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Radostina Alexandrova,1 Ilia Tsachev,2 Plamen Kirov,1 Abedulkadir Abudalleh,1 Hristo Hristov,1 Tanya Zhivkova,1 Lora Dyakova,3 Magdalena Baymakova4 1Department of Pathology, Institute of Experimental Morphology, Pathology and Anthropology with Museum, Bulgarian Academy of Sciences, Sofia, Bulgaria; 2Department of Microbiology, Infectious and Parasitic Diseases, Faculty of Veterinary Medicine, Trakia University, Stara Zagora, Bulgaria; 3Department of Synaptic Signaling and Communication, Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria; 4Department of Infectious Diseases, Military Medical Academy, Sofia, BulgariaCorrespondence: Magdalena Baymakova, Department of Infectious Diseases, Military Medical Academy, Sofia, Bulgaria, Tel +359-882-28-50-87, Email dr.baymakova@gmail.comAbstract: Hepatitis E virus (HEV) is a single-stranded positive-sense RNA virus that belongs to Hepeviridae family. HEV is the most common cause of acute viral hepatitis worldwide. According to the World Health Organization (WHO), there are estimated 20 million HEV infections worldwide every year, leading to estimated 3.3 million symptomatic cases of HEV infection. The WHO estimates that HEV infection caused approximately 44,000 deaths in 2015, which represents 3.3% of mortality rates due to viral hepatitis. In low-income (LI) countries and lower-middle-income (LMI) countries, HEV is a waterborne infection induced by HEV genotype (gt) 1 and HEV gt 2 that cause large outbreaks and affect young individuals with a high mortality rate in pregnant women from South Asian countries and patients with liver diseases. HEV gt 3, HEV gt 4, and HEV gt 7 are responsible for sporadic infections with zoonotic transmission mainly through the consumption of raw or undercooked meat from different animals. Acute HEV infection is relatively asymptomatic or mild clinical form, in rare cases the disease can be moderate/severe clinical forms and result in fulminant hepatitis or acute liver failure (ALF). Furthermore, HEV infection is associated with extrahepatic manifestations, including renal and neurological clinical signs and symptoms. Pregnant women, infants, older people, immunocompromised individuals, patients with comorbidities, and workers who come into close contact with HEV-infected animals are recognized as major risk groups for severe clinical form of HEV infection and fatal outcome. Chronic HEV infection can occur in immunocompromised individuals with the possibility of progression to cirrhosis.Keywords: acute and chronic infection, cancer, cirrhosis, hepatitis E virus, HEV, HIV, solid organ transplants

Magdalena Baymakova,1 Metodi Kunchev,2 Raynichka Mihaylova-Garnizova,1 Anelia Zasheva,1 Kamen Plochev,1 Todor Kundurzhiev,3 Ilia Tsachev4 1Department of Infectious Diseases, Military Medical Academy, Sofia, Bulgaria; 2Department of Virology, Military Medical Academy, Sofia, Bulgaria; 3Department of Occupational Medicine, Faculty of Public Health, Medical University, Sofia, Bulgaria; 4Department of Microbiology, Infectious and Parasitic Diseases, Faculty of Veterinary Medicine, Trakia University, Stara Zagora, BulgariaCorrespondence: Magdalena Baymakova, Department of Infectious Diseases, Military Medical Academy, Sofia, Bulgaria, Tel +359-882-28-50-87, Email dr.baymakova@gmail.comIntroduction: The acute viral hepatitis was one of the most common conditions in daily clinical practice varying in different parts of the world. The aim of the present study was to perform a comparative analysis on clinical characteristics among patients with acute hepatitis A virus (HAV) infection and patients with acute hepatitis E virus (HEV) infection admitted to the Military Medical Academy (MMA), Sofia, Bulgaria.Methods: A retrospective study was performed at MMA, between 1 January 2016 and 31 December 2021. The etiological diagnosis was confirmed by enzyme-linked immunosorbent assay (ELISA) HAV/HEV IgM serology assays.Results: The current survey included 231 patients with mean age 45.11 ± 16.08 years (95% confidence interval: 43.04– 47.19). According to the case definition, inclusion and exclusion criteria, persons were divided into two groups: patients with acute HAV infection (68.4%; 158/231) and patients with acute HEV infection (31.6%; 73/231). Males with HEV had 3.091 times the odds of comorbidity “hypertension” than males with HAV (p = 0.032). There were almost equal odds of increased ALT (odds ratio = 0.999; p = 0.003) in men with HEV and men with HAV. Females with HEV had 5.161 times the odds of comorbidity “hypertension” compared with females with HAV (p = 0.049). We found almost equal odds for elevated ALT in women with HEV and women with HAV (OR = 0.999; p = 0.025). In the non-elderly group (< 60-year-old), HEV individuals had 4.544 and 10.560 times the odds of comorbidities “hypertension” and “cardiovascular diseases” compared with HAV patients (p < 0.05). We found almost equal odds for elevated ALT in HEV patients and HAV participants (OR = 0.998; p = 0.002).Conclusion: The results from the current study may support the physicians daily care for patients with acute HAV and acute HEV.Keywords: Bulgaria, clinical characteristics, hepatitis A virus, HAV, hepatitis E virus, HEV, single-center study

