Getah virus (GETV), belonging to the genus Alphavirus within the family Togaviridae, is a mosquito-borne virus that causes fever, rash, and edema in horses and fatalities and pregnancy disorders in pigs. It has caused occasional outbreaks in horse populations in Japan, China, and India, and endemic areas are gradually expanding, particularly in Asia and Oceania. In this study, we isolated a new GETV strain from Culex tritaeniorhynchus mosquitoes collected from Nagasaki Prefecture, Japan in 2022. Phylogenetic analysis revealed that this new strain, 22IH8, is more closely related to previous Chinese strains than to the strains prevalent in Japan in the 2010s. Furthermore, some amino acid substitutions in the viral proteins of strain 22IH8 were found to be common with those in previous Chinese strains. These results suggest that 22IH8 strain may have recently invaded the Japanese archipelago from mainland Asia. The antiserum against the current vaccine strain, MI-110, showed high neutralization activity against the 22IH8 strain indicating the efficiency of the current vaccine for horses in Japan.

The effect of antibodies elicited by bivalent mRNA vaccines (original and omicron BA.1) on preventing coronavirus disease 2019 (COVID-19) onset in the presence of the XBB variant remains unknown. A prospective cohort study conducted at Chiba University Hospital examined healthcare workers who received their sixth vaccination with the Pfizer-BioNTech COVID-19 bivalent mRNA vaccine (original and omicron BA.1). Researchers quantitatively measured serum anti-spike (S) antibody levels. Participants not infected during the 60-day observation period after vaccination had significantly higher S antibody titers than those who were newly infected (27756 U/mL, 95% CI [24988-30831 U/mL] vs. 15321 U/mL, 95% CI [10824-21688 U/mL], p<0.05). The risk of infection decreased by 84% when the S antibody titer exceeded 15500 U/ml. Neutralizing antibody titers against the XBB.1.16 and XBB.1.42 variants were higher in age- and sex-matched noninfected individuals than in newly infected individuals during the post-vaccination observation period. S antibody titers were highly correlated with neutralizing antibody titers. In conclusion, after the sixth COVID-19 vaccination with the bivalent mRNA vaccine (original and omicron BA.1), high S antibody titers correlated with disease prevention, even in the presence of XBB variants.

In 2021, vaccines against SARS-CoV-2 were developed, and the Omicron variant emerged. This study compared the characteristics, treatments, and mortality of patients with coronavirus disease 2019 (COVID-19) between 2022 and 2020-2021, using administrative claims data linked with vaccine records in a Japanese city. We identified patients underwent COVID-19 antigen or polymerase chain reaction tests and were diagnosed with COVID-19. Patient characteristics, treatments, and mortality were compared between 2022 and 2020-2021 among those diagnosed with COVID-19 and those who died. We identified 26,262 patients with COVID-19. The mortality in 2022 was lower than that in 2020-2021 (0.6% vs. 1.7%; P<0.01). Patients in 2022 were significantly less likely to receive oxygen therapy, high-flow nasal oxygenation, mechanical ventilation, steroid, or tocilizumab than those in 2020-2021. Among the deceased, the proportion of those aged ≥65 years was significantly higher in 2022 than in 2020-2021 (98.4% vs. 88.6%). On logistic regression, older age, male, and ≥3 comorbidities were associated with higher mortality, whereas ≥3 vaccinations were associated with lower mortality. Patients with COVID-19 in 2022 were less likely to require respiratory care or succumb to the disease. Older patients were more likely to die in 2022 than in 2020-2021.

