Epidemiologic Trends and Distributions of Imported Infectious Diseases Among Travelers to Japan Before and During the COVID-19 Pandemic, 2016 to 2021: A Descriptive Study.

BACKGROUND: Little is known about the trends of imported infectious diseases among travelers to non-endemic countries during the novel coronavirus disease 2019 (COVID-19) pandemic. This article aimed to describe those among travelers to Japan. METHODS: This is a descriptive study based on national surveillance data. Imported infectious disease cases were defined as those with a reported overseas source of infection among 15 diseases pre-selected based on the probability and impact of importation. The number of notified cases from April 2016 to March 2021 were described by disease and time of diagnosis. The relative ratio and absolute difference in case counts-both by number and per arrival-were calculated by disease comparing those from the pandemic period (April 2020-March 2021) to the pre-pandemic period (April 2016-March 2020). RESULTS: A total of 3,524 imported infectious disease cases were diagnosed during the study period, including 3,439 cases before and 85 cases during the pandemic. The proportionate distribution of diseases changed but notification counts of all 15 diseases decreased during the pandemic. Accounting for arrivals, however, seven diseases showed a two-fold or greater increase, with a notable absolute increase per million arrivals for amebiasis (60.1; 95% confidence interval [CI], 41.5-78.7), malaria (21.7; 95% CI, 10.5-33.0), and typhoid fever (9.3; 95% CI, 1.9-16.8). CONCLUSION: The epidemiology of imported infectious diseases changed during the pandemic. While the number of imported infectious disease cases decreased, the number of cases per arrivals increased considerably both in relative and absolute terms for several diseases of public health and clinical importance.

Multiphoton-driven Photocatalytic Defluorination of Persistent Perfluoroalkyl Substances and Polymers by Visible Light.

Perfluoroalkyl substances (PFASs) and fluorinated polymers (FPs) have been extensively utilized in various industries, whereas their extremely high stability poses environmental persistence and waste treatment. Current decomposition approaches of PFASs and FPs typically require harsh conditions such as heating over 400°C. Thus, there is a pressing need to develop a new technique capable of decomposing them under mild conditions. Here, we demonstrated that perfluorooctanesulfonate (PFOS), known as a "persistent chemical," and Nafion, a widely utilized sulfonated FP for ion-exchange membranes, can be efficiently decomposed into fluorine ions under ambient conditions via the irradiation of visible LED light onto semiconductor nanocrystals (NCs). PFOS was completely defluorinated within 8-h irradiation of 405-nm LED light, and the turnover number of the C-F bond dissociation per NC was 17200. Furthermore, 81% defluorination of Nafion was achieved for 24-h light irradiation, demonstrating the efficient photocatalytic properties under visible light. We revealed that this decomposition is driven by cooperative mechanisms involving light-induced ligand displacements and Auger-induced electron injections via hydrated electrons and higher excited states. This study not only demonstrates the feasibility of efficiently breaking down various PFASs and FPs under mild conditions but also paves the way for advancing toward a sustainable fluorine-recycling society.

Coronavirus Disease 19 (COVID-19) Vaccine Effectiveness Against Symptomatic Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection During Delta-Dominant and Omicron-Dominant Periods in Japan: A Multicenter Prospective Case-control Study (Factors Associated with SARS-CoV-2 Infection and the Effectiveness of COVID-19 Vaccines Study).

BACKGROUND: Although several coronavirus disease 2019 (COVID-19) vaccines initially showed high efficacy, there have been concerns because of waning immunity and the emergence of variants with immune escape capacity. METHODS: A test-negative design case-control study was conducted in 16 healthcare facilities in Japan during the Delta-dominant period (August-September 2021) and the Omicron-dominant period (January-March 2022). Vaccine effectiveness (VE) against symptomatic severe acute respiratory syndrome coronavirus 2 infection was calculated for 2 doses for the Delta-dominant period and 2 or 3 doses for the Omicron-dominant period compared with unvaccinated individuals. RESULTS: The analysis included 5795 individuals with 2595 (44.8%) cases. Among vaccinees, 2242 (55.8%) received BNT162b2 and 1624 (40.4%) received messenger RNA (mRNA)-1273 at manufacturer-recommended intervals. During the Delta-dominant period, VE was 88% (95% confidence interval [CI], 82-93) 14 days to 3 months after dose 2 and 87% (95% CI, 38-97) 3 to 6 months after dose 2. During the Omicron-dominant period, VE was 56% (95% CI, 37-70) 14 days to 3 months since dose 2, 52% (95% CI, 40-62) 3 to 6 months after dose 2, 49% (95% CI, 34-61) 6+ months after dose 2, and 74% (95% CI, 62-83) 14+ days after dose 3. Restricting to individuals at high risk of severe COVID-19 and additional adjustment for preventive measures (ie, mask wearing/high-risk behaviors) yielded similar estimates, respectively. CONCLUSIONS: In Japan, where most are infection-naïve, and strict prevention measures are maintained regardless of vaccination status, 2-dose mRNA vaccines provided high protection against symptomatic infection during the Delta-dominant period and moderate protection during the Omicron-dominant period. Among individuals who received an mRNA booster dose, VE recovered to a high level.

