The end of the COVID-19 pandemic in the respiratory disease season of 2022—23 was characterized by an increase in the number of cases, a shift in the classic peaks of morbidity for various infections, and a predominance of influenza and respiratory syncytial virus infection (RSVI). Materials and methods. When compared with the last pandemic season, a later start of the 2023—24 respiratory season was noted with a gradual shift to the usual pre-pandemic period timing of viral morbidity increases. Results. The currently prevailing SARS-CoV-2 Omicron variant has acquired the properties of a common respiratory viral infection, currently all-season, with a mild course, without the need for hospitalization. The number of patients with influenza has decreased and there were no patients with a severe course of this infection. A feature of the first post-pandemic season was the outbreak of mycoplasma infection, which was a reason of large number of pneumonia cases.

Goal. To analyze gene expression in patients with cerebral insufficiency during the critical period and during late convalescence after severe neuroinfection. Materials and methods. The study involved patients with infectious diseases aged from 3 to 17 years, admitted for treatment to the department of resuscitation and intensive care of the Federal State Budgetary Institution DNACIB FMBA of Russia. Whole blood samples were collected before the start of therapy — «Acute period» and during the period of late convalescence after the disease (9, 12, 13 months). RNA sequencing was performed to analyze differential gene expression. Results. Statistically significant differences in expression in the comparison group «Acute period» and «Late convalescence» were detected in 14 genes. Thus, in the «Acute period» group, 12 genes with decreased expression and 2 genes with increased expression were identified: ANGPTL2, encoding angiopoietin-like protein 2 and PCK1 of the phosphoenolpyruvate carboxykinase enzyme. Of the 14 genes, 5 had unknown functions and unidentified orthologues. Conclusion. The authors suggest that increased expression of the ANGPTL2 gene may be the cause of the consequences of hypoxia, which leads to acute cerebral failure during a severe infectious process. Increased expression of PCK1 may indicate increased brain glucose demand during recovery.

Objective. To study the characteristics of severe acute bronchiolitis (AB) caused by hMPV (hMPV-AB). Materials and Methods: This retrospective comparative study included 27 patients aged 2 to 12 months, who were hospitalized from 2021 to 2023 in the Intensive Care Unit (ICU) of the «Kommunarka» Moscow Multidisciplinary Clinical Center. The etiology of AB was determined using polymerase chain reaction. Results. Patients with hMPV-AB had a longer stay in the ICU compared to patients with AB of another etiology (9.0 [5.0; 11.0]; 3,0 [2.0; 4.0] days, p = 0.007). Ratio SpO2/FiO2 was lower in patients with hMPV-AB (190.2 [131.0; 203.3]) compared to patients with AB of another etiology (275.0 [253.0; 340.0], p = 0.001). Rating on the Pediatric Sequential Organ Failure Assessment (pSOFA) was higher in patients with hMPV-AB (5.0 [3.45; 11.0] vs. 1.0 [0.54; 1.93], p = 0.002). One lethal outcome was recorded in the hMPV-AB group. Conclusions. hMPV-AB in children is characterized by a more severe course and requires more intensive treatment compared to AB of other etiologies.

The coronavirus infection is a pressing issue in modern healthcare, yet the characteristics of the SARS-CoV-2 infection course in children with comorbidities remain insufficiently studied. The aim of this study was to evaluate the clinical form, severity, and duration of SARS-CoV-2 virus shedding in pediatric patients with somatic diseases, depending on the comorbid pathology. Materials and Methods. A comprehensive single-center retrospective study was conducted, analyzing 314 medical records of patients hospitalized in the infectious diseases department of the Russian Children’s Clinical Hospital in Moscow over 11 months in 2022. The inclusion criterion was the presence of a laboratory-confirmed COVID-19 diagnosis. Results. Children with comorbidities were found to be predisposed to a more severe course of SARS-CoV-2 infection compared to the pediatric population in general. Children with hematological diseases were at the highest risk of adverse outcomes from COVID-19. Patients with oncological and hematological diseases and primary immunodeficiencies shed the SARS-CoV-2 virus significantly longer than patients with other somatic pathologies. The duration of SARS-CoV-2 RNA detection in patients with severe COVID-19 was significantly longer, which also correlated with the severity of the underlying somatic disease. Conclusion. Children with comorbidities are at risk for a more severe and prolonged course of SARS-CoV-2 infection.

