Molecular Epidemiology of Respiratory Syncytial Virus during 2019-2022 and Surviving Genotypes after the COVID-19 Pandemic in Japan.

To evaluate the changes in respiratory syncytial virus (RSV) collected between 2019 and 2022, we analyzed RSV-A and RSV-B strains from various prefectures in Japan before and after the COVID-19 pandemic. RT-PCR-positive samples collected from children with rapid test positivity at outpatient clinics in 11 prefectures in Japan were sequenced for the ectodomain of the G gene to determine the genotype. Time-aware phylogeographic analyses were performed using the second hypervariable region (HVR) of the G gene from 2012 to 2022. Of 967 samples, 739 (76.4%) were found to be RSV-positive using RT-PCR. RSV peaked in September 2019 but was not detected in 2020, except in Okinawa. Nationwide epidemics occurred with peaks in July 2021 and 2022. The genotype remained the same, ON1 for RSV-A and BA9 for RSV-B during 2019-2022. Phylogeographic analysis of HVR revealed that at least seven clusters of RSV-A had circulated previously but decreased to two clusters after the pandemic, whereas RSV-B had a single monophyletic cluster over the 10 years. Both RSV-A and RSV-B were transferred from Okinawa into other prefectures after the pandemic. The RSV epidemic was suppressed due to pandemic restrictions; however, pre-pandemic genotypes spread nationwide after the pandemic.

The indicators for early blood transfusion in patients with placental abruption with intrauterine fetal death: a retrospective review.

BACKGROUND: Placental abruption (PA) with intrauterine fetal death (IUFD) is associated with a high risk of postpartum hemorrhage (PPH) resulting from severe disseminated intravascular coagulation (DIC). Therefore, blood products that are sufficient for coagulation factor replacement must be prepared, and delivery should occur at referral medical institutions that are equipped with sufficient blood products and emergency transfusion protocols. We retrospectively reviewed the records of patients with PA and IUFD (PA-IUFD) to identify possible factors that may indicate the need for early blood transfusion and investigated whether the Japanese scoring system for PPH can be applied in such cases. METHODS: We used a database of 16,058 pregnant patients who delivered at Yokohama City University Medical Center between January 2000 and February 2016. Thirty-three patients were diagnosed with PA-IUFD before delivery and categorized into two groups-blood transfusion and non-transfusion-to compare the maternal characteristics and pregnancy outcomes. RESULTS: In patients with PA-IUFD, the transfusion group exhibited significantly more blood loss; lower fibrinogen levels and platelet counts; higher levels of fibrin degradation products (FDP), D-dimer, and prothrombin time; and a tendency for tachycardia on admission, compared to the non-transfusion group. Many patients in the transfusion group had normal fibrinogen levels on admission but later displayed markedly decreased fibrinogen levels. The Japan Society of Obstetrics and Gynecology (JSOG) DIC score was significantly higher in the transfusion than in the non-transfusion group. CONCLUSIONS: In PA-IUFD, the fibrinogen level, platelet count, D-dimer, FDP, heart rate, and JSOG DIC score on admission may indicate the need for blood transfusion. However, even with normal fibrinogen levels on admission, continuous monitoring is indispensable for identifying progressive fibrinogen reductions in patients with PA-IUFD.

Incidence and risk factors of severe lacerations during forceps delivery in a single teaching hospital where simulation training is held annually.