We present a case of 68-year-old female with four months history of fever, fatigue, and weight loss. She was classified as case of fever of unknown origin. The physical examination was normal, the laboratory tests showed anemia, elevation of C-reactive protein, erythrocyte sedimentation rate and fibrinogen. The diagnosis was unclear and 18F-FDG PET/CT was performed. Images showed high glucose uptake in the wall of the ascending and descending aorta, in the walls of the subclavian arteries, abdominal aorta and proximal part of both iliac arteries. The diagnosis of GCA appeared most likely and steroid treatment was initiated. After the therapy, clinical signs disappeared, laboratory parameters normalized and follow-up 18F-FDG PET/CT demonstrated lack of glucose uptake in the vessels' walls. We observed remission. 18F-FDG PET/CT offers a possibility for early detection of inflammation in the vessels and could be used for assessment of therapy response. Performing this nuclear imaging method in a clinical setting, where there is suspicion of large-vessel vasculitis is of great benefit for the final outcome. [ABSTRACT FROM AUTHOR]

OBJECTIVE Fever of unknown origin (FUO) is a puzzling condition. The causes of FUO can be classified in five groups: infections, neoplasia, non-infectious inflammatory diseases, miscellaneous and undiagnosed causes. Vector-borne diseases are important emerging illnesses globally. The aim of this study was to estimate their prevalence and to describe the clinical and laboratory features of patients with vector-borne diseases presenting as FUO. METHOD Retrospective analysis was made of the characteristics of 78 patients with febrile syndrome investigated over a period of 4 years at the Department of Infectious Diseases of the Military Medical Academy (Sofia, Bulgaria). All patients underwent a thorough medical history, physical examination and laboratory investigations and the final diagnosis was based on clinical, epidemiological and laboratory data. RESULTS The modified Petersdorf-Beeson criteria for FUO were fulfilled by 54 of the patients. A definitive diagnosis was made in 45 and infectious diseases were established in 32 (59.3%) cases. Vector-borne diseases were identified in 10 patients. The diagnosis was determined in 7 as Rickettsioses (R. conorii 2/10 and C. burnetii 5/10), co-infection with C. burnetii and C. pneumoniae in one, and Lyme disease in two patients. CONCLUSIONS The leading cause of FUO among the Bulgarian population is infectious diseases, in agreement with other published data from South-East Europe. Among infections, the illnesses caused by arthropod-transmitted disease are not rare: 31.3% of all infections. Explanations for these results include the geographical location, climate and level of economic development. [ABSTRACT FROM AUTHOR]

Introduction: Bulgaria joined European Union (EU) on 1 January 2007. Since the accession all regulations, directives, decisions, recommendations, and opinions of the European Parliament, the Council of the European Union, and the European Commission are being implemented.

