Resurgence of respiratory syncytial virus with dominance of RSV-B during the 2022-2023 season.

Background: Respiratory syncytial virus (RSV) is a common cause of upper and lower respiratory tract infections. This study aimed to explore the prevalence of respiratory syncytial virus (RSV) and other respiratory viruses in Bulgaria, characterize the genetic diversity of RSV strains, and perform amino acid sequence analyses of RSV surface and internal proteins. Methods: Clinical and epidemiological data and nasopharyngeal swabs were prospectively collected from patients with acute respiratory infections between October 2020 and May 2023. Real-time PCR for 13 respiratory viruses, whole-genome sequencing, phylogenetic, and amino acid analyses were performed. Results: This study included three epidemic seasons (2020-2021, 2021-2022, and 2022-2023) from week 40 of the previous year to week 20 of the following year. Of the 3,047 patients examined, 1,813 (59.5%) tested positive for at least one viral respiratory pathogen. RSV was the second most detected virus (10.9%) after SARS-CoV-2 (22%). Coinfections between RSV and other respiratory viruses were detected in 68 cases, including 14 with SARS-CoV-2. After two seasons of low circulation, RSV activity increased significantly during the 2022-2023 season. The detection rates of RSV were 3.2, 6.6, and 13.7% in the first, second, and third seasons, respectively. RSV was the most common virus found in children under 5 years old with bronchiolitis (40%) and pneumonia (24.5%). RSV-B drove the 2022-2023 epidemic. Phylogenetic analysis indicated that the sequenced RSV-B strains belonged to the GB5.0.5a and GB5.0.6a genotypes. Amino acid substitutions in the surface and internal proteins, including the F protein antigenic sites were identified compared to the BA prototype strain. Conclusion: This study revealed a strong resurgence of RSV in the autumn of 2022 after the lifting of anti-COVID-19 measures, the leading role of RSV as a causative agent of serious respiratory illnesses in early childhood, and relatively low genetic diversity in circulating RSV strains.

Clinical significance and role of coinfections with respiratory pathogens among individuals with confirmed severe acute respiratory syndrome coronavirus-2 infection.

Introduction: This study aimed to determine the prevalence, viral profile, and clinical features of coinfections with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and other respiratory viruses. Methods: Nasopharyngeal samples and clinical data of 221 hospitalized patients and 21 outpatients were collected and analyzed. Real-time reverse transcription-polymerase chain reaction was used to detect SARS-CoV-2, influenza virus, respiratory syncytial virus (RSV), human metapneumovirus (HMPV), parainfluenza virus (PIV) 1,2,3, rhinovirus (RV), adenovirus (AdV), bocaviruses (BoV), and seasonal coronaviruses (OC43, 229E, NL63, and HKU1). Viral load was determined by capillary electrophoresis. Results: From November 2020 to mid-March 2022, 242 SARS-CoV-2 positive patients were tested for seasonal respiratory viruses, and 24 (9.9%) cases of coinfections were detected. The distribution of viruses involved in cases of coinfections were as follows: HMPV (n = 6; 25%), RSV (n = 4;16.7%), AdV (n = 4; 16.7%), BoV (n = 4; 16.7%), PIV3 (n = 2; 8.3%), influenza A (H3N2; n = 2; 8.3%), RV (n = 1; 4.62%), and RV+BoV (n = 1; 4.62%). The proportion of detected coinfections with SARS-CoV-2 was highest in children aged 0-5 years (59%), followed by those >65 years (33%). In specimens with detected coinfection, the viral load of influenza was higher than that of SARS-CoV-2, and the mean viral load of SARS-CoV-2 was higher than that of the other respiratory viruses. C-reactive protein (CRP) and lymphocytes count in co-infected patients >65 years of age were on average higher than in children <16 years of age (mean CRP of 161.8 ± 133.1 mg/L; 19.7 ± 3.09% vs. mean 6.9 ± 8.9 mg/L, 0.9 ± 3.1%; p < 0.01). Patients >65 years of age co-infected with SARS-CoV-2 and other respiratory viruses had longer hospital stays than those <16 years of age (mean 9 ± 3.96 days vs. 5.44 ± 1.89 days; p = 0.025). The combination of AdV and SARS-CoV-2 is fatal for patients aged >65 years. Conclusion: In patients aged >65 years, coinfection with SARS CoV-2 and other respiratory viruses, together with concomitant diseases, causes worsening of the clinical picture and complications, and can be fatal. Screening of patients with SARS CoV-2 for other respiratory viruses is needed to select appropriate treatments and prevent a fatal outcome of the disease.