Immunofluorescence methods to detect seasonal human coronavirus (HCoV)-OC43 in nasopharyngeal swab specimens using cell lines have not yet been established. A human rectal adenocarcinoma cell line (HRT-18) was exposed to the specimens obtained from patients with upper respiratory tract infections. Immunofluorescence staining was conducted with the combination of human serum containing the HCoV-OC43 anti-spike protein antibody and a fluorescence-labeled anti-human antibody. Positive staining in HRT-18 cells was detected after exposure to specimens obtained from nine of the eleven patients in which HCoV-OC43 RNA was detected using the FilmArray method. Increased supernatant viral RNA levels were also detected in HRT-18 cells exposed to specimens obtained from four of five patients. In contrast, positive staining was not detected in HRT-18 cells exposed to six patient specimens that tested negative for RNA from seventeen types and subtypes of respiratory viruses, including HCoV-OC43. The cells inoculated with the established strain HCoV-OC43 (ATCC VR-759) also showed positive staining. These findings suggest that the replication-competent HCoV-OC43 in the specimens could be detected via immunofluorescence staining of HRT-18 cells with human serum. It may be possible to obtain positive staining for viruses other than HCoV-OC43 using this method.

This study aimed to investigate the combination of the four regions of Helicobacter pylori vacA with cagA, cagE, dupA genes and cagA-EPIYA motifs to identify the most likely combination that could be used as a disease determinant marker in the Moroccan population. A total of 838 H. pylori-positive samples were obtained from consenting patients, that were previously analyzed by PCR to characterize vacA-s, -m, and -i regions; cagE status; and cagA 3' region polymorphism, were used to characterize vacA-d region and to determine dupA gene status. The analysis showed the predominance of the less virulent combination {vacA(s2m2i2d2)dupA(-)cagE(-)cagA(-)}, and showed that the risk of gastric cancer is 13.33 fold higher (95% confidence interval [CI] = 1.06-166.37) in patients infected with strains harboring vacA(s1m1i1d1)dupA(-)cagE(+)cagA(2EPIYA-C) compared to patients with gastritis without lesions and infected by H. pylori strains harboring vacA(s2m2i2d2)dupA(-) cagE(-)cagA(-). Infection with strains harboring the vacA(s1m1i1d1)dupA(+)cagE(+)cagA(1EPIYA-C) genotype combination represented a risk factor for both gastric ulcer and duodenal ulcer than gastritis without lesions; odds ratio (OR) =16 (95% CI = 1.09-234.24) and OR = 12.39 (95% CI = 1.09-140.81), respectively. These results suggest that the combination of the active form of vacA genotypes, dupA gene status, and the number of EPIYA-C motifs may be helpful markers for discriminating between several gastric diseases.

Evidence about which types of mask are effective in preventing infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is limited. We examined which mask types were effective against SARS-CoV-2 infection in a cluster setting in Japan. We retrospectively reviewed data from a cluster of COVID-19 cases that occurred at a manufacturing company in mid-August 2021. We included a total of 87 individuals who reported the type of mask worn. We dichotomized the types of mask into non-woven masks or other types of mask, such as cloth or urethane masks. We then examined the associations between the mask type and SARS-CoV-2 infection using logistic regression analysis, adjusting for potential confounders. Participants who wore non-woven masks were less likely to be infected with SARS-CoV-2 (9.7%) compared with those who wore other types of mask (26.7%). After adjusting for potential confounders, wearing a non-woven mask was significantly associated with a reduced risk of infection compared with wearing other mask types (odds ratio = 0.10, 95% confidence interval: 0.01 to 0.80). Non-woven masks were found to be more effective in preventing SARS-CoV-2 infection in a cluster setting than other types of mask, such as cloth or urethane masks.

An active epidemiological investigation of COVID-19 cases in the Setagaya Ward of Tokyo revealed that household transmission was the main route of spread. This study aimed to identify factors associated with household transmission in patients diagnosed with COVID-19 and cohabitants, during the wild-type (WT) (December 2020) and Alpha-variant (AV) (May 2021) epidemics. Factors in index cases significantly associated with household transmission of both WT and AV virus, included more than 3 days from onset to diagnosis (WT: risk ratio [RR] 1.44, 95% confidence interval [CI] 1.16-1.79; AV: RR 1.66, 95% CI 1.32-2.08), and a household size of three or more (WT: RR 1.37, 95% CI 1.10-1.72; AV: RR 1.29, 95% CI 1.05-1.59). Household transmission of WT was also significantly associated with the index case being aged ≥65 years (RR 2.39, 95% CI 1.26-4.54) and symptomatic at diagnosis (RR 3.05, 95% CI 1.22-7.63). Among cohabitants, factors associated with household transmission included being the spouse/partner of the index case (WT: RR 1.68, 95% CI 1.34-2.10; AV: RR 1.97, 95% CI 1.59-2.43) and at least 3 days from onset to diagnosis of the index case (WT: RR 1.48, 95% CI 1.21-1.82; AV: RR 1.86, 95% CI 1.52-2.28). Early diagnosis and isolation are effective for preventing household transmission.

