Japanese journal of infectious diseases最新文献

This study aimed to investigate the epidemiological and genetic characteristics of human astroviruses (HAstVs) detected during acute gastroenteritis (AG) outbreaks in Yokohama, Japan. We collected stool samples and epidemiological information between September 2017 and August 2023 and used real-time reverse transcription (RT)-PCR and/or RT-PCR to detect HAstV from 53 samples from 20 (3.1%) of the 648 virus-associated AG outbreaks during the study period. Of the 20 outbreaks investigated via sequencing, 13 were caused by classic HAstV, three by HAstV-MLB, and four were due to multiple genotypes, classic HAstV and HAstV-MLB. The strains detected in Yokohama were found to be closely related within their respective genotypes. The distribution of HAstV genotypes differed by age groups, with HAstV1 and HAstV-MLB1 primarily found in 0-3 year-olds, whereas HAstV4 typically occurred in individuals over 4 years of age. Of the 53 HAstV-infected patients, 49 (92.5%) experienced diarrhea, with 36 exhibiting only this symptom. Vomiting (18.9%) was less prevalent than diarrhea. There were no differences in the symptoms between individuals with classic HAstV and HAstV-MLB.

Hand, foot, and mouth disease (HFMD) caused by enteroviruses is common in children. Recently, coxsackievirus A6 (CVA6) has been identified as a major causative agent. In this study, we conducted a phylogenetic analysis of a part of the VP1 coding region of 194 CVA6 strains detected directly from 767 nasopharyngeal swab or stool samples of HFMD patients in Japan from 2019 to 2024. The detected CVA6 strains were classified into genotype D. Moreover, the strains detected from before 2019 to 2023 belonged to cluster (cluster 1 and 2), whereas the most of strains detected in 2024 belonged to another cluster (cluster 3). Genetic identity among all detected CVA6 strains was 89.1%-100%, and genetic identity within the cluster for each detected strain was 90.6%-100% for the before 2019 (cluster 1) strains, 92.6%-100% for the 2019-2023 (cluster 2) and 94.5%-100% for the 2024 (cluster 3) strains. Most of the strains detected in 2024 were similar to the strains detected in China in 2023, suggesting that the influx of new strains caused the 2024 outbreak in Japan. HFMD is one of the most prevalent diseases in the world and its pathogenicity and antigenicity may be altered. Surveillance of the influx of new strains from outside Japan will become increasingly important.

Klebsiella variicola, often misidentified as Klebsiella pneumoniae, is gaining recognition as a pathogen. This study reports the first human case of infection with K. variicola harboring bla_CTX-M-14 in Japan. MALDI time-of-flight mass spectrometry was used to confirm that clinical isolates from urine and blood cultures were K. variicola. The infection was successfully treated with cefmetazole. Whole-genome sequencing identified bla_CTX-M-14 in an 8,066 bp plasmid. Given the rarity of extended-spectrum beta-lactamase-positive K. variicola infections in Japan, this case highlights the importance of accurately identifying and monitoring multidrug-resistant pathogens.

Chronic inflammation and persistent immune activation (IA) during HIV infection are associated with non-AIDS complications. We investigated sociodemographic and clinical characteristics influencing IA and exhaustion (IE), and platelet activation (PA) in newly diagnosed people living with HIV (PLHIV) and identified modifiable factors for early interventions. We analysed baseline blood samples from 365 PLHIV participating in a trial investigating the effect of aspirin on IA, IE, and PA. We assessed levels of markers of monocyte activation (soluble CD14), platelet activation (soluble P-selectin), T-cell activation (CD4⁺ and CD8⁺ expressing CD69 and co-expressing CD38 and HLA-DR), and T-cell exhaustion (PD-1). The median (IQR) age of the participants was 37 (28, 45) years, with females comprising 64.7%. Advanced age significantly predicted IA and IE, but not PA. Markers of IA and IE, but not of PA, inversely correlated with CD4 counts, while directly with HIV viral load (HVL). We show that most Tanzanian PLHIV initiating antiretroviral therapy (ART) have low CD4 count, high HVL, with a considerable proportion aged above 50 years, characteristics associated with heightened IA and IE. Adjunctive therapy, when available, should target such population and at ART initiation to prevent morbidity and mortality associated with persistent IA and IE.

Tuberculosis (TB) is an endemic respiratory disease in several countries, including South Korea. The coronavirus disease 2019 (COVID-19) may pose greater risks to individuals with pre-existing respiratory diseases, but there are few reports on how the post-recovery state from TB affects COVID-19 infection and mortality. This study aimed to investigate the susceptibility and mortality of COVID-19 in patients with a history of TB. We retrospectively analyzed data from the National Health Insurance Service of Korea. We extracted individuals with TB from 2011 to 2019 and matched them with a population-based control group. The main outcomes were COVID-19 incidence and death within 30 days of infection. The study included 138,278 matched pairs of individuals with and without a history of TB. COVID-19 incidence was slightly lower in the TB group (38.0% vs. 38.4%, P-value = 0.023). Subgroup analysis showed significantly lower COVID-19 incidence in the pulmonary TB group compared to controls (P-value = 0.001). However, the mortality rate was higher in the TB group (0.9% vs. 0.7%, P-value < 0.001). This study showed that TB has a slightly protective effect against COVID-19 infection but increases the mortality rate. These findings will guide future research on the interaction between TB and COVID-19.