SARS-CoV-2 Variants and Age-Dependent Infection Rates among Household and Nonhousehold Contacts.

To determine the effects of age and variants of concern on transmission of SARS-CoV-2, we analyzed infection rates among close contacts over 4 periods in Toyama Prefecture, Japan. Among household contacts, odds of infection were 6.2 times higher during the period of the Omicron variant than during previous periods, particularly among children and adolescents.

Nationwide epidemiologic and genetic surveillance of hepatitis E in Japan, 2014-2021.

Hepatitis E virus (HEV) is an emerging causative agent of acute hepatitis. To clarify the epidemiology of HEV and characterize the genetic diversity of the virus in Japan, nationwide enhanced surveillance and molecular characterization studies of HEV in Japan were undertaken from 2014 to 2021. In total, 2770 hepatitis E cases were reported, of which 88% were domestic cases, while only 4.1% represented cases following infection abroad. In addition, 57% of domestic infections occurred in males aged in their 40s-70s. For domestic cases, infection via pork meat consumption continued to be the most reported route. Analysis of the 324 sequences detected between 2016 and 2021 showed that the majority of domestic HEV strains belong to Genotype 3a (G3a) and G3b. In contrast, six of eight cases of G1 HEV reflected infection abroad. Our results suggest that HEV is circulating widely in Japan, with genotypes G3a and G3b being most prevalent. Continued surveillance is necessary to monitor future trends and changes in the epidemiology of HEV in Japan.

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.

Social and Behavioral Factors Associated with Lack of Intent to Receive COVID-19 Vaccine, Japan.

Persons in Japan who did not intend to receive COVID-19 vaccines after widespread rollout were less likely than others to engage in preventive measures or to be afraid of getting infected or infecting others. They were also not less likely to engage in potentially high-risk behaviors, suggesting similar or higher exposure risks.

Epidemiology of Coronavirus Disease Outbreak among Crewmembers on Cruise Ship, Nagasaki City, Japan, April 2020.

In April 2020, a coronavirus disease (COVID-19) outbreak occurred on the cruise ship Costa Atlantica in Nagasaki, Japan. Our outbreak investigation included 623 multinational crewmembers onboard on April 20. Median age was 31 years; 84% were men. Each crewmember was isolated or quarantined in a single room inside the ship, and monitoring of health status was supported by a remote health monitoring system. Crewmembers with more severe illness were hospitalized. The investigation found that the outbreak started in late March and peaked in late April, resulting in 149 laboratory-confirmed and 107 probable cases of infection with severe acute respiratory syndrome coronavirus 2. Six case-patients were hospitalized for COVID-19 pneumonia, including 1 in severe condition and 2 who required oxygen administration, but no deaths occurred. Although the virus can spread rapidly on a cruise ship, we describe how prompt isolation and quarantine combined with a sensitive syndromic surveillance system can control a COVID-19 outbreak.

Excess All-Cause Deaths during Coronavirus Disease Pandemic, Japan, January-May 20201.

To provide insight into the mortality burden of coronavirus disease (COVID-19) in Japan, we estimated the excess all-cause deaths for each week during the pandemic, January-May 2020, by prefecture and age group. We applied quasi-Poisson regression models to vital statistics data. Excess deaths were expressed as the range of differences between the observed and expected number of all-cause deaths and the 95% upper bound of the 1-sided prediction interval. A total of 208-4,322 all-cause excess deaths at the national level indicated a 0.03%-0.72% excess in the observed number of deaths. Prefecture and age structure consistency between the reported COVID-19 deaths and our estimates was weak, suggesting the need to use cause-specific analyses to distinguish between direct and indirect consequences of COVID-19.