The persistence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among wildlife populations poses a potential risk for the emergence of novel variants. Therefore, monitoring SARS-CoV-2 infections in animals is crucial. As urban rodents live in close proximity to human habitats, there is a concern that they may be a potential source of zoonoses. To examine the prevalence of SARS-CoV-2 in rodent populations, we analyzed 128 serum samples and 129 oral swabs collected from 128 brown rats (Rattus norvegicus) and two black rats (Rattus rattus) captured for pest control purposes in Tokyo, Japan, between May and December 2023. A virus-neutralizing test using the omicron variant revealed no evidence of SARS-CoV-2 infection. Real-time reverse transcription- PCR of oral swabs did not detect any SARS-CoV-2 RNA-positive rats. These results indicate a low probability of SARS-CoV-2 circulation among rat populations in Tokyo.

The spread of antimicrobial resistant organisms (AROs) poses a major threat to animal and human health. In Japan, the estimated disability-adjusted life years (DALYs) due to ARO infections is 137.9 per 100,000 persons, with methicillin-resistant Staphylococcus aureus (MRSA) being the main contributor. Factors that can contribute to DALYs in Japan include younger age and a higher number of deaths in patients with MRSA bacteremia. Moreover, longer hospital stays may contribute to the higher rates of MRSA bacteremia in Japan than in western countries. We reviewed the diagnostic procedure combination data collected from January 1, 2016 to December 31, 2020, in an acute care hospital in Tokyo, Japan. We found that the median time from admission to MRSA bacteremia onset was 26 days, which is longer than that observed in western countries however similar to that in South Korea. Furthermore, our cohort was older than those in the United States and South Korea, potentially contributing to the higher number of years of life lost in Japan. These results underscore the need to develop strategies to reduce hospitalization rates in Japan. Larger multicenter studies are needed to comprehensively evaluate the economic and health burdens of MRSA bacteremia in Japan.

While a live-attenuated Yellow fever (YF) vaccine is known to elicit durable immunity, antibody titers may wane after vaccination. This study evaluated the long-term immunity after vaccination against YF among individuals who reside in Korea and received vaccination with YF virus-17D prior to international travel. Serum was collected between December 2018 and December 2019 at the National Medical Center, Republic of Korea from YF vaccine recipients who were vaccinated more than five years prior to sample collection. Long-term immunity against YF was assessed using three serological assays: IgG enzyme-linked immunosorbent assay (ELISA), immunofluorescence assay (IFA), and focus reduction neutralization test (FRNT). Sixty seven subjects were enrolled. The overall positivity rates for FRNT, IFA and ELISA were 97.0%, 86.6% and 26.9%, respectively, in a time-variable, cross-sectional sample of the cohort. While 93.8% (15/16) of samples collected ≥10 years post-vaccination remained positive by FRNT, a significant inverse correlation was observed between FRNT titer and interval after vaccination (r=-0.385, p=0.001). Humoral immunity against YF was well preserved among the Korean individuals who were more than five years post-vaccination. IFA testing yielded results similar to FRNT testing, which may justify further development of the IFA to screen for waning immunity among those with previous YF vaccination.

