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.

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.

Clinical aspects of hantavirus infections in Bulgaria.

BACKGROUND: Hantaviruses cause two distinct human diseases: hemorrhagic fever with renal syndrome (HFRS) in Asia and Europe and hantavirus pulmonary syndrome (HPS) in America. In Europe, mainly Puumala, Dobrava and Seoul viruses cause HFRS. A total of 23 cases of HFRS were detected in Bulgaria over a 2­year period 2013-2014. The aim of the study was to present epidemiology, clinical manifestations and laboratory findings of these patients. METHODS: Patients with HFRS were diagnosed using PCR, ELISA and immunoblotting tests. RESULTS: Dobrava-Belgrade virus (DOBV) was revealed as etiological agent in 16 (69.6%) patients and Puumala virus (PUUV) in 7 (30.4%) patients. All 23 patients were men aged 22-66 years of which 6 (26.1%) patients originated from regions in northern and western Bulgaria previously thought to be non-endemic. Patients with HFRS, despite the infecting hantavirus, manifested acute renal failure, asthenia and less pronounced hemorrhagic syndrome. Patients with DOBV infection were much more likely to present with arthromyalgia, severe headache, severe to moderately severe asthenoadynamia, abdominal pain, vomiting, hypotension, nervous system disorders as well as kidney enlargement, leucopenia and higher levels of blood creatinine, requiring hemodialysis procedures more often and for a longer period of time than patients with PUUV infection. CONCLUSIONS: The present report describes for the first time comparative analysis of epidemiological features, clinical manifestations and laboratory findings of DOBV and PUUV infections in Bulgaria.

[The advantages of dynamic evaluation of measurement quality in clinical diagnostic laboratory].

The national standard of laboratory quality control is based on a assumption about normal distribution of random error. The data of procedure of quality control get from analyzer Flexor XL during three months period were examined. The distributions of random error were non-Gauss ones in almost half of all examined tests by reason of both abnormal asymmetry and excess. To prevent possible clinical mistakes the actual level of quality is to be evaluated using dynamic values of bias, variation coefficient and o-metrics based on simple consecutive means. The most appropriate time of averaging consisted about 10 days and had no dependencies of type of test. The actual standard cab y easily improved taking into account the discovered advantages and simplicity of proposed approach.

[New sorbents for industrial gas marks with a visual reading of their depletion]. / Novi sorbenti za promishleni protivogazi s vizualno otchitane na iztoshtavaneto im.

The current status of problems, referrable to the use of industrial gas masks, is reviewed, with special reference to the type of sorbent to be used, the pathways of gas mask modernization in respect of the sorbents used, and the modern trends in adsorption cartridge manufacturing; decrease of weight, alleviated construction, adjustment to serve definite toxico-chemical agent, use of ion-exchange resins and hemosorbents. Aspects are discussed for producing sorbents, permitting visual registration of filter mass exhaustion, i.e. sorbents wtih alternating color in the process of sorption, with the purpose of increasing gas mask security and efficiency. The physico-chemical parameters of reference hemosorbent samples with alternating color in the process of sorption were compared with those of widely used sorbents - active carbon (specially processed and crude) and ion-exchange resins: relative dynamics, aktivity protection time, weight, mass activity, etc. Inferences are drawn from which one may see, that these new hemosorbents are highly perspektive, and their industrial acceptance is justifiable.