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Background/Aim. Mediterranean spotted fever (MSF) belongs to Rickettsioses, the Spotted fever group (SFG). The causal agent is Rickettsia conorii conorii and the transmission to humans occurs through dog tick Rhipicephalus sanguineus bites. The aim of this study was to describe clinical and laboratory characteristics in patients with severe form of Mediterranean spotted fever admitted to Bulgarian university hospital in endemic region. Methods. A retrospective study was conducted at Stara Zagora University Hospital (Southeastern Bulgaria) between April 2015 and August 2016. During the analyzed period, 58 cases had clinical and laboratory data for MSF. Serological tests were applied for the etiological diagnosis. MSF-specific immunoglobulin (IgM) and IgG antibodies were detected in serum by indirect immunoenzyme assay (ELISA IgG/IgM, Vircell, Spain) – R. conorii ELISA IgG sensitivity 85%, specificity 100% and R. conorii ELISA IgM sensitivity 94%, specificity 95%. Statistical analysis was made by MS Excel 2007 and SPSS Statistics, version 19.0. Results. Eighteen patients presented as severe forms. The predominant gender of them were males (78%) and 22% were females. The median age of the analyzed group was 55 years (range: 14– 78 years). Ten patients developed hepatic disorder while 4 had neurological signs. Laboratory data showed thrombocytopenia in 15 patients, mean value of platelet (PLT) count for the whole group was 108.6 ± 53.8 × 109/L. Liver enzymes were elevated with mean value of aspartate aminotransferase (AST) 161.4 ± 90.1 IU/L and alanine aminotransferase (ALT) 163.9 ± 81.5 IU/L. Acute phase reactant as C-reactive protein (CRP) had mean value of 140.3 mg/L (range: 9–230 mg/L). Kidney function was impaired in some cases; the mean value of creatinine for the studied group was 134.7 μmol/L (range: 78–313 μmol/L) and mean value of urea was 9.6 mmol/L (range: 4.2–27.4 mmol/L). Conclusion. Bulgaria is an endemic area for tick-borne diseases. Cases of MSF are reported annually. Severe forms of MSF are not rare. Typical clinical and laboratory markers for severity should be actively searched for. Early diagnosis and proper treatment is the key to avoid complications and enable patient recovery.

We present here the first five human cases with tularemia from two regions in South Bulgaria in which there had been no previous report of the infection. The cases occurred over a period of 8 months (December 2014 - August 2015). They were treated at the Department of Infectious Diseases in Stara Zagora University Hospital, Bulgaria. We present the clinical, epidemiological and laboratory data for four men and one woman (age range 52 to 73 years). Three men were hunters, four patients took part in handling, preparing/skinning and cooking the game animals. One man marked agricultural work and contact with straw stems. After a mean incubation period of 4.8±1.4 days ulcers appeared, followed by local painful lymphadenitis. All patients presented with liver enlargement and elevation in acute phase reactants. The etiological diagnosis was made by tube agglutination test in all cases, PCR positive result was found in one. The administered antibacterial treatment was a combination of aminoglycosides and 4-quinolones with the outcome being favorable for all patients. The current report suggests presence of Francisella tularensis in South Bulgaria.

Introduction. Hepatitis E is one of the leading clinical manifestations of acute viral hepatitis in developing countries. In industrialized countries, during the past several years, sporadic “autochthonous” cases of HEV infection have been increased. Objective. The aim of this study was to analyze the epidemiological, clinical and laboratory features of HEV infection among patients hospitalized at the Department of Infectious Diseases in Military Medical Academy, Sofia, Bulgaria. Methods. A retrospective study of 806 cases of acute viral hepatitis was performed at the Department of Infectious Diseases in Military Medical Academy, Sofia, Bulgaria, between December 2004 and September 2012. The etiological diagnosis was established by ELISA. The statistical analysis was performed using Excel 2007 (Microsoft, Redmond, Washington, USA) and SPSS Statistics 19.0 (IBM Corp., Armonk, New York, USA). Results. Specific reaction to anti-HEV-IgM and anti-HEV-IgG antibodies were detected in 20 (2.48%) of 806 patients. The most observed clinical presentations were jaundice (85%), fatigue (85%), anorexia (65%), abdominal discomfort (55%) and fever (40%). The mean values of aspartate transaminase and alanine transaminase were 521 IU/l and 881 IU/l, respectively. The cholestasis was slight, marked with mean values of gamma-glutamyl transferase and alkaline phosphatase, respectively 418 IU/l and 486 IU/l. Conclusion. We report twenty autochthonous sporadic cases of acute infection with HEV. The zoonotic etiology of the virus as well as the foodborne transmission of the infection is discussed. We found that aging and pre-existing underlying diseases are risk factors for a severe course of the HEV infection.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), a pneumonia with extremely heterogeneous clinical presentation, ranging from asymptomatic to severely ill patients. Previous studies have reported links between the presence of host genetic variants and the outcome of the COVID-19 infection. In our study, we used whole exome sequencing in a cohort of 444 SARS-CoV-2 patients, admitted to hospital in the period October-2020-April-2022, to search for associations between rare pathogenic/potentially pathogenic variants and COVID-19 progression. We used gene prioritization-based analysis in genes that have been reported by host genetic studies. Although we did not identify correlation between the presence of rare pathogenic variants and COVID-19 outcome, in critically ill patients we detected known mutations in a number of genes associated with severe disease related to cardiovascular disease, primary ciliary dyskinesia, cystic fibrosis, DNA damage repair response, coagulation, primary immune disorder, hemoglobin subunit β, and others. Additionally, we report 93 novel pathogenic variants found in severely infected patients who required intubation or died. A network analysis showed main component, consisting of 13 highly interconnected genes related to epithelial cilium. In conclusion, we have detected rare pathogenic host variants that may have influenced the COVID-19 outcome in Bulgarian patients., (© 2024. The Author(s).)