AIM: This study was conducted to evaluate the incidence of severe lacerations during forceps delivery and the risk factors associated with such delivery in a hospital where simulation training is held annually. METHODS: The medical records of 857 women who underwent forceps delivery at term with singleton cephalic presentation from 2010 to 2015 were reviewed. The relationship between clinical characteristics and birth canal trauma was analyzed. Birth canal trauma included third and fourth degree perineal lacerations. Univariable and multivariable models of logistic regression were employed to estimate the raw odds ratio and were adjusted for cofactors with 95% confidence intervals. Statistical significance was defined as P < 0.05. RESULTS: The incidence of severe lacerations was 10.1%. Birth weight, fetal head station, the rate of malrotation and the number of extractions were higher in women with severe lacerations (P < 0.01), whereas the use of obstetric anesthesia was lower in women with such lacerations (P < 0.01). Neither the indication for forceps delivery nor the qualifications of the operator had any influence on the incidence of severe lacerations. CONCLUSION: The incidence of severe lacerations was relatively low. Risk factors for severe lacerations with forceps delivery were identified as birth weight, fetal head station, malrotation and the number of extractions. Obstetric anesthesia may protect against severe lacerations.

High frequency of repeated infections due to emerging genotypes of human respiratory syncytial viruses among children during eight successive epidemic seasons in Japan.

In eight successive seasons (2001 to 2009), a total of 726 human respiratory syncytial virus (HRSV) infections from a total of 1,560 children with acute lower respiratory tract illness were identified. Molecular analysis of the attachment (G) protein gene confirmed that 52 (7.8%) children were infected more than once with any of the 3 genotypes of HRSV-A (genotypes GA5, NA1, and NA2) and/or 6 genotypes of HRSV-B (genotypes BA4, BA5, and BA7 to BA10). Repeated infections in 46 cases (82.1%) occurred in the next season, and only one case occurred in the same season (10-day interval). First infections were 33 (63.5%) HRSV-A cases and 19 (36.5%) HRSV-B cases, whereas second infections occurred in 35 (67.3%) HRSV-A cases and 17 (32.7%) HRSV-B cases. Third infections were attributed to 4 (100.0%) HRSV-A cases. Homologous subgroup reinfections were detected in 28 cases, 23 HRSV-A cases and 5 HRSV-B cases (P = 0.005), whereas homologous genotype reinfections were detected only for 5 HRSV-A cases (2GA5 and 3NA2) but not any HRSV-B case. Heterologous subgroup reinfections were detected in 28 cases, 12 cases from HRSV-A-to-HRSV-B reinfections and 16 cases from HRSV-B-to-HRSV-A reinfections. Genotypes NA1 and NA2 had higher numbers of heterologous genotype infections than did other genotypes. Our observations suggest that repeated infections occur more frequently in HRSV-A strains than in HRSV-B strains, and heterologous genotype reinfections occur more frequently than homologous genotype reinfections, especially in the case of the emerging genotypes NA1 and NA2 of HRSV-A strains that circulated in the community during our study period.

New genotypes within respiratory syncytial virus group B genotype BA in Niigata, Japan.

Phylogenetic analysis of respiratory syncytial virus (RSV) group B genotype BA strains from the 2002-2003 to 2009-2010 seasons collected in Niigata, Japan, revealed four distinct clusters, designated new BA genotypes BA7, BA8, BA9, and BA10. These new genotypes were not associated with large outbreaks in the community.

Emerging genotypes of human respiratory syncytial virus subgroup A among patients in Japan.

Human respiratory syncytial virus (HRSV) is a common etiological agent of acute lower respiratory tract disease in infants. We report the molecular epidemiology of HRSV in Niigata, Japan, over six successive seasons (from 2001 to 2007) and the emerging genotypes of HRSV subgroup A (HRSV-A) strains. A total of 488 HRSV samples were obtained from 1,103 screened cases in a pediatric clinic in Niigata. According to the phylogenetic analysis, among the PCR-positive samples, 338 HRSV-A strains clustered into the previously reported genotypes GA5 and GA7 and two novel genotypes, NA1 and NA2, which were genetically close to GA2 strains. One hundred fifty HRSV-B strains clustered into three genotypes, namely, GB3, SAB3, and BA, which has a 60-nucleotide insertion in the second hypervariable region of the G protein. The NA1 strains emerged first, in the 2004-2005 season, and subsequently, the NA2 strain emerged in the 2005-2006 season. Both strains caused large epidemics in the 2005-2006 and 2006-2007 seasons. The average age of children who were infected with NA2 strains was significantly higher than that of those infected with GA5 and the frequency of reinfection by NA2 was the highest among all genotypes, suggesting that this genotype possessed new antigenicity for evading past host immunity. This is the first paper to show a possible correlation between an emerging genotype, NA2, and large outbreaks of HRSV in Japan. Continuing studies to follow up the genetic changes and to clarify the mechanism of reinfection in HRSV are important steps to understand HRSV infections.