Dengue viruses enter dermal macrophages which are derived from other tissues after mosquito bites. We examined chemotactic factors derived from the dengue vector mosquito, Aedes albopictus, toward a RAW264 murine macrophage cell line. We found that Elizabethkingia anophelis that was isolated from mosquitoes exhibited migration-inducing activity toward RAW264 cells. The active substances were extracted using ethyl acetate to induce chemotactic movements. Chemotactic activity was eluted in the several fractions using the reversed-phase chromatography, suggesting that multiple substances were responsible for the activity. We isolated three bacterial colonies from the wild A. albopictus mosquitoes collected in Toyama Park, Tokyo prefecture, Japan. The bacterial 16S rRNA gene sequences were the most similar to those of Lonsdalea quercina. These bacteria also exhibited migration-inducing activity toward RAW264 cells. The migration-inducing activity of mosquito bacteria might be a new aspect of mosquito-mediated viral infections.

Japanese spotted fever (JSF) is a tick-borne rickettsial disease prevalent in western Japan, with an increasing incidence and geographical distribution. This retrospective study aimed to describe the clinical features of JSF and identify factors associated with its severe form. We included adult patients with laboratory confirmed JSF in Nagasaki prefecture from 2010 to 2021. Severe JSF was defined by the presence of altered mental status, low blood pressure, or low oxygen saturation. In total, 65 JSF cases were diagnosed. Common symptoms were fever (87%), rash (48%), and fatigue (48%) with eschars detected in 50 (79.4%) of patients. Thirty-eight (60.3%) patients were initially diagnosed with non-JSF conditions. Twenty-one (33.3%) cases were categorized as severe JSF, including one death. Pre-hospital factors associated with severe JSF included age ≥75 (adjusted odds ratio [aOR] 37.53, 95% confidence interval [CI] 3.03-465.38), male sex (aOR 26.5, 95% CI 4.23-166.00), and a treatment delay ≥4 days from onset (aOR 5.96, 95% CI 1.13-31.60). This study highlights diagnostic challenges of JSF due to its non-organ-specific clinical presentation. Delayed initial treatment, advanced age, and male sex significantly increase the risk of severity. It is crucial to further raise awareness of JSF among clinicians and residents in endemic areas.

We report the case of a 77-year-old Japanese woman with neuromyelitis optica spectrum disorder, treated with 15 mg of prednisolone daily, who presented with acute septic shock and altered consciousness due to Dolosigranulum pigrum bacteremia. Intravenous extracellular fluids and broad-spectrum antibiotics were administered as an initial treatment. However, the patient died shortly after admission. We performed 16S rRNA sequencing and analyzed the murJ gene. A phylogenetic tree constructed using the neighbor-joining method showed that the strain belonged to clade C3, according to the classification proposed by Flores Ramos et al. Although D. pigrum, a commensal bacterium of the upper respiratory tract, is rarely associated with infections, it occasionally causes serious infections. Accumulation of clinical and bacteriological data is crucial for understanding the pathogenicity and infections associated with this organism.

Helicobacter pylori, Epstein-Barr virus and human papillomavirus are three pathogens associated with various human cancers. This study aimed to investigate the role of these pathogens in gastric cancer in Moroccan population. For this, a retrospective study has been conducted on participants attending the gastroenterology department of Hassan II University Hospital of Fez. A total of 279 participants were enrolled. H. pylori, EBV and HPV were detected and genotyped by PCR. In results, a significant association has been established between H. pylori, EBV and gastric cancer. 93.4% and 43.3% of gastric cancer cases are related to H. pylori and EBV respectively (p≤0.01). H. pylori-EBV co-infection is responsible of 31.6% of gastric cancer cases (p<0.01). Correlation between pathogens genotypes and gastric cancer shows 54.6% of GC EBV positives are carrying the 30 bp deletion in LMP1gene, while 16% of gastric cancers cases are carrying high-risk genotypes of HPV (p=0.21). The obtained results highlight the possible role of co-infection in gastric cancer development.