Background: Fever of unknown origin (FUO) in developing countries is an important dilemma and further research is needed to elucidate the infectious causes of FUO., Methods: A multi-center study for infectious causes of FUO in lower middle-income countries (LMIC) and low-income countries (LIC) was conducted between January 1, 2018 and January 1, 2023. In total, 15 participating centers from seven different countries provided the data, which were collected through the Infectious Diseases-International Research Initiative platform. Only adult patients with confirmed infection as the cause of FUO were included in the study. The severity parameters were quick Sequential Organ Failure Assessment (qSOFA) ≥2, intensive care unit (ICU) admission, vasopressor use, and invasive mechanical ventilation (IMV)., Results: A total of 160 patients with infectious FUO were included in the study. Overall, 148 (92.5%) patients had community-acquired infections and 12 (7.5%) had hospital-acquired infections. The most common infectious syndromes were tuberculosis (TB) ( n =27, 16.9%), infective endocarditis ( n =25, 15.6%), malaria ( n =21, 13.1%), brucellosis ( n =15, 9.4%), and typhoid fever ( n =9, 5.6%). Plasmodium falciparum, Mycobacterium tuberculosis , Brucellae, Staphylococcus aureus, Salmonella typhi , and Rickettsiae were the leading infectious agents in this study. A total of 56 (35.0%) cases had invasive procedures for diagnosis. The mean qSOFA score was 0.76±0.94 {median (interquartile range [IQR]): 0 (0-1)}. ICU admission ( n =26, 16.2%), vasopressor use ( n =14, 8.8%), and IMV ( n =10, 6.3%) were not rare. Overall, 38 (23.8%) patients had at least one of the severity parameters. The mortality rate was 15 (9.4%), and the mortality was attributable to the infection causing FUO in 12 (7.5%) patients., Conclusions: In LMIC and LIC, tuberculosis and cardiac infections were the most severe and the leading infections causing FUO., (© 2023 The Author(s).)

In recent years, hepatitis E virus (HEV) infection has been found to be widespread among different animal species worldwide. In Bulgaria, high HEV seropositivity was found among pigs (60.3%), wild boars (40.8%), and East Balkan swine (82.5%). The aim of the present study was to establish the seroprevalence of HEV among dogs, cats, horses, cattle, sheep, and goats in Bulgaria. In total, 720 serum samples from six animal species were randomly collected: dogs-90 samples; cats-90; horses-180; cattle-180; sheep-90; and goats-90. The serum samples were collected from seven districts of the country: Burgas, Kardzhali, Pazardzhik, Plovdiv, Sliven, Smolyan, and Stara Zagora. The animal serum samples were tested for HEV antibodies using the commercial Wantai HEV-Ab ELISA kit (Beijing, China). The overall HEV seroprevalence among different animal species from Bulgaria was as follows: dogs-21.1%; cats-17.7%; horses-8.3%; cattle-7.7%; sheep-32.2%; and goats-24.4%. We found the lowest overall HEV seropositivity in Plovdiv district (6.2%; 4/64; p = 0.203) and Smolyan district (8.8%; 4/45; p = 0.129), vs. the highest in Pazardzhik district (21.6%; 29/134; p = 0.024) and Burgas district (28.8%; 26/90; p = 0.062). To the best of our knowledge, this is the first serological evidence of HEV infection in dogs, cats, horses, cattle, sheep, and goats from Bulgaria. We found high HEV seropositivity in small ruminants (sheep and goats), moderate seropositivity in pets (dogs and cats), and a low level of seropositivity in large animals (horses and cattle). Previous Bulgarian studies and the results of this research show that HEV infection is widespread among animals in our country. In this regard, the Bulgarian health authorities must carry out increased surveillance and control of HEV infection among animals in Bulgaria.

