Search

The aim of this study was to analyze the seroprevalence of West Nile virus (WNV) among equids in Bulgaria, confirm the results of a competitive ELISA versus the virus neutralization test (VNT) and investigate some predisposing factors for WNV seropositivity. A total of 378 serum samples from 15 provinces in northern and southern Bulgaria were tested. The samples originated from 314 horses and 64 donkeys, 135 males and 243 females, aged from 1 to 30 years. IgG and IgM antibodies against WNV protein E were detected by ELISA. ELISA-positive samples were additionally tested via VNT for WNV and Usutu virus. Thirty-five samples were WNV-positive by ELISA (9.26% [CI = 6.45-12.88]), of which 15 were confirmed by VNT; hence, the seroprevalence was 3.97% (CI = 2.22-6.55). No virus-neutralizing antibodies to Usutu virus were detected among the 35 WNV-ELISA-positive equids in Bulgaria. When compared with VNT, ELISA showed 100.0% sensitivity and 94.5% specificity. A statistical analysis showed that the risk factors associated with WNV seropositivity were the region ( p < 0.0001), altitude of the locality ( p < 0.0001), type of housing ( p < 0.0001) and breed ( p = 0.0365). The results of the study demonstrate, albeit indirectly, that WNV circulates among equids in northern and southern Bulgaria, indicating that they could be suitable sentinel animals for predicting human cases and determining the risk in these areas or regions of the country.

Members of the Papillomaviridae family account for 27.9-30% of all infectious agents associated with human cancer. The aim of our study was to investigate the presence of high-risk HPV (human papilloma virus) genotypes in patients with periodontitis and a pronounced clinical picture. To achieve this goal, after proving the bacterial etiology of periodontitis, the samples positive for bacteria were examined for the presence of HPV. The genotype of HPV is also determined in samples with the presence of the virus proven by PCR (polymerase chain reaction). All positive tests for bacteria associated with the development of periodontitis indicated the presence of HPV. There was a statistically significant difference in HPV positive results between the periodontitis positive target group and the control group. The higher presence of high-risk HPV genotypes in the target group, which was also positive for the presence of periodontitis-causing bacteria, has been proven. A statistically significant relationship was established between the presence of periodontitis-causing bacteria and high-risk strains of HPV. The most common HPV genotype that tests positive for bacteria associated with the development of periodontitis is HPV58.

The aim of this study was to verify whether the human DR-ELISA for the detection of anti-SARS-CoV-2 antibodies can be applied in cats, and to assess the risk factors that determine the spread of the virus among the cat population in Bulgaria. The study included 92 serum samples collected from 68 domestic and 24 stray cats aged from 3 months to 20 years of age in the period of January-June 2021. The samples originated from three regions in Bulgaria and from three places of inhabitance. DR-ELISA based on peroxidase-labeled SARS-CoV-2 N protein was employed to detect IgA, IgG and IgM antibodies in the samples. Subsequently, the results were compared with a commercially available multi-species ELISA kit. There was high seroprevalence (83.33%) in stray cats and 41.18% in domestic cats, confirmed by the human and veterinary ELISA kit. The positive cases in the regional cities were 42.86%, in small towns 50% and in villages 78.26%. Cats under 7 years had a five times higher risk than those over 7 years ( p = 0.001). The risk was seven times higher for stray cats than for domestic cats ( p = 0.001). In addition, the results indicate that the risk was the highest for cats in villages ( p = 0.006) compared to cats in other places of inhabitance. This study demonstrates that human DR-ELISA may be successfully applied to monitor the circulation of SARS-CoV-2 in cats and other susceptible species. Cats might serve as sentinel animals for tracking the virus in nature and in inhabited areas (strays) and to discover asymptomatic cases in humans/owners.

The purpose of this review is to describe the contents of Pb and Zn in sediments and hydrobionts as ecological markers for the pollution assessment of freshwater objects in Bulgaria, and the data are compared with other countries and regions. Symmetry was found regarding the levels of Zn in the sediment of the Ovcharitsa and Zhrebchevo dams, which were twice the MAC for arable land (Regulation № 3 of Bulgarian legislation). Symmetry was also observed between the results for Zn and Pb in the studied sediments, and the "favorites" in terms of content were the samples from Zhrebchevo Dam and, especially, from Ovcharitsa Dam. Asymmetry was established in the accumulation of Zn in the livers of carps inhabiting Topolnitsa Dam in comparison with these in Ovcharitsa Dam. A similar asymmetry was observed for lead. The analysis of the muscles and livers of the studied fish showed an asymmetry in the accumulation of zinc, and this process was more intense in the liver. Symmetry was found in the accumulation of Pb in the liver and muscle tissues of the carp from the studied water bodies.

The aim of this study was to assess the resistance of bovine mastitis S. aureus isolates from farms in Bulgaria to different classes of chemotherapeutic drugs by comparison of some phenotypic and genotypic methods by means of Cohen's kappa statistics. The study comprised 546 milk samples from subclinical and clinical mastitis at 14 farms from 9 districts in the country. A total of 92 Staphylococcus aureus strains were isolated from tested samples and identified by nuc PCR. The results demonstrated high levels of resistance to sulfadimethoxine (87%), followed by resistance to penicillin (33.7%), erythromycin (13%), streptomycin (8.7%), tetracycline (6.5%) and gentamicin (1.1%). The comparison of both phenotypic tests with respect to 9 antimicrobials revealed strong agreement with kappa coefficient 0.836. An almost complete agreement was evidenced between phenotypic resistance to penicillin and blaZ gene presence, to methicillin with mecA gene, to tetracycline with tet genes, but the agreement between erythromycin resistance and erm genes presence was moderate. This study was the first to demonstrate discrepancy between the behaviour to cefoxitin in the disk diffusion test and oxacillin in the MIC test for an isolate shown to carry the mecA gene in the subsequent genetic analysis. Considering the detected discrepancies for some of isolates, an integral evaluation through phenotypic and molecular methods for monitoring of antimicrobial resistance of Staphylococcus aureus is recommended.

SARS-CoV-2 emerged in 2019 and found diagnostic laboratories unprepared worldwide. To meet the need for timely and accurate virus detection, laboratories used rapid Ag tests and PCR kits based on costly multi-channel real-time techniques. This study aimed to develop a conventional nested PCR based on the SARS-CoV-2 N gene, validate it against some approved assays, and apply it to samples from six cats with respiratory symptoms obtained in early 2020 during the first COVID-19 wave in humans in Bulgaria. The nested PCR technique showed 100% sensitivity and specificity; it could detect extracted SARS-CoV-2 RNA at concentrations as low as 0.015 ng/μL. The results identified the six tested cat samples as positive. Sequence analysis performed in two of them confirmed this. The presented technique is reliable, easy to implement and inexpensive, and can be successful in strategies for the prevention and control of SARS-CoV-2 in humans, cats and other susceptible species.