AHUE) has been reported globally since April 2022. The purpose of the present study was to investigate the impact of coronavirus disease 2019 (COVID-19) pandemic on the incidence of AHUE in Japan. METHODS: A nationwide survey of AHUE was conducted in 2510 pediatric hospitals by the Japan Pediatric Society. We retrospectively reviewed AHUE cases, defined by the World Health Organization's working case definition, and compared the incidence, clinical characteristics, and causative pathogens before the COVID-19 pandemic period (pre-pandemic, January 2017 to December 2019) and during the pandemic period (pandemic, January 2020 to June 2022). RESULTS: In total, 707 cases (450 pre-pandemic, 257 pandemic) were reported. The median age was 3 years (interquartile range (IQR): 1-9 years), and 43.8% were female. The number of AHUE cases decreased significantly in the pandemic period (102.8 cases/year) compared with the pre-pandemic period (150.0 cases/year). Investigations of pathogens causing AHUE demonstrated that the most common cause was unknown, accounting for 64% and 75% of cases in the pre-pandemic and pandemic periods, respectively. Among those whose pathogens were identified, the most common pathogens were Epstein-Barr virus (9.6%), cytomegalovirus (6.2%), and influenza (4.0%) in the pre-pandemic, and 7.0%, 3.5%, and 0.4%, respectively, in the pandemic period. SARS-CoV-2 and adenovirus were only 2.7% and 1.9%, respectively, in the pandemic period. CONCLUSIONS: The number of AHUE cases decreased during the COVID-19 pandemic compared with the pre-pandemic period, and no increase in adenovirus-associated disease or severe cases was observed in Japan.