To date, the pathogenesis of COVID-19 associated multisystem inflammatory syndrome (MIS-C) remains unclear. Despite this, it becomes obvious that the pathogenesis of MIS-C is directly related to a certain immune dysregulation, however, a clear understanding of the mechanisms of this dysregulation has not yet been formulated. In order to identify the cytokine profile in patients with MIS-C, spontaneous and stimulated production of certain cytokines in cell culture was identified. Materials and methods. The study was conducted in the following study groups: group 1 — patients with MIS-C (n = 52); group 2 (comparison group) — patients with COVID-19 associated pneumonia (n = 15); group 3 (control group) — conditionally healthy patients (n = 23). The following stimulating agents were used: S58 — recombinant antigen Spike_SARS-Cov-2; NP is a recombinant NP antigen of the coronavirus SARS-CoV-2 and a standard mitogen. Results. Тhe absence of the initially expected hyperproduction of the main pro-inflammatory cytokines (IL-6, IL-8, TNF-α, etc.) was recorded. Statistically significant developments were recorded between patients of the study groups in the spontaneous production of MCP-1, in particular, the indicated indicator was 40010.82 (19698.1; 64812.1); 643.7 (214.6; 1695.4) and 622.7 (214.6; 1068.1), respectively. The indicated spontaneous hyperproduction of MCP-1 in patients with MIS-C allows us to consider as a probable completely new theory of the pathogenesis of MIS-C associated with dysregulation of the type 2 immune response. The presence of statistically significant differences, primarily in the spontaneous production of this cytokine, can apparently be explained by the presence of genetically determined determinants associated with subsequent dysfunction of the Th2 helper immune response, a potential trigger for which is a previous COVID-19 infection. Thus, further study of the immunopathogenesis of COVID-19 associated MIS-C is required.

The article presents current data on the state of the issue of Hepatitis A (HA) in children in the Russian Federation and describes clinical and epidemiologic features of rare cases of severe course of the disease, as well as pathogenetic mechanisms of liver damage mediated by cell immune response. Objective. To identify clinical and epidemiologic features of the modern course of HA and its outcomes in children of Saint Petersburg within the period of 2018— 2023. Materials and methods. The study included 89 children diagnosed with HA, undergoing treatment at the Children's Research and Clinical Center for Infectious Diseases from 2018 to 2023. The analysis of disease progression in this group of patients was presented using clinical-anamnestic, epidemiologic, biochemical, virologic and instrumental data. Results. The analysis of infection sources showed a high frequency of HA infection within the family (44.9 ± 0.8%) and significantly less in childcare facilities and schools (7.9 ± 1.0%). The frequency of children with unidentified sources of infection remained high (47.2 ± 0.7%). One-third of all disease cases were imported from southern regions. Most hospitalized children had icteric HA (64.0 ± 0.6%) of moderate severity (79.8 ± 0.5%). Severe HA was observed in 6 patients (6.7 ± 1.0%). During the study, 17 patients (19.1 ± 0.9%) had a prolonged, complicated course of the disease, including ascites and aplastic anemia (12.6 ± 2.2%). Ascites was found in 4 patients with severe severity and in 5 patients with moderate severity of HA. Conclusions. Currently, there is an upward trend in the incidence of HA in the Russian Federation and Saint Petersburg, especially among schoolchildren (56.2%). A rather high frequency of severe (6.7%) and complicated forms (19.1%) of the disease is observed, and the growth of ascites and aplastic anemia cases in HA draws particular attention.