Clinical Characteristics and Risk Factors for Severe Outcomes of Novel Coronavirus Infection, January-March 2020, Japan.

BACKGROUND: Notifications of novel coronavirus infections increased in early 2020 in Japan. We described characteristics of novel coronavirus infection cases and analyzed risk factors for severe outcomes. METHODS: Cases were persons with laboratory-confirmed novel coronavirus infection reported under national surveillance between January and March 2020. Clinical characteristics were described, and risk factors of (1) intensive care unit [ICU] admission and (2) invasive ventilation/death were analyzed using Poisson regression. RESULTS: Among the 516 cases analyzed, median age was 60 years (range: 1-97 years) and 285 (55%) were male. Common symptoms/signs were fever (375/475, 79%), cough (353/465, 76%), and pneumonia (245/387, 63%). Ten (2%) cases died. Of the 348 cases with data, 50 (14%) required invasive ventilation. Adjusted for each other, male gender and 1-year increase in age were associated with ICU admission (risk ratio [RR] 4.18; 95% confidence interval [CI], 1.69-10.32 and RR 1.05; 95% CI, 1.03-1.08, respectively) and invasive ventilation/death (RR 2.79; 95% CI, 1.49-5.21 and RR 1.06; 95% CI, 1.04-1.08, respectively). Diabetes, dyslipidemia, hyperuricemia, and lung diseases were also associated with severe outcomes. Of the 80 cases asymptomatic at hospitalization, 40 developed symptoms and five of them >70 years of age required invasive ventilation. CONCLUSIONS: The early stage of the novel coronavirus epidemic in Japan disproportionately affected the elderly. Older age, male gender, and underlying conditions were associated with severe outcomes. Notably, some elderly case-patients who were asymptomatic at diagnosis and promptly hospitalized still went on to develop severe disease, indicating the importance of careful monitoring of certain populations.

Increase in congenital syphilis cases and challenges in prevention in Japan, 2016-2017.

In Japan, the increase in congenital syphilis (CS) notifications has become a public health concern. We conducted a case series study to describe the characteristics of CS patients and their mothers. Of the 13 mothers who consented to participate, seven had regular prenatal care visits, including four who had tested negative at their first trimester syphilis screening. Only three mothers noted that their partners were tested, with all three partners being diagnosed with syphilis. Raising awareness for syphilis prevention during pregnancy, partner testing, and considering additional syphilis testing at the third trimester of pregnancy during times of increased syphilis prevalence is imperative.

Severe Acute Respiratory Syndrome Coronavirus 2 Infection among Returnees to Japan from Wuhan, China, 2020.

In early 2020, Japan repatriated 566 nationals from China. Universal laboratory testing and 14-day monitoring of returnees detected 12 cases of severe acute respiratory syndrome coronavirus 2 infection; initial screening results were negative for 5. Common outcomes were remaining asymptomatic (n = 4) and pneumonia (n = 6). Overall, screening performed poorly.

Epidemiology, molecular strain types, and macrolide resistance of Treponema pallidum in Japan, 2017-2018.

BACKGROUND: Japan has seen a substantial increase in syphilis cases since 2013 and Tokyo and Osaka prefectures accounted for about 40% of all cases in Japan. Therefore, focusing on these 2 prefectures, we assessed syphilis cases detected during 2017-2018, combining epidemiological information with molecular typing data. METHODS: Using data from surveillance reports, we described syphilis cases by gender, age, transmission route, and stage of syphilis. Clinical specimens were collected from syphilis patients in Tokyo and Osaka prefectures. Molecular typing was performed by analyzing Treponema pallidum arp, tpr, and tp0548 genes, with partial sequencing of the 23S rRNA genes for macrolide resistance. RESULTS: Between 2017 and 2018, the number of syphilis cases increased from 3934 to 4588 among males and 1895 to 2414 among females, with similar age and gender distributions during the period. The predominant strain type was 14d/f (71%, 73/103), found more frequently in women who have sex with men (86%, 25/29) and men who have sex with women (83%, 39/47) than in men who have sex with men (MSM) (33%, 9/27). The majority of the strains from heterosexuals (97%, 76/78) were macrolide-resistant, considerably higher than those from MSM (59%, 20/34). The molecular profiles in each sexual-transmission group remained similar during the 2 years. CONCLUSIONS: The epidemiological and molecular features of syphilis remained similar throughout the period, with consistent differences in strain type and macrolide resistance distributions between MSM and heterosexual cases. These findings suggest a predominantly heterosexual epidemic where the dynamics of syphilis transmission remained unchanged during 2017-2018.