Hepatitis E virus (HEV) is one of the leading causes of acute viral hepatitis. Transmission of HEV mainly occurs via the fecal-oral route (ingesting contaminated water or food) or by contact with infected animals and their raw meat products. Some animals, such as pigs, wild boars, sheep, goats, rabbits, camels, rats, etc., are natural reservoirs of HEV, which places people in close contact with them at increased risk of HEV disease. Although hepatitis E is a self-limiting infection, it could also lead to severe illness, particularly among pregnant women, or chronic infection in immunocompromised people. A growing number of studies point out that HEV can be classified as a re-emerging virus in developed countries. Preventative efforts are needed to reduce the incidence of acute and chronic hepatitis E in non-endemic and endemic countries. There is a recombinant HEV vaccine, but it is approved for use and commercially available only in China and Pakistan. However, further studies are needed to demonstrate the necessity of applying a preventive vaccine and to create conditions for reducing the spread of HEV. This review emphasizes the hepatitis E virus and its importance for public health in Europe, the methods of virus transmission and treatment, and summarizes the latest studies on HEV vaccine development.

Fever of unknown origin (FUO) is a serious challenge for physicians. The aim of the present study was to consider epidemiology and dynamics of FUO in countries with different economic development. The data of FUO patients hospitalized/followed between 1st July 2016 and 1st July 2021 were collected retrospectively and submitted from referral centers in 21 countries through ID-IRI clinical research platform. The countries were categorized into developing (low-income (LI) and lower middle-income (LMI) economies) and developed countries (upper middle-income (UMI) and high-income (HI) economies). This research included 788 patients. FUO diagnoses were as follows: infections (51.6%; n = 407), neoplasms (11.4%, n = 90), collagen vascular disorders (9.3%, n = 73), undiagnosed (20.1%, n = 158), miscellaneous diseases (7.7%, n = 60). The most common infections were tuberculosis (n = 45, 5.7%), brucellosis (n = 39, 4.9%), rickettsiosis (n = 23, 2.9%), HIV infection (n = 20, 2.5%), and typhoid fever (n = 13, 1.6%). Cardiovascular infections (n = 56, 7.1%) were the most common infectious syndromes. Only collagen vascular disorders were reported significantly more from developed countries (RR = 2.00, 95% CI: 1.19-3.38). FUO had similar characteristics in LI/LMI and UMI/HI countries including the portion of undiagnosed cases (OR, 95% CI; 0.87 (0.65-1.15)), death attributed to FUO (RR = 0.87, 95% CI: 0.65-1.15, p-value = 0.3355), and the mean duration until diagnosis (p = 0.9663). Various aspects of FUO cannot be determined by the economic development solely. Other development indices can be considered in future analyses. Physicians in different countries should be equally prepared for FUO patients., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Immune memory to SARS-CoV-2 is key for establishing herd immunity and limiting the spread of the virus. The duration and qualities of T-cell-mediated protection in the settings of constantly evolving pathogens remain an open question. We conducted a cross-sectional study of SARS-CoV-2-specific CD4+ and CD8+ T-cell responses at several time points over 18 months (30-750 days) post mild/moderate infection with the aim to identify suitable methods and biomarkers for evaluation of long-term T-cell memory in peripheral blood. Included were 107 samples from 95 donors infected during the periods 03/2020-07/2021 and 09/2021-03/2022, coinciding with the prevalence of B.1.1.7 (alpha) and B.1.617.2 (delta) variants in Bulgaria. SARS-CoV-2-specific IFNγ+ T cells were measured in ELISpot in parallel with flow cytometry detection of AIM+ total and stem cell-like memory (T SCM ) CD4+ and CD8+ T cells after in vitro stimulation with peptide pools corresponding to the original and delta variants. We show that, unlike IFNγ+ T cells, AIM+ virus-specific CD4+ and CD8+ T SCM are more adequate markers of T cell memory, even beyond 18 months post-infection. In the settings of circulating and evolving viruses, CD8+ T SCM is remarkably stable, back-differentiated into effectors, and delivers immediate protection, regardless of the initial priming strain.

Human activity has a direct influence on the climate on our planet. In recent decades, the greater part of the scientific community has united around the concept of Global Warming (GW). This process highly impacts the geographical distribution of mosquitoes and Mosquito-Borne Diseases (MBD). The examined scientific publications show that Africa, especially sub-Saharan countries were and still hot spot of MBD globally. The economic, social, and environmental conditions prevailing in most African countries have effectively contributed to the spread of MBD. The current situation is very worrying, and it will get even more complicated as GW gets worse. In this regard, health systems in developing countries will have serious difficulties in health policies and public health activities to control the spread on MBD. Therefore, the governments of African countries should do more to combat MBD. However, a part of the responsibility lies with the international community, especially countries that contribute to GW. In conclusion, the analysis of the scientific literature showed that with increasing importance of GW leads to an increase in the prevalence of MBD., Competing Interests: The authors declare no competing interests., (Copyright: Bachir Khezzani et al.)