The aim of this study was to describe the clinical, histopathological, and immunohistochemical characteristics of MPX and offer meaningful insights into the clinicopathology of MPX. We recruited eight men who had sex with men diagnosed with MPX based on positive results from MPX Virus (MPXV)-specific polymerase chain reaction. Skin biopsies were obtained from four selected lesions, including typical and atypical lesions. Histopathological examinations of atypical solitary ulceration revealed infiltrating inflammatory cells predominantly composed of plasma cells and lymphocytes, forming a "sleeve" around the superficial vessels of the dermis. These features might be misinterpreted as indicative of cutaneous syphilis infection. Meanwhile, typical pustular lesions displayed central necrotic epidermis accompanied by perivascular inflammatory infiltrate dominated by neutrophils, as well as ballooning and reticular degeneration of keratinocytes. Additionally, multinucleated keratinocytes and eosinophilic cytoplasmic inclusions known as Guarnieri's bodies were also observed. Importantly, this study represented the pioneering report on immunohistochemical detection of MPXV A29 and A35 proteins in skin lesions, distinguishing it from previous studies that focused on detecting vaccinia virus protein. The anti-MPXV A29 antibody exhibited robust cytoplasmic staining specifically within affected keratinocytes in both adjacent epidermis and hair follicles, thereby it could contribute to the diagnosis of MPX, especially for cases with atypical skin lesions.

Escherichia albertii is an emerging foodborne pathogen causing diarrhea. Though various animals, especially poultry, serve as reservoirs, the transmission of E. albertii among reservoirs and the risk to humans remain unclear. This study investigated an E. albertii infected infant with poultry exposure and collected samples from contact persons, poultries, and environment to better understand the transmission dynamics of E. albertii. One E. albertii isolate from contact person, seven isolates from poultries, and six isolates from environment were recovered, respectively. Whole genome sequencing analysis showed that eight strains derived from poultry or environment and classified as ST4633, shared great similarity (cgSNP ≤ 20). However, the patient-derived strain ESA311 had a cgSNP difference of 1165 with human strain ESA339, and differed from poultry and environmental strains (cgSNP range 2417 to 14997), suggesting a distant relatedness. Whole genome phylogeny showed several human-derived E. albertii strains were clustered with those from animal origins. Our results suggested that family-breeding poultry constituted a possible reservoir of E. albertii, with the environment acting as a crucial vector for the spread of these bacteria, posing a risk to humans. Further poultry surveillance is needed to elucidate public health risks associated with E. albertii infection.

Clostridium perfringens, which produces C. perfringens enterotoxin (CPE), is a major causative agent of food poisoning owing to its gastrointestinal symptoms. Genotyping is important for identifying the etiological agent in outbreaks of C. perfringens. We attempted to genotype strains isolated from an outbreak of food poisoning in Toyama in 2023 using single nucleotide polymorphism (SNP) analysis. The strains of C. perfringens were isolated from a piece of curry food consumed by all patients and from the feces of the patients and employees. The cpe gene was detected in isolates from patients and curry food. The cpe-negative isolates were found in patients who consumed curry foods and in employees. The results of the SNP analysis suggest that the patient- and curry-derived isolates were likely from the same source but were unlikely to be related to the employee-derived isolates. The results of the SNP and pulsed-field gel electrophoresis (PFGE) analyses were consistent, indicating that the patient- and curry-derived isolates came from the same source. SNP analysis, a whole-genome-based genotyping method, is a promising alternative to the traditional PFGE method. Further studies are needed to accumulate more experience with genotyping using SNP analysis for the epidemiological investigation of outbreaks of C. perfringens.

In Japan, as elsewhere, the COVID-19 pandemic affected the notification trends of respiratory syncytial virus (RSV) infection. Here, we describe the epidemiological trends of RSV cases among children reported during 2018-2021 in Japan, based on the national surveillance system. Compared to 2018 and 2019, 2020 saw an unprecedented decrease in RSV notifications per sentinel site. However, 2021 experienced an unseasonably early and high peak in week 28 (peak week in 2018 and 2019: week 37) with a large resurgence in notifications, nationwide and across regions. Regarding age, compared to 2018 and 2019, the number and proportion of cases aged 2, 3, and ≥4-years increased substantially in 2021 but the number of cases aged <1 year decreased slightly. Furthermore, in 2021, the ratio of notifications per site from outpatient clinics to hospitals increased, suggesting a proportionate increase in clinically milder case diagnoses. Notably, RSV-attributed deaths from vital statistics also dropped substantially in 2020 and rebounded in 2021, but were fewer than in 2018 or 2019. While RSV incidence likely declined in 2020 (possibly from COVID-19 countermeasures) and increased in 2021, notifications in 2021 appeared to be associated with milder presentations. Given unpredictable RSV epidemiology, continuous monitoring and pluralistic assessments are imperative.