Molecular Typing and Macrolide Resistance Analyses of Treponema pallidum in Heterosexuals and Men Who Have Sex with Men in Japan, 2017.

In recent years, syphilis notifications have increased dramatically in Japan. We carried out molecular typing and macrolide resistance analyses of Treponema pallidum subsp. pallidum samples collected from patients at four clinics and a hospital in Tokyo and Osaka prefectures in 2017. The macrolide resistant strain type 14d/f (SS14-like clade) was found in significantly more cases of syphilis among heterosexuals than in those among men who have sex with men (MSM); i.e., 79% (31/39) of the strains from heterosexuals were 14d/f compared to 37% (7/19) of those from MSM (odds ratio [OR], 6.6; 95% confidence interval [CI], 1.7 to 26.7; P = 0.002). In addition, 83% (50/60) of the strains were identified as macrolide resistant with an A2058G mutation in the 23S rRNA gene; 90% (35/39) of the strains from heterosexuals were macrolide resistant compared to 58% (11/19) of those from MSM. The odds of having the resistant mutation were considerably higher in the former (OR, 6.4; 95% CI, 1.3 to 33.5; P = 0.02). Heterosexual women and heterosexual men showed similar distributions, and the association remained the same when restricted to men. The strain type distribution and the prevalence of macrolide resistance differed substantially between syphilis strains from heterosexual cases and from MSM cases, suggesting distinct epidemiologic profiles for the two communities and providing important insight into the dynamics of syphilis in Japan.

Rapid Increase in Reports of Syphilis Associated With Men Who Have Sex With Women and Women Who Have Sex With Men, Japan, 2012 to 2016.

BACKGROUND: In Japan, syphilis reports have recently increased rapidly. However, unlike other developed countries where men who have sex with men (MSM) were associated with the rise, the increase in Japan has been attributed more to men who have sex with women (MSW) and women who have sex with men (WSM). We report on this increase based on surveillance data. METHODS: Syphilis is a notifiable disease requiring all laboratory-confirmed cases to be reported; stage and sex of the sex partner(s) suspected as the infection source are also reported. Focusing on primary and secondary (P&S) cases, we describe the temporal, demographic, and geographic distributions of reported cases in 2012 through 2016. RESULTS: A total of 7040 (64.0%) of 10,997 cases were P&S; the annual rate of increase was greatest for P&S and the proportion of P&S increased over time. Among P&S cases (1609 MSM, 2768 MSW, and 1323 WSM), MSW and WSM each surpassed MSM cases in 2016. Men were older with a wider age distribution (median, 37 years; interquartile range, 28-46 years) relative to women (median, 26 years; interquartile range, 21-34 years). Among women, 20- to 24-year-olds consistently had the highest reporting rate, reaching 9.0 per 100,000 in 2016. Congenital syphilis reports increased from 0.4 in 2012 to 1.4 per 100,000 live births in 2016. Although Tokyo prefecture had the highest reporting rate (3.98 per 100,000 person-years), the proportionate contribution from Tokyo decreased in 2016. CONCLUSIONS: Reports on P&S syphilis increased yearly among MSW and WSM. Young women seem to be at particular risk, and with increased reports of congenital syphilis, syphilis prevention and control is currently a public health priority in Japan.

Sociodemographic characteristics and clinical description of congenital syphilis patients and their mothers in Japan: a qualitative study, 2016.