Background: The aim of this research was to perform a seroepidemiological survey of hepatitis E virus (HEV) by an alternative method-serological establishment of the virus from pig liver transudate. This is the first such research in Bulgaria. Moreover, no studies have been conducted on HEV in pig liver in our country. Materials and Methods: A total of 90 liver samples from healthy pigs were collected from slaughterhouses in three parts of the country (Sofia, Lovech, and Stara Zagora districts). An equal number of samples ( n  = 30) were obtained from each district. Results: The overall HEV seropositivity was 67.7% of all 90 tested pig liver transudate samples; in Sofia district 20.0%, in Lovech district 90.0%, and in Stara Zagora district 93.3%. Conclusion: These data are similar to our previous serological studies for HEV in serum samples from industrial pigs, wild boars, and East Balkan swine. In this regard, testing the liver transudate could be a fine alternative method for seroepidemiological survey on HEV in swine.

In Bulgaria, vaccination coverage against the SARS-CoV-2 virus is low. The reasons for this fact are many and varied. The aim of the present study was to establish what the attitudes towards the COVID-19 vaccination process are among students from various specialties from several Bulgarian universities. In this research, 600 students participated, divided into two groups: Doctor of Medicine (MD) students (n = 300) and non-MD students, i.e., students of specialties, such as mathematics, engineering, finance and economics, law, human sciences, etc. (n = 300). Each respondent completed a questionnaire which was divided into three parts with closed questions. The mean age of all students was 21.19 ± 1.87 years (95% CI: 20.48−21.90). The female sex dominated among the analyzed participants (sex ratio: female/male = 1/0.85). Nearly 62% (371/600) of individuals declared that they have been COVID-19 vaccinated with at least one dose (p < 0.001). Overall, 33% of the participants sought information on vaccines from video sharing platforms and 36.0% (216/600) from social media platforms. From the conducted multivariable logistic regression the odds of vaccination against COVID-19 were 6.225 times higher in individuals with a positive attitude towards these vaccines than in people with a negative attitude towards them (p < 0.001). We have found that those students who trust the international health organizations had an OR of 2.365 (p = 0.004) to be SARS-CoV-2 vaccinated. We estimated that the odds of vaccination against SARS-CoV-2 among children were 4.794 times higher in parents (students) who had been vaccinated than in non-vaccinated parents (students) (p < 0.001). Our results could support the national public health organizations, the national educational/scientific systems, and the management of Bulgarian universities in making future decisions about the field of COVID-19 control and prevention.

The hepatitis C virus (HCV)-related bovine hepacivirus (BovHepV) can cause acute as well as persistent infections in cattle. The true clinical relevance of the virus is not yet known. As reliable antibody detection methods are lacking and prevalence studies have only been conducted in cattle and few countries to date, the true distribution, genetic diversity, and host range is probably greatly underestimated. In this study, we applied several RT-PCR methods and a nano-luciferase-based immunoprecipitation system (LIPS) assay to analyze bovine serum samples from Bulgaria as well as wild ruminant sera from Germany and the Czech Republic. Using these methods, BovHepV infections were confirmed in Bulgarian cattle, with viral genomes detected in 6.9% and serological reactions against the BovHepV NS3 helicase domain in 10% of bovine serum samples. Genetic analysis demonstrated co-circulation of highly diverse BovHepV strains in Bulgarian cattle, and three novel BovHepV subtypes within the genotype 1 could be defined. Furthermore, application of a nested RT-PCR led to the first description of a BovHepV variant (genotype 2) in a wild ruminant species. The results of this study significantly enhance our knowledge of BovHepV distribution, genetic diversity, and host range.

