Classical fever of unknown origin in 21 countries with different economic development: an international ID-IRI study.

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.

Seroprevalence of Anaplasma phagocytophilum, Ehrlichia spp. and Borrelia burgdorferi infections in horses: first report from Northern Bulgaria - Short communication.

Lyme borreliosis, granulocytic anaplasmosis and monocytic ehrlichiosis are well studied in humans and dogs. In horses, these diseases are not widely investigated and limited information is available about their occurrence. The purpose of this study was to present the first ELISA-based report on the seroprevalence of Anaplasma phagocytophilum, Ehrlichia spp. and Borrelia burgdorferi in horses from Northern Bulgaria. A total of 192 horses were investigated from three regions in Northern Bulgaria (Northwestern, North-Central and Northeastern Bulgaria). All equine sera were tested for A. phagocytophilum, Ehrlichia spp. and B. burgdorferi antibodies by a commercial rapid ELISA test. Antibodies against A. phagocytophilum were found in all the three regions at a mean frequency of 12% (23/192), ranging from 9.38 to 15.63% by region. Antibodies against Ehrlichia spp. were found in horses from one region (Northeastern) at a rate of 0.5% (1/192). Anti-B. burgdorferi antibodies were detected in all the three regions with a mean frequency of 15.1% (29/192), ranging from 14.06 to 17.19% by region. A co-exposure to A. phagocytophilum and B. burgdorferi was observed in 6.3% of the cases (12/192). This is the first report on the natural exposure of horses to these bacteria (A. phagocytophilum, Ehrlichia spp. and B. burgdorferi) in Northern Bulgaria.

WEST NILE VIRUS INFECTION WITH NEUROLOGICAL DISORDERS: A CASE REPORT AND A BRIEF REVIEW OF THE SITUATION IN BULGARIA.

A case of a 66-year-old man with West Nile neuroinvassive disease manifested with fever, weakness, fatigue, consciousness disorders and underlying diabetes mellitus type 2 and cardiovascular diseases is presented. Laboratory data showed elevated erythrocyte sedimentation rate and fibrinogen. Serological tests revealed West Nile virus specific antibodies of class IgM and IgG in serum. West Nile virus RNA was detected in urine sample. Supportive therapy was applied.

Clinical Characteristics of Ulceroglandular Tularemia in Two Bulgarian Regions, 2014-2015: a Report of Five Cases.

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.

Hepatitis E Virus (HEV) Infection Among Immunocompromised Individuals: A Brief Narrative Review.

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.

Infectious causes of fever of unknown origin in developing countries: An international ID-IRI study.

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.

Hepatitis E Virus (HEV) Infection among Humans and Animals: Epidemiology, Clinical Characteristics, Treatment, and Prevention.

The public health significance of hepatitis E is very important [...].

Global warming and mosquito-borne diseases in Africa: a narrative review.

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.

Comparative Analysis on Clinical Characteristics Among Patients with Acute Hepatitis A Virus (HAV) and Patients with Acute Hepatitis E Virus (HEV): A Single-Center Retrospective Study from Bulgaria.

Introduction: 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.

First Insight into the Seroepidemiology of Hepatitis E Virus (HEV) in Dogs, Cats, Horses, Cattle, Sheep, and Goats from Bulgaria.

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.

Virus-Specific Stem Cell Memory CD8+ T Cells May Indicate a Long-Term Protection against Evolving SARS-CoV-2.

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 (TSCM) 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+ TSCM are more adequate markers of T cell memory, even beyond 18 months post-infection. In the settings of circulating and evolving viruses, CD8+ TSCM is remarkably stable, back-differentiated into effectors, and delivers immediate protection, regardless of the initial priming strain.

The Re-Emergence of Hepatitis E Virus in Europe and Vaccine Development.

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.

Serological Searching for Hepatitis E Virus Infection Among Pig Liver Transudate from Bulgaria: An Alternative Method for Seroepidemiological Survey.

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.

Incidence rates of dysentery among humans in Lemghaier province, Algeria.

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.

Students' Attitudes toward COVID-19 Vaccination: An Inter-University Study from Bulgaria.

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.

Expanded Diversity and Host Range of Bovine Hepacivirus-Genomic and Serological Evidence in Domestic and Wild Ruminant Species.

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.

Seroprevalence of Hepatitis E Virus Infection among Blood Donors in 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 recomWell 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.

Seroprevalence of Hepatitis E Virus Infection Among Wild Boars in Western Bulgaria.

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.

Serological evidence of hepatitis E virus infection in pigs from Northern Bulgaria.

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 anti­HEV 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: 3.14­24.12) and OR = 22.37 (95% CI: 8.07­61.96), 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.