Background In Japan, congenital syphilis (CS) notifications have increased recently. However, little is known about the CS cases or the clinical and sociodemographic characteristics of the patients' mothers. METHODS: Twelve cases of CS were reported through national surveillance in the period March-December 2016, and the mothers of seven patients were included in this study. The patients' mothers and physicians completed a self-administered questionnaire, providing sociodemographic and clinical information of the patients and their mothers. In addition, we explored the awareness and knowledge of, attitudes towards and practices regarding CS occurrence through semistructured interviews with the mothers. RESULTS: Of the seven CS patients, three were asymptomatic, with a range of non-specific clinical manifestations in the rest. The mothers tended to be of young age, unmarried and to have a history of commercial sex work, other sexually transmissible infections (STIs) and no or irregular prenatal care visits during pregnancy. Of the four mothers who had had regular prenatal care visits, two had tested negative for syphilis at the first trimester antenatal screening. Themes emerged that indicated challenges in preventing CS, including a lack of guidance or guidelines for physicians to consider testing for syphilis after the first trimester, lack of physicians' awareness or experience of syphilis or CS and a lack of awareness or knowledge in pregnant women regarding STIs. CONCLUSIONS: Key characteristics of recent CS patients and their mothers in Japan were revealed, identifying previously reported factors as well as new challenges. A holistic approach, designed to address challenges at the level of the healthcare system, healthcare provider and the pregnant woman and her partner will be important in preventing CS.

Enterohemorrhagic Escherichia coli outbreaks related to childcare facilities in Japan, 2010-2013.

BACKGROUND: Enterohemorrhagic Escherichia coli (EHEC) is an important cause of gastroenteritis in Japan. Although non-O157 EHEC infections have been increasingly reported worldwide, their impact on children has not been well described. METHODS: We collected national surveillance data of EHEC infections reported between 2010 and 2013 in Japan and characterized outbreaks that occurred in childcare facilities. Per Japanese outbreak investigation protocol, faecal samples from contacts of EHEC cases were collected regardless of symptomatic status. Cases and outbreaks were described by demographics, dates of diagnosis and onset, clinical manifestations, laboratory data, and relation to specific outbreaks in childcare facilities. RESULTS: During 2010-2013, a total of 68 EHEC outbreaks comprised of 1035 cases were related to childcare facilities. Among the 66 outbreaks caused by a single serogroup, 29 were serogroup O26 and 22 were O157; 35 outbreaks were caused by stx1-producing strains. Since 2010, the number of reported outbreaks steadily increased, with a rise in cases and outbreaks caused by stx1-producing O26. Of 7069 EHEC cases reported nationally in 2010-2011, the majority were caused by O157 (n = 4938), relative to O26 (n = 1353) and O111 (n = 195). However, relative to 69 cases of O157 (2%) associated with childcare facility EHEC outbreaks, there were 131 (10%) such cases of O26, and this trend intensified in 2012-2013 (O157, 3%; O26, 24%; O111, 48%). Among family members of childcare facility cases, the proportion of cases that were symptomatic declined with age; 10/16 cases (63%) aged 6 years or younger, 16/53 cases (30%) 6-19 years old, 23/120 cases (19%) 20-49 years old and 2/28 cases (7%) 50 years or older were symptomatic. Thirty one of the 68 outbreaks (46%) were classified as foodborne-related. CONCLUSIONS: Childcare facility EHEC outbreaks due to non-O157 serogroups, particularly O26 and O111, increased during 2010-2013. These facilities should pay extra attention to health conditions in children. As older family members of childcare facility cases appear to be less symptomatic, they should be vigilant about hand-washing to prevent further transmission.

Epidemiological situation of Ebola virus disease in West Africa.

After Guinea reported an outbreak of Ebola virus disease (EVD) in March 2014, EVD spread to neighboring Sierra Leone and Liberia in West Africa. Since then, the EVD outbreak spread over a wide geographic area among these three countries, and became the largest EVD epidemic ever with unprecedented numbers of confirmed cases and fatalities. As of April 2015, one year past the start of the outbreak, transmission is still ongoing. And, while six other countries, including those outside of the African continent (the United Kingdom, Spain, and the United States), have reported EVD cases, the source of the infection all originated from Guinea, Sierra Leone, or Liberia. As for the pathogen, Ebola virus, the route of transmission and associated prevention measures are well known, and change in the virulence or transmissibility of the virus has not been confirmed. However, there are specific factors that likely contributed to the unprecedented magnitude of the current EVD outbreak. In addition to the limited and poor medical and public health infrastructure in the affected countries, implementing appropriate responses rapidly was challenging for these countries, whose medical community, the general public, and governments had never experienced EVD before.