COVID-19 and gastrointestinal injury: a brief systematic review and data from Bulgaria.

In December 2019, a new Coronavirus (SARS-CoV-2) emerged in China, causing the pandemic disease COVID-19. The clinical presentation is variable, but the predominant symptoms are those of the upper respiratory tract. AIM: The aim of the current study is to describe the incidence and type of the gastrointestinal injury (GI) in COVID-19, as well as their prognostic value. MATERIALS AND METHODS: We conducted a coincidental search on this topic in PubMed, Web of Science and EMBASE. We also followed a group of 31 Bulgarian COVID-19 patients throughout the course of their disease and analyzed their symptoms (catarrhal and other) and outcome. RESULTS: The publications concerning our survey followed a total of 1509 COVID-19 patients. In the Bulgarian cohort, only 14 from the 31 patients were laboratory-confirmed COVID-19 cases. Approximately 1/3 of the infected individuals presented with GI. In some patients this was the first, or only, symptom of the disease. It was also indicative of a more severe disease course. CONCLUSION: GI may be an important symptom and prognostic factor in COVID-19. Therefore, patients with acute gastrointestinal symptoms must be actively tested for SARS-CoV-2.

Viral pathogens associated with acute lower respiratory tract infections in children younger than 5 years of age in Bulgaria.

Acute lower respiratory infections (ALRIs) are a leading cause of morbidity and hospital admissions in children. This study aimed to determine the viral etiology of these infections in children aged < 5 years during three successive epidemic seasons in Bulgaria. Nasopharyngeal and throat specimens were collected from children with bronchiolitis and pneumonia during the 2015/2016, 2016/2017, and 2017/2018 seasons. The viral etiology was determined by individual real-time PCR assays against 11 respiratory viruses. Of the 515 children examined, 402 (78.1%) were positive for at least one virus. Co-infections with two and three viruses were found in 64 (15.9%) of the infected children. Respiratory syncytial virus (RSV) was the predominant pathogen (37.5%), followed by rhinoviruses (13.8%), metapneumovirus (9.1%), adenoviruses (7%), bocaviruses (7%), influenza A(H1N1)pdm09 (4.9%), A(H3N2) (4.3%), type B (4.1%), and parainfluenza viruses 1/2/3 (2.9%). RSV-B were more prevalent than RSV-A during the three seasons. At least one respiratory virus was identified in 82.6% and 70.1% of the children with bronchiolitis and pneumonia, respectively. Respiratory viruses, especially RSV, are principal pathogens of ALRIs in children aged < 5 years. Diagnostic testing for respiratory viruses using molecular methods may lead to the reduced use of antibiotics and may assist in measures to control infection.

Blood-Brain Barrier and Intrathecal Immune Response in patients with neuroinfections.

Cerebrospinal fluid/serum albumin ratio is one of the most informative parameters for blood-brain barrier (BBB) integrity in cases of central nervous system (CNS) infectious diseases. Normally, CNS albumin concentration is a function of diffusion processes along with CSF drainage and resorption. In pathological processes CSF albumin levels are dependent only on the rate of CSF drainage resulting in non-linear reciprocal changes of albumin quotient (Qalb). IgG, IgA and IgM concentrations both in CSF and serum can be compared to Qalb, thus determining the intrathecal immune response. The aim of the study was to detect BBB permeability impairment and the intrathecal immune response in patients with CNS infections with various etiologies. CSF/serum ratios were calculated and related to IgG IgA and IgM concentrations in CSF and blood serum. The results were integrated and presented by Reibergrams. The results demonstrated typical patterns which prove albumin to be the main modulator of protein dynamics and at the same time explicates the complex pathophysiological mechanisms involved in BBB disruption and intrathecal immune response in CNS infections. The diagnostic model presented in our study seeks to explain the observations of meningitis and meningoencephalitis pathophysiology and points out the mandatory cooperation between clinicians and laboratory for accurate diagnosis and proper treatment.