The present study developed a novel nano-structured nasal Bordetella pertussis vaccine candidate using encapsulating filamentous haemagglutinin (FHA) and pertussis toxoid (PTd) into N-trimethyl chitosan (TMC) with the help of CpG as an adjuvant and crosslinker (CpG-adjuvanted TMC/PTd-FHA), followed by physicochemical characterization and immune response evaluation after nasal administration. The TMC/CpG/PTd-FHA nanoparticle (NP) exhibited a particle size and zeta potential of 289.4 nm and +25.7 mV, respectively. The antigen/toxoid-loaded NPs exhibited >80% efficacy for encapsulation into polymer matrices, whereas in vitro antigen/toxoid release was found to be 95.18% after 96 hours. High immunization rates were observed in NP-treated mice with increased IgG and secretory IgA levels and proper capability to induce IFN-γ, IL-4, and IL-17 compared with the control group. Overall, nasal administration of the proposed approach, utilizing CpG as an adjuvant and crosslinker, could elicit humoral and Th1-type cellular immune responses, demonstrating promising potential as a vaccine delivery system.

After lifting travel bans imposed during the coronavirus 2019 pandemic, the number of reported measles cases in Japan started rising, culminating in 11 cases in Osaka Prefecture in 2024. We investigated the molecular epidemiology of these cases using 450 nucleotides of the C-terminal region of the nucleoprotein gene (N-450) and the noncoding region located between the matrix and fusion protein genes (MF-NCR). N-450 analysis revealed eight cases of genotype D8 and three of B3. Seven of the D8 cases were closely related to strains from Central Asia and Europe, harboring mutations in the primer binding region targeted by real-time PCR assays for measles virus. The remaining D8 case matched a strain from Thailand. All three B3 cases were identical to the strain detected in Vietnam in 2024. MF-NCR analysis of D8 cases revealed similar trends to those observed in the N-450 analysis. However, the B3 viruses from Vietnam differed by several bases from the closest related sequence and included a 6-base insertion. Given the resurgence of measles in Vietnam since 2024, the potential risk of continuous measles importation remains. Attention should focus on measles surveillance under circumstances of increased international human interactions, specifically the Exposition 2025 Osaka, Kansai in Japan.

Since we reported the first parechovirus A3-associated myalgia (PeVA3-M) outbreak in Yamagata in 2008 as an emerging disease, we have investigated PeVA3 infections as part of the National Epidemiological Surveillance of Infectious Diseases, Japan in sentinel hospitals/clinics and also performed a specific symptomatic surveillance targeting PeVA3-M. As PeVA3-M has only been reported from Japan, it is necessary to continue the above surveillance. In our surveillance from July 2022 to December 2023, we found 31 PeVA3 infections including three PeVA3-M and suspected cases using PCR and a virus isolation method. Further next-generation sequencing (NGS) analysis was performed for the representative isolates and their original specimens between 2022 and 2023 as well as those between 2003 and 2019. The NGS analysis showed that 7,245~7,309 and 7,118~7,287 nucleotides (98.7~99.8% and 97.1~99.4% compared with the reference strains) were available from 25 representative isolates and from 6 clinical specimens, respectively. This study indicated that the recombinant PeVA3 strains, which appeared in 2019, remained in circulation in Yamagata between 2022 and 2023. Furthermore, a NGS method is useful for the molecular epidemiological surveillance of PeVA3 infections, although improvements of the method used for the clinical specimens are required.

Incompletely resolved immune dysfunction in people living with HIV (PLWH) on antiretroviral treatment (ART) could differentially impact CD4+ and CD8+ T cell subsets. In this study, we investigated SARS-CoV-2 vaccine-induced CD4+ and CD8+ T cell responses in 26 PLWH on ART following third-dose mRNA vaccination. Spike-specific CD4+ and CD8+ T cell responses were assessed based on the expression of activation markers, CD137/OX40 and CD137/CD25, respectively, in response to stimulation with overlapping peptides spanning the spike protein. All participants showed spike-specific T cell responses, with CD8+ responses at a higher median frequency than CD4+. Interestingly, 5 participants who showed a higher frequency of spike-specific CD4+, relative to CD8+ T cells, were significantly younger and had higher CD4 counts pre-ART, in comparison to other participants. Further multivariate analysis revealed that only CD4 count pre-ART was an important predictor of elevated spike-specific CD4+ T cell responses; whereas no association was observed with neutralizing antibody (nAb) potency towards SARS-CoV-2 spike. Our results highlight heterogeneous immune functionality of vaccine-induced, SARS-CoV-2 spike-specific CD4+ and CD8+ T cells in PLHW on ART.

Evidence regarding the types of masks that are effective in preventing infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is limited. We identified the mask types that were effective against SARS-CoV-2 infection in a cluster setting in Japan. Data from a cluster of employees with coronavirus disease 2019 at a manufacturing company in mid-August 2021 were retrospectively reviewed. A total of 87 employees who reported the type of mask worn were included. The types of masks were dichotomized into non-woven masks or other types of masks, such as cloth or urethane masks. The association between mask type and SARS-CoV-2 infection was determined using logistic regression analysis after adjusting for potential confounders. Participants who wore non-woven masks were less likely to be infected with SARS-CoV-2 (9.7%) than those who wore other types of masks (26.7%). After adjusting for potential confounders, wearing a non-woven mask was significantly associated with a reduced risk of infection compared to wearing other types of masks (odds ratio, 0.10; 95% confidence interval, 0.01-0.80). Non-woven masks were more effective in preventing SARS-CoV-2 infection in a cluster setting than other types of masks, such as cloth or urethane masks.