We assessed case fatality rates (CFRs) in cases aged ≥70 years in 10 Japanese prefectures (14.8 million residents) diagnosed between January 2022 and March 2023, when the Omicron variant was dominant in Japan. We selected incident reports on 283,052 study subjects from participating Public Health Centers adhering to the Infectious Diseases Control Law. Cases were passively followed up until the end of their isolation, date of death or 28 days after the COVID-19 diagnosis, whichever occurred first. We calculated age-standardized CFRs with 95% confidence intervals (CI) using the Japanese population aged 70-79, 80-89 and ≥90 in 2022 divided into 16 subgroups according to the period of COVID-19 diagnosis. The total overall CFR was 1.59% (95% CI 1.55-1.64); it ranged between 0.67% (95% CI 0.38-0.96, May 23-June 19) and 2.58% (95% CI 2.36-2.80, January 31-February 27). We observed three peaks of age-standardized CFRs paralleling the 6, 7 and 8 endemic COVID-19 waves driven by Omicron in Japan (2.2% January 31-February 27, 1.0% July 18-August 14 and 1.6% December 26-January 22, 2023, respectively). Population-based CFRs for Omicron variant COVID-19 in Japanese aged ≥70 years remained <3% throughout the period January 2022-March 2023, including during three large endemic waves in this country.

This study aims to understand the clinical characteristics of severe fever with thrombocytopenia syndrome (SFTS) and screen risk factors for the prognosis. This retrospective study collected the epidemiological, demographic, and clinical and laboratory data of 101 patients with SFTS. Patients were divided into survival and deceased groups, and then logistic regression model was used to evaluate the association between predictors and prognostic variables. A joint detection factor model was constructed, and a receiver operating characteristic (ROC) curve was drawn. A nomogram was established using the R language, and its efficiency in the diagnosis of SFTS was evaluated using the Calibrate curve. Patients in the deceased group were more likely to show an elder age, a shorter hospitalization stay, renal failure and multiple organ failure compared with that of the survival group. There were statistical differences in the neutrophil percentage, lymphocyte percentage, neutrophil-to-lymphocyte ratio, platelet (PLT), AST, AST/ALT, blood urea nitrogen, lactate dehydrogenase, hydroxybutyrate dehydrogenase, thromboplastin time and activated partial thromboplastin time between the two groups. Lymphocyte percentage, PLT, and AST/ALT were independent risk factors for mortality in SFTS patients. We established a prediction model for SFTS mortality with good efficiency.

We estimated the seroprevalence of anti-SARS-COV-2 IgG in different island groups in Okinawa. A cross-sectional sero-survey was repeated in three periods between July 2020 and February 2021. A total of 2683 serum samples were collected from six referral medical centers, each covering a separate region in Okinawa. In the main island, the seroprevalence was 0.0% (0/392, 95% CI: 0.0-0.9), 0.6% (8/1448, 0.2-1.1), and 1.4% (8/582, 0.6-2.7) at the 1, 2, and 3 sero-survey, respectively. In the remote islands, the seroprevalence was 0.0% (0/144, 95% CI: 0.0-2.5) and 1.6% (2/123, 0.2-5.8) at the 2 and 3 survey, respectively. The case detection ratio was 2.7 (95% CI: 1.3-5.3) in the main island and 2.8 (0.7-11.1) in the remote islands during the 3 survey. The case detection ratio was the highest in people aged 20-29 years (8.3, 95% CI: 3.3-21.4) in the main island and in those aged 50-59 years (14.1, 2.1-92.7) in the remote islands, suggesting under-reporting of clinical cases by the surveillance system in these subgroups. A sero-survey during an emerging infectious disease epidemic can be useful for validating the reliability of the surveillance system by providing the case detection ratio.