Introduction: Dysentery is an infectious clinical syndrome which can cause high morbidity and mortality, especially in developing countries. This research highlights the epidemiological features of dysentery in Lemghaier province, Algeria., Methods: A retrospective study of the incidence rates of dysentery in Lemghaier province, Algeria and overall for the whole country for the period from January 2001 to December 2018 was carried out. On a local level data were provided by the Directorate of Health and Population of El-Oued province, Algeria. At the national level data were provided by the National Public Health Institute, Algeria., Results: An overall number of 1,786 cases of dysentery were notified, with an incidence rate of 58.5 cases per 100,000 population (mean±SD: 58.54±47.20; 95% CI: 36.73-80.35). The high incidence rate was reported in autumn and summer, respectively, with 23.4 and 20.1 cases per 100,000 population. The high incidence rate observed in the persons aged 20-44 years with 76.4 cases per 100,000 population. Females were more likely to have dysentery than males, respectively, with 63.6 against 53.7 cases per 100,000 population. The highest incidence rate was reported in Lemghaier municipality (capital of the province) with 176.9 cases per 100,000 population., Conclusions: The results from this research showed high incidence rates of dysentery in Lemghaier province, Algeria. Тhis fact is a serious reason for national public health organizations to take adequate and timely measures to reduce the incidence rates of dysentery in this part of the country., Competing Interests: Conflicts of interest: All authors – none to declare., (GERMS.)

Information on hepatitis E virus (HEV) strains circulating in animal reservoirs in Bulgaria is currently lacking. Herein, by screening HEV seropositive sera obtained from Bulgarian swine and wild boars, viral RNA was detected at high prevalence rate (28.2%) in industrial pigs. Sequence analysis of the partial polymerase (RdRp) region revealed the highest genetic correlation with HEVs of genotype (Gt) 3 identified in French and Dutch patients. For three such strains, a 700-bp fragment of the open reading frame 2 gene was generated. On phylogenetic analysis, the Bulgarian strains clustered tightly (93.8-98.3% nt) with human and animal HEVs classified within the Gt3 subtype c.

The purpose of the present study was to investigate pigs in Northern Bulgaria for serological evidence of hepatitis E virus (HEV). Sera from 225 individuals from three industrial farms were tested for anti‑HEV IgG antibodies. The overall HEV seroprevalence was 36% (81/225); weaners 6.8% (5/74); fattening pigs 38.7% (29/75) and in sows 61.8% (47/76). Compared to weaners, HEV positivity was higher in fattening pigs and sows: OR = 8.70 (95% CI: 3.14‑24.12) and OR = 22.37 (95% CI: 8.07‑61.96), respectively. These data confirm that HEV is endemic in pigs throughout Bulgaria, and can be a Public Health problem due to the transmission of HЕV to humans through the consumption of pork meat and pork products.

Scientific evidence indicates that hepatitis E virus (HEV) infection is a zoonotic disease. Domestic pigs and wild boars are the main animal reservoir for HEV worldwide. The aim of this study was to analyze the seroprevalence of HEV infection among wild boars in western Bulgaria. Serum samples from 240 wild boars from two regions of the country (northwestern and southwestern) were tested for anti-HEV Immunoglobulin G (IgG) antibodies. The overall HEV seroprevalence was 40.8% (98/240); northwestern region 40.0% (48/120); southwestern region 41.7% (50/120). HEV seropositivity in the southwestern region was higher than in the northwestern region: odds ratio = 1.071 (95% confidence interval: 0.640-1.793). This research provided the first seroprevalence study to HEV in wild boars from western Bulgaria.

Hepatitis E virus (HEV) infection is widespread among domestic pigs, industrial swine, and wild boars in Bulgaria. The aim of the current research was to present the HEV seroprevalence among blood donors in Bulgaria. In the present study, 555 blood donors (479 males and 76 females) were enrolled from five districts in the country (Shumen, Pleven, Stara Zagora, Plovdiv, and Sofia districts). All blood samples were tested for anti-HEV IgG using the recom Well HEV IgG ELISA test (Mikrogen GmbH, Neuried, Germany). Each participating donor completed a short, structured, and specific questionnaire to document data on the current study. Anti-HEV IgG positive results were detected in 144 (25.9%) blood donors, including 129 (26.9%) males and 15 (19.7%) females. The established HEV seropositivity was 28.8% (23/80) in Shumen district, 23.2% (22/95) in Pleven district, 27.1% (38/140) in Stara Zagora district, 27.5% (44/160) in Plovdiv district, and 21.3% (17/80) in Sofia district. A high HEV seroprevalence was found for persons who declared that they were general hunters (48.7%; 19/39; p = 0.001) and hunters of wild boars (51.6%; 16/31; p = 0.001). We present the first seroprevalence rates of HEV infection in blood donors from Bulgaria. The results of our research showed high HEV seropositivity among blood donors.