In the spring 2022, the number of cases of severe acute hepatitis of unknown etiology was unusual increased in Europe. As an immediate response, the World health organization recommended active efforts to identify such cases at the international level. For monitoring of acute hepatitis in Moscow, patients with suspected liver disease were sent to Infectious Diseases Clinical Hospital No. 1. The goal: study of the structure of diseases occurring with liver damage in children hospitalized in 2022. Materials and methods: analysis of medical records of children hospitalized with a diagnosis of hepatitis from May 1 to December 31, 2022. Еpidemiological data (age, gender, parenteral manipulations, contacts with patients, travel abroad), clinical (fever, jaundice, etc.), laboratory parameters were assessed. Results: A total of 164 completed cases of hepatitis in children aged 5 months to 17 years were analyzed. 36 children met the criteria for probable severe acute hepatitis of unknown etiology. Age median was 7 years [2.25;11]. Girls made up more than half (21 (58.3%). Non-infectious genesis was established in 15 (41.6%). The infectious disease was verified in 11 (30.5%), of which adenoviral infection was detected in 2 children. In 9 (25%) children the etiology of hepatitis was not established. Conclusion. Various infectious and non-infectious diseases among hospitalized children lead to a significant increase in liver transaminases. Most acute hepatitis with unspecified etiology proceeded as an acute infectious disease and ended in recovery. The role of adenoviruses in the development of severe hepatitis in children was not confirmed in our study.

Rotavirus infection is one of the leading causes of severe diarrhea in children under five years of age worldwide and contributes significantly to child mortality. The introduction of rotavirus vaccination for epidemic indications into the Russian National Immunization Schedule has not impacted the epidemiological situation due to low vaccination coverage. This article provides a review of studies evaluating the clinical significance of rotavirus infection in the context of mass vaccination, as well as its impact on the circulation of rotavirus genotypes. We have analyzed data on the prevalence of rotavirus, the severity of clinical cases, and changes in the genetic diversity of the virus. It has been noted that vaccination reduces the severity of gastroenteritis; however, over time, changes in circulating viral strains have been observed. Despite the positive effects of vaccination, some countries have reported an increase in the prevalence of other pathogens, such as norovirus and Campylobacter. These findings emphasize the need to continue vaccination efforts and monitor changes in the structure of pathogens responsible for acute intestinal infections to improve preventive measures and control the epidemiological situation.

The incidence of whooping cough is usually higher than the official statistics due to underdiagnosis of the infection, especially in older children. The significant increase in the incidence of measles and whooping cough in recent years has been reflected in the modern problem of mixed infections. We had the opportunity to observe patients with whooping cough combined with measles in a family outbreak in two unvaccinated sisters aged 10 and 13.

Whooping cough is a widespread infectious disease, the manifestations of which vary from nonspecific cough to life-threatening conditions with the development of apnea, hypoxic damage to the central nervous system, and respiratory failure, especially in young children. Against the background of a severe form of whooping cough, hemorrhages of various types can be observed, including in the brain. 
The team of authors describes a clinical case of cerebral impairment in a child under one year of age, which is associated with whooping cough. A day after discharge from the infectious diseases hospital, the child developed a generalized convulsive attack. Clinical, instrumental and objective data allowed us to establish a diagnosis: acute disorder of cerebral and spinal circulation of the hemorrhagic type. Subarachnoid hemorrhage. Severe anemia. Convulsive syndrome. Whooping cough. Subsequently, the development of signs of hydrocephalus was observed over time, with the further formation of multiple cysts and hemiatrophy of the right hemisphere of the brain.

Neonatal hypernatremia is a condition in which the concentration of sodium in the blood of a newborn child exceeds 145 mmol/l. The causes of this pathology may be kidney disease, endocrine problems, transdermal water loss, iatrogenic sodium overload. In addition, dehydration due to insufficient breastfeeding remains one of the important factors leading to hypernatremia. Clinical signs include: significant weight loss, decreased skin turgor, anxiety, fever, seizures, and direct hyperbilirubinemia. The main complications of this condition are intracranial hemorrhages, venous sinus thrombosis and acute renal tubule necrosis. Infusion therapy and adequate oral nutrition are used to correct hypernatremia. The article presents a clinical case of hypernatremia in a newborn child caused by hypogalactyly in the mother. The purpose of the demonstration is to raise awareness and alertness among pediatricians and neonatologists about the possibility of this problem.

Rabies is a dangerous viral disease characterized by severe damage to the brain and spinal cord. A clinical case of rabies in a 14-year-old teenager with a fatal outcome is presented. After the child's contact with a hedgehog was registered, post-exposure prophylaxis of rabies was not administered to the child. The complexity of timely diagnosis of rabies and the need for emergency prophylaxis of rabies after contact with wild animals are demonstrated.