Viral hepatitis, particularly hepatitis B and C, are diseases with worldwide distribution that present a significant public health problem. Seroprevalence studies allow assessment of the extent of the disease burden, the identification of populations at risk and the monitoring trends over time. A multi-center seroprevalence study, carried out in Bulgaria (covering the five largest cities - Sofia, Plovdiv, Varna, Pleven, and Stara Zagora) in 1999-2000 estimated a crude seroprevalence rate of 3.9% for HBsAg and 1.3% for anti-HCV. A decade later, comparable rates were observed in a study including 865 outpatients consulting a clinical laboratory in Plovdiv, the second largest administrative region in Bulgaria. The crude seroprevalence rate measured for hepatitis B (HBsAg) was 3.9%. The HBsAg prevalence rate in individuals ≤19 years of age (targeted by vaccination) was significantly lower compared to the rate in adults ≥20 years of age -1% versus 4.8%. The lack of dynamics in the overall level of HBsAg carriers is likely related