Prevalence and clinical impact of mono- and co-infections with endemic coronaviruses 229E, OC43, NL63, and HKU-1 during the COVID-19 pandemic.

Introduction: Endemic human coronaviruses (eHCoVs) are found worldwide and usually result in mild to moderate upper respiratory tract infections. They can lead to more severe illnesses such as croup, bronchiolitis, and pneumonia in vulnerable populations. During the coronavirus disease 2019 (COVID-19) pandemic, information on HCoV prevalence and incidence and clinical impact of co-infections of HCoV with SARS-CoV-2 was lacking. Objectives: Thus, this study aimed to determine the prevalence and clinical significance of infections caused by eHCoVs during the COVID-19 pandemic in Bulgaria. Methods: From January 2021 to December 2022, nasopharyngeal swabs of patients with acute upper or lower respiratory tract infections were tested for 17 respiratory viruses using multiplex real-time polymerase chain reaction assays. The clinical data and laboratory parameters of patients infected with respiratory viruses were analysed. Results: Of the 1375 patients screened, 24 (1.7 %) were positive for HCoVs, and 197 (14.3 %) were positive for eight other seasonal respiratory viruses. Five (0.7 %) of 740 patients positive for SARS-CoV-2 were co-infected with eHCoVs. Co-infected patients had a mean C-reactive protein level of 198.5 ± 2.12 mg/mL and a mean oxygen saturation of 82 ± 2.8 mmHg, while those in patients co-infected with SARS-CoV-2 and other respiratory viruses were 61.8 mg/mL and 92.8 ± 4.6 mmHg, respectively (p < 0.05). Pneumonia was diagnosed in 63.3 % of patients with HCoV infection and 6 % of patients positive for other seasonal respiratory viruses (p < 0.05). Patients with SARS-CoV-2 mono-infection stayed in hospital for an average of 5.8 ± 3.7 days, whereas the average hospital stay of patients with eHCoV and SARS-CoV-2 co-infection was 9 ± 1.4 days (p < 0.05). Conclusion: These findings indicate the low prevalence of eHCoVs and low co-infection rate between eHCoVs and SARS-CoV-2 during the COVID-19 pandemic in Bulgaria. Despite their low incidence, such mixed infections can cause severe signs that require oxygen therapy and longer hospital stays, underlining the need for targeted testing of severe COVID-19 cases to identify potential co-infections.

Clinical Case of Parvovirus B19 Infection in Pregnant Woman with Β-Thalassemia in Bulgaria.

A pregnant 30-year-old female in the 34th gestational week was admitted at University "Maichin Dom" Hospital prior to childbirth. The patient is diagnosed with ß-thalassemia. During laboratory screening hemoglobin of 98 g/L was established. Blood smear shows mild microcytic hypochromic anemia: RBC 5.15 x 1012/L, HGB 98 g/L, MCV 65.8 fL, MCH 19.4 pg, MCHC 295 g/L. Serum iron concentration is 12.9 µmol/L and ferritin 17.5 µg/L. For the delivery process cesium was considered. Two days after procedure a rash presented on face, hands and breasts. Although the mother was positive for parvovirus B19 infection, the baby was negative. This was confirmed by se-rological and molecular investigations. We discovered only the mother's B19V IgG antibodies in the newborn. In connection to the main disease, namely ß-thalassemia, acute virus infection could cause aplastic crisis. After consultation with a hematologist, serum hepcidin concentration (an iron homeostasis regulator) was quantified: 19.4 µg/L. ELISA test was used to prove B19V IgM antibodies in the mother. PCR analysis shows the presence of B19V DNA. During infection, inflammatory cytokines increase hepcidin secretion, leading to iron deposition into cells.

Predominance of influenza B/Yamagata lineage viruses in Bulgaria during the 2017/2018 season.

In this study, we investigated the antigenic and genetic characteristics of influenza viruses circulating in Bulgaria during the 2017/2018 season. The detection and typing/subtyping of influenza viruses were performed using real-time RT-PCR. Results of antigenic characterisation, phylogenetic and amino acid sequence analyses of representative influenza strains are presented. The season was characterised by the predominance of B/Yamagata viruses, accounting for 77% of detected influenza viruses, followed by A(H1N1)pdm09 (17%), B/Victoria (3.7%) and A(H3N2) (2.4%). The sequenced B/Yamagata, B/Victoria, A(H1N1)pdm09 and A(H3N2) viruses belonged to the genetic groups 3, 1A, 6B.1 and 3C.2a1, respectively. Amino acid analysis of B/Yamagata isolates revealed the presence of three changes in haemagglutinin (HA), eight changes in neuraminidase (NA) and a number of substitutions in internal proteins compared with the B/Phucket/3073/2013 vaccine virus. Despite the amino acid changes, B/Yamagata viruses remained antigenically related to the vaccine strain. B/Victoria isolates fell into a group of viruses with double deletion (Δ162-163) in HA1. Substitutions in HA and NA sequences of B/Victoria, A(H1N1)pdm09 and A(H3N2) viruses were also identified compared with the vaccine strains, including in antigenic sites. The results of this study confirm the genetic variability of circulating influenza viruses and the need for continual antigenic and molecular surveillance.

[NEW APPROACH IN DIAGNOSTIC ALGORITHM OF AN INFECTIOUS AGENTS (PARVOVIRUS B19 AND CHLAMYDIA TRACHOMATIS) INVOLVED IN THE DEVELOPMENT OF PATHOLOGICAL PREGNANCY].

UNLABELLED: Viral infections during pregnancy, along with some form of accompanying pregnancy diseases such as diabetes, cardiovascular, gastrointestinal, kidney and others, are a major cause of arising complications and mortality of mother and fetus. AIM: To improved the laboratory diagnostic approach in the study of women with pathological pregnancy, including improve treatment and prognostic character of the outcome of pregnancy, with the inclusion of two infectious agent parvovirus B19 and Chlamydia trachomatis. To determine types of anemia in pregnant women with parvovirus B19 and Chlamydia trachomatis infection and to select the correct therapeutic approach. MATERIALS AND METHODS: A total 36 serum samples from pregnant women with anemia (n = 22), nonimmune hydrops fetalis (n = 8) and fetal ascites (n = 6) were tested. The study included three newborns (n = 3), tested on the occasion of a possible maternal-fetal infections. The serological (indirect ELISA tests) and molecular (B19V-PCR test) methods were used. In anemic pregnant women were evaluated iron homeostasis parameters with CLIA, AAS and NEPH methods. RESULTS: In 6/36 (16.66%) patients B19V-IgM positive result was detected. Among the study patients with anemia, non-immune hydrops fetalis and fetal ascites incidence of proven B19V-IgM antibodies was 18.18% (4/22), 12.5% (1/8) and 16.66% (1/6), respectively. Protective B19-IgG antibodies in 25/39 (64.10%) samples were found. A positive PCR signal was showed in all patients with positive B19V-IgM, and 1 patient with anemia and positive B19V-IgG result. The three newborns were positive for B19V-IgG antibodies (maternal) and negative for acute viral infection. Present Chlamydia trachomatis infection in 6/36 (16.66%) and past infection in 5/36 (13.89%) patients was demonstrated. The anemia was evaluated as iron-deficiency according to low hepcidin levels 2.54 ± 0.4 µg/I compared to pregnant control group which included women without anemia 25.9 ± 2.8 µg/I. CONCLUSION: In view of the varied transmission B19V and the wide range of complications arising as a result of chlamydia, screening for these viral agents of pregnant women and women of childbearing age is an important approach for monitoring of pregnancy.