Prevalence of human metapneumovirus and influenza virus infections among Japanese children during two successive winters.

BACKGROUND: Human metapneumoviruses (hMPVs) are recognized as a leading cause of respiratory infections in young infants in many countries. The objective of this study was to identify links between hMPV and influenza virus infections among children with influenza-like illness. METHOD: This study was conducted in 2 influenza seasons (2002-2003 and 2003-2004) at 2 pediatric outpatient clinics in Niigata city, Japan. Nasopharyngeal swabs or aspirates were collected from influenza-like illness patients, and hMPV and influenza were detected by reverse transcription-polymerase chain reaction (RT-PCR). A nucleotide sequence of 352 nucleotides segment of the F gene was performed. RESULTS: A total of 765 influenza viruses and 84 hMPV were identified from 1498 nasopharyngeal swabs or aspirates by virus isolation and RT-PCR, respectively. hMPV-positive rates in patients with influenza-like illness were 5.7 and 5.2% in the 2002-2003 and 2003-2004 seasons, respectively. Epidemic curves of influenza and hMPV patients showed similar patterns with peaks in February in 2 influenza seasons. hMPV infections occurred frequently in infants and school children. Approximately 46% of hMPV patients were coinfected with influenza A viruses, but those coinfected cases were not clinically distinct from the others. No coinfection with influenza B viruses was found. Phylogenetic analysis of the hMPV fusion gene sequences revealed that 2 distinct hMPV cocirculated and that completely identical strains in subgroup A were observed over 2 years. CONCLUSIONS: HMPV plays an important pathogenic role in patients with influenza-like illness in winter seasons, often in coinfections with influenza A viruses.

Molecular epidemiology of respiratory syncytial virus infections among children with acute respiratory symptoms in a community over three seasons.

To study the molecular epidemiology of respiratory syncytial virus (RSV) in a community, children with acute respiratory symptoms at a pediatric outpatient clinic in Niigata, Japan, were analyzed over three seasons from November 2001 to July 2004. Of 499 nasopharyngeal aspirate specimens, 185 (37.1%) were RSV positive, and only 8 (4.5%) of 177 patients were shown by the reverse transcription (RT)-PCR method to be reinfected. RSV infection occurred beginning in the early winter, and the rates declined in the spring. The predominant subgroup changed from A to B and returned to A over the three seasons. Phylogenetic analysis also revealed that multiple genotypes cocirculated each year, with genotype GA5 of subgroup A predominating in the 2001-2002 and the 2003-2004 seasons. A new genotype of subgroup B (named BA, according to the nomenclature for viruses) with a 60-nucleotide insertion in the second variable region of the attachment glycoportein protein was predominant as an emerging strain in the 2002-2003 season, but this was not associated with new epidemiological or clinical features, unlike the cases of disease caused by other genotypes in the other seasons. In conclusion, our molecular analysis of RSV confirms that multiple genotypes cocirculate each year and that the genotype predominating may shift with the season. Support for determination of the genotype by RT-PCR as an effective tool for characterization of RSV circulation patterns in the community is provided.

Frequency of amantadine-resistant influenza A viruses during two seasons featuring cocirculation of H1N1 and H3N2.

In two influenza seasons during which H1N1 and H3N2 cocirculated, resistance was more frequent in H3N2 strains than in H1N1 strains after amantadine treatment. Predominant amino acid substitutions in M2 protein occurred at position 31 (serine to asparagine) in H3N2 strains and at position 27 (valine to alanine) in H1N1 strains.