Introduction: SARS-CoV-2 infection is spreading around the world, including countries from Southeastern Europe. The purpose of the study was to present the clinical manifestations of COVID-19 patients admitted to the Military Medical Academy, Sofia, Bulgaria. Materials and Methods: A retrospective study was conducted for a period of 3 months from March 2020 to June 2020 on this infection in our hospital. All participants were laboratory confirmed cases of COVID-19. RT-PCR was performed for etiological diagnosis. The hospitalized patients were divided into two groups on admission, that is, nonsevere and severe. Results: One hundred thirty-eight COVID-19 patients were hospitalized and analyzed during the study period. The mean age was 52.9 years. Male was the dominant sex (sex ratio: male/female = 1/0.6). The leading clinical signs were fever, fatigue, cough, and headache. On comparative analysis of both groups (nonsevere and severe) was measured significant elevation of white blood cells (odds ratio [OR] = 1.238; p value = 0.006), C-reactive protein (OR = 1.021; p  < 0.001), creatinine (OR = 1.037; p  < 0.001), aspartate aminotransferase (OR = 1.014; p  = 0.040), lactate dehydrogenase (OR = 1.004; p  < 0.001), ferritin (OR = 1.002; p  < 0.001), fibrinogen (OR = 2.028; p  < 0.001), and d-dimer (OR = 2.162; p  = 0.002) in severe group than in nonsevere group. Interleukin 6 was tested in 17.4% of patients and high value was found-38.6 pg/mL (95% confidence interval: 16.5-60.7). Conclusion: The first Bulgarian retrospective study of COVID-19 hospitalized patients was presented. Older age, male sex, comorbidity, and signs of dyspnea and nausea were estimated as higher risk factors for severe form. Abnormality in inflammatory markers was associated with poor progression of the illness.

The East Balkan swine ( Sus scrofa ) is the only aboriginal pig breed in Bulgaria, and it is indigenous to the eastern part of the country. The aim of the present study was to investigate East Balkan swine (EBS) in Bulgaria for serological evidence of hepatitis E virus (HEV). Sera from 171 swine from two parts of the country (northeastern and southeastern) were tested for anti-HEV IgG antibodies. The overall HEV seroprevalence was 82.5% (141/171), and for weaners it was 77.2% (44/57), for fattening pigs 79.0% (45/57), and for adults 91.2% (52/57). HEV positivity was higher in fattening pigs and adults compared to weaners: OR = 1.108 (95% CI: 0.456-2.692) and OR = 3.073 (95% CI: 1.016-9.294), respectively. This study provides the first evidence of exposure to HEV in EBS from Bulgaria.

The aim of the present study was to investigate the prevalence rates of the feline tick-borne pathogens (FTBPs)- Borrelia burgdorferi , Ehrlichia canis , and Anaplasma phagocytophilum in stray cats from Southern Bulgaria. Serum antibodies were used to estimate the prevalence of exposure to FTBPs from blood swabs. Of the 100 cat samples tested with in-clinic assay SNAP 4Dx Plus, the overall FTBP seroprevalence was 3% (3/100); with B. burgdorferi -1% (1/100) and E. canis -2% (2/100). This study provides the first evidence of exposure to B. burgdorferi and E. canis in cats from Bulgaria.

Hepatitis E virus (HEV) has been isolated from humans and several animals' species. During the last years, the knowledge of HEV infection dramatically changed and enriched. The aim of this study was to estimate the seroprevalence of HEV in industrial pigs in different districts of Southern Bulgaria. Three hundred sixty swine serum samples were tested for anti-HEV IgG antibodies. The samples were collected from four industrial farms from three districts of Southern Bulgaria. HEV-specific antibodies in porcine serum were detected by enzyme-linked immunosorbent assay (PrioCHECK HEV Ab porcine). The overall HEV seroprevalence was 60.3%. The seropositivity varied widely depending on age groups and investigated farms. The overall prevalence in weaners was 25%, in fattening pigs 75.8%, and in group of sows was found the highest HEV positivity of 80%. The occurrence of HEV positivity in sows and fattening pigs presented odds ratio (OR) = 17.200 (95% confidence interval [CI]: 8.8-33.7) and OR = 11.342 (95% CI: 6.1-21.0), respectively, compared to weaners. The study indicated that HEV is widespread in industrial farms in Bulgaria and presented high seroprevalence in pigs. The results found that HEV seropositivity showed age dependency. The National Health Authorities should raise awareness of HEV and its zoonotic potential.