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Primary varicella zoster virus (VZV) infection can cause varicella (chicken pox), which is generally a mild, self-limiting disease; however, VZV infection can also rarely lead to serious complications, such as [...]

To elucidate the seroprevalence and rate of asymptomatic infection with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) in Japanese children, serological analysis was performed using serum samples collected from March 2020 to February 2023. A total of 1493 serum samples were collected during the first study period (March 2020 to February 2021). None of the serum samples was positive for SARS‐CoV‐2 antibody. In the second period (March 2021 to February 2022), seven of the 1055 patients (0.7%) experienced SARS‐CoV‐2 infection. The third period (March 2022 to February 2023) was divided into three terms: from March to June 30, 2022; from July to October 2022; and from November 2022 to February 2023. The seroprevalence gradually increased throughout this period, with rates of 6.0%, 18.6%, and 30.4% in the three terms, respectively. Pediatric cases of asymptomatic SARS‐CoV‐2 infection occurred after the surge of Omicron variants. Since none of the SARS‐CoV‐2 antibody‐positive patients had a previous history of coronavirus disease 2019, the seroprevalence rate in this study may represent the rate of asymptomatic infection. [ABSTRACT FROM AUTHOR]

Nonpharmaceutical interventions (NPIs) to control COVID‐19 have decreased the incidence of many pediatric infectious diseases. The epidemiology of β‐ and γ‐herpesvirus infections might have been affected by NPIs. The aim of this study was to elucidate changes in trends in β‐ and γ‐herpesvirus infections and complex febrile seizures (cFS) of viral etiology before and during the COVID‐19 pandemic. Between April 2017 and March 2021, febrile children aged ≤5 years were enrolled. Detection of EBV, CMV, HHV‐6B, and HHV‐7 DNA in serum was performed using real‐time PCR. The epidemiology of viral infections and cFS were compared between the prepandemic and pandemic periods. During the observation period, 1432 serum samples were collected. The mean number of febrile children decreased during the pandemic period, but the number of patients with HHV‐6B infection increased from 35 (9.3% of all febrile children) per year before the pandemic to 43 (15.5%) during the pandemic. The change in the proportion of patients with primary HHV‐6B infection was 6.50% (95% confidence interval [CI], 2.05%–11.3%; p = 0.0047). The mean number of patients with cFS decreased during the pandemic period, but the number of patients with HHV‐6B–associated cFS was stable throughout the observation period. Therefore, the change in proportion of patients with cFS caused by primary HHV‐6B infection was 49.5% (95% CI, 12.2%–60.5%; p = 0.0048). The disease burden of primary HHV‐6B infection among patients in the emergency room remained unchanged, with a significant increase in the relative proportion after the COVID‐19 pandemic began. [ABSTRACT FROM AUTHOR]

Background: Human herpesvirus 6 (HHV-6) can be genetically transmitted from parent to child as inherited chromosomally integrated HHV-6 (iciHHV-6). HHV-6 reactivation occurs in pregnant women with iciHHV-6. We found no sex differences in the frequency of index cases with iciHHV-6 but inheritance from the father was more common. We evaluated the association between iciHHV-6 status and spontaneous abortion.Methods: iciHHV-6 was confirmed by high viral DNA copy numbers in whole blood and somatic cells. The origin of integrated viral genome, paternal or maternal, was examined using the same method. The pregnancy history of 23 mothers in families with iciHHV-6 and 285 mothers in families without iciHHV-6 was abstracted.Results: Of 23 iciHHV-6 index cases, 8 mothers and 15 fathers had iciHHV-6. Spontaneous abortion rates in mothers with and mothers without/fathers with iciHHV-6 and mothers in families without iciHHV-6 were 27.6%, 10.3%, and 14.8%, respectively (P = .012). Mothers with iciHHV-6 (odds ratio [OR], 6.41; 95% confidence interval [CI], 1.10-37.4) and maternal age at the most recent pregnancy ≥40 years (OR, 3.91; 95% CI, 1.30-11.8) were associated with 2 or more spontaneous abortions.Conclusions: Mothers with iciHHV-6 is a risk factor for spontaneous abortion. [ABSTRACT FROM AUTHOR]

Pediatric cases of the coronavirus disease 2019 (COVID‐19) are generally mild or asymptomatic, and are usually detected by virological examination following close contact with COVID‐19 patients, often the children's parents. The detailed clinical features and virological data of pediatric patients with COVID‐19, particularly young infants, remain unclear. Here, the clinical and virological characteristics of four children with COVID‐19 including two young infants were investigated. One‐ and 4‐month‐old boys with COVID‐19 were both asymptomatic, and seroconversion was demonstrated. These findings suggest that even young infants can mount an immune response against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), despite having weaker immune defenses than adolescents and adults. Three‐year‐old boy, who was SARS‐CoV‐2‐negative, was admitted to the same room as his SARS‐CoV‐2‐positive father due to the lack of caregivers. Although he was asymptomatic, he had seroconverted to SARS‐CoV‐2. Eleven‐year‐old boy, who was sibling of the 3‐year‐old boy, was also SARS‐CoV‐2‐negative. He was isolated in his own room and did not seroconvert. If young children are SARS‐CoV‐2 negative, they should be isolated from their SARS‐CoV‐2‐positive parents. This may be difficult in practice, if parents with COVID‐19 are the only available caregivers. In such situations, the most appropriate measures should be taken for each patient. [ABSTRACT FROM AUTHOR]

Immunocompetent sisters with chromosomally integrated human herpesvirus 6A (HHV-6A) transiently excreted HHV-6B genome in their saliva. They did not have past histories of exanthema subitum but had antibodies against HHV-6A and HHV-6B. This suggests that endogenous HHV-6A may modify the clinical features of HHV-6B coinfection. [ABSTRACT FROM AUTHOR]

Varicella‐zoster virus (VZV) reactivation from the enteric nervous system can cause ileus (Ogilvie's syndrome) in adult patients. Since no pediatric cases have been described, we sought to retrospectively analyze VZV reactivation in pediatric hematology‐oncology patients to determine whether VZV infection including subclinical VZV reactivation can induce gastrointestinal complications such as Ogilvie's syndrome. Thirty‐five patients who received chemotherapy at our institution between September 2013 and June 2018 were included. Serum samples were collected weekly during hospitalization and every 3 months during outpatient maintenance chemotherapy. A real‐time polymerase chain reaction assay was used to measure VZV DNA load in serum. The clinical features of patients with VZV infection were retrospectively analyzed. Of 1165 serum samples, 7 (0.6%) were positive for VZV DNA. VZV DNA was detected in 3 of 35 patients. In patient A, VZV DNA was detected during two episodes. The first episode involved varicella‐like eruptions caused by the Oka VZV vaccine strain. The second episode involved herpes zoster (HZ) caused by the same strain. Patients B and C had a clinical course that was typical for HZ caused by wild‐type VZV. No gastrointestinal symptoms were observed at the time of VZV infection in these three patients. VZV DNA was not detected in any other samples. No pediatric cases with Ogilvie's syndrome caused by VZV reactivation were demonstrated in this cohort. Additionally, no subclinical VZV reactivation was found in this cohort. Further study is needed to elucidate the precise incidence of pediatric Ogilvie's syndrome caused by VZV reactivation. Highlights: Pediatric cases with Ogilvie's syndrome caused by VZV reactivation may be rare.Detection of VZV DNA is serum samples by real‐time PCR is reliable marker for typical herpes zoster.Other suitable samples must be found to monitor subclinical VZV reactivation by real‐time PCR. [ABSTRACT FROM AUTHOR]