Unprecedented increase in syphilis cases among heterosexual men and women in Japan, 2021-2022.

Based on national surveillance data, we describe an unprecedented increase in syphilis case reports in Japan, with a surge in 2021-2022 reaching 10141 cases in Week 42, 2022, a 1.7-fold increase over the same period in 2021. This already represented the highest annual case count in nearly half a century; by Week 52, 2022, the number reached 12 966, far surpassing the 7978 cases in 2021. Predominantly affecting heterosexual men and young women, the proportionate increase in primary and secondary syphilis cases suggests a true increase in incidence. The syphilis surge during the pandemic poses a serious public health concern and underscores the importance of adequate testing and preventive measures.

Impact of the Coming-of-Age Day and ceremony on the risk of SARS-CoV-2 transmission in Japan: A natural-experimental study based on national surveillance data.

BACKGROUND: Quantifying the impact on COVID-19 transmission from a single event has been difficult due to the virus transmission dynamics, such as lag from exposure to reported infection, non-linearity arising from the person-to-person transmission, and the modifying effects of non-pharmaceutical interventions over time. To address these issues, we aimed to estimate the COVID-19 transmission risk of social events focusing on the Japanese Coming-of-Age Day and Coming-of-Age ceremony in which "new adults" practice risky behavior on that particular day. METHODS: Using national surveillance data in Japan in 2021 and 2022, we conducted difference-in-differences regression against COVID-19 incidences by setting "new adults" cases as the treatment group and the cases 1 year younger or older than these "new adults" as the control group. In addition, we employed a triple differences approach to estimate the risk of holding the Coming-Age ceremony by using a binary variable regarding the presence or absence of the ceremony in each municipality. RESULTS: We estimated the relative risks (RRs) of the Coming-of-Age Day as 1.27 (95% confidence interval [CI] 1.02-1.57) in 2021 and 3.22 (95% CI 2.68-3.86) in 2022. The RR of the Coming-of-Age ceremony was also large, estimated as 2.83 (1.81-4.43) in 2022. CONCLUSIONS: When planning large social events, it is important to be aware of the unique risks associated with these gatherings, along with effective public health messages to best communicate these risks.

Factors related to parenting stress among fathers of preschool children in Japan.

BACKGROUND: Even though fathers participate in childcare at a higher rate than before, there remains a lack of research on the factors that contribute to parenting stress among fathers. This study explored the socioeconomic and demographic factors associated with parenting stress among fathers of preschool children. METHODS: Our study included 17 645 fathers who participated in the 2016 Comprehensive Survey of Living Conditions in Japan. Parenting stress was assessed using a single question. Socioeconomic and demographic factors were predictors. Logistic regression analysis was conducted to estimate the odds ratio (OR) and 95% confidence interval (CI) for parenting stress. RESULTS: Overall, 6.6% fathers experienced parenting stress. Fathers with a youngest child aged 0-2 years were more likely to experience parenting stress than those with a youngest child aged 3-6 (OR: 1.45, 95% CI: 1.25-1.68). Compared with fathers who lived in two-parent households without grandparents, those who lived in single-father households (both with and without grandparents) were more likely to experience parenting stress (OR: 12.13, 95% CI: 5.60-26.29 and OR: 4.19, 95% CI: 2.04-8.60, respectively). Furthermore, there was a significant negative association between education and parenting stress. CONCLUSIONS: Having a child aged 0-2 years, single fatherhood, and higher education were associated with parenting stress among fathers of preschool children. Healthcare professionals need to be aware of these factors when supporting fathers in raising their children.

[Review on the influence of paternal involvement in childcare on mothers, children, and fathers].

Objectives　Recently, paternal involvement in childcare has been gaining public attention in Japan. However, studies on the influences of active paternal involvement remain scarce. This study aimed to review the findings on the influence of paternal involvement in childcare on mothers, children, and fathers themselves from studies conducted in Japan and published mainly after 2010. Additionally, we examined methodological issues that need to be addressed when researchers conduct studies on paternal involvement in the future.Methods　We reviewed 26 journal articles (22 in Japanese and 4 in English) from four databases: "Igaku Chuo Zasshi Web (Japana Centra Revuo Medicina History and Activities)," JSTPlus, JMEDPlus, and PubMed with conditions such as studies conducted in Japan, families with young children, and questionnaire-based quantitative studies. We described respondents (mothers, fathers, or both) and assessed paternal involvement in childcare, outcomes, and findings.Results　We reviewed studies on paternal involvement in childcare published in Japanese after 2010 and English after 2000 and observed two trends across the studies. The first was that if mothers acknowledge active paternal involvement in childcare, mothers' parenting stress seemed to be lower, and they seemed to be happier. Moreover, for children's health and development, active paternal involvement seemed to be associated with positive results, such as prevention of unintentional injuries and obesity. However, in the second trend, we observed that active paternal involvement, assessed by the fathers themselves, were often not associated with lower parenting stress among mothers. We also could not observe a consistent trend on the findings related to the influences on fathers, due to the limited number of studies. We observed that assessment of paternal involvement in childcare was inconsistent across studies included in this review.Conclusion　With more social pressure for fathers to be actively involved in childcare, public interest for the influence would be heightened. For future studies, better ways of assessing the quantity and content of paternal involvement in childcare need to be discussed.

Replacement of SARS-CoV-2 strains with variants carrying N501Y and L452R mutations in Japan: an epidemiological surveillance assessment.

Objective: Monitoring the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants is important due to concerns regarding infectivity, transmissibility, immune evasion and disease severity. We evaluated the temporal and regional replacement of previous SARS-CoV-2 variants by the emergent strains, Alpha and Delta. Methods: We obtained the results of polymerase chain reaction screening tests for variants conducted in multiple commercial laboratories. Assuming that all previous strains would be replaced by one variant, the new variant detection rate was estimated by fitting a logistic growth model. We estimated the transmission advantage of each new variant over the pre-existing virus strains. Results: The variant with the N501Y mutation was first identified in the Kinki region in early February 2021, and by early May, it had replaced more than 90% of the previous strains. The variant with the L452R mutation was first detected in the Kanto-Koshin region in mid-May, and by early August, it comprised more than 90% of the circulating strains. Compared with pre-existing strains, the variant with the N501Y mutation showed transmission advantages of 48.2% and 40.3% in the Kanto-Koshin and Kinki regions, respectively, while the variant with the L452R mutation showed transmission advantages of 60.1% and 71.9%, respectively. Discussion: In Japan, Alpha and Delta variants displayed regional differences in the replacement timing and their relative transmission advantages. Our method is efficient in monitoring and estimating changes in the proportion of variant strains in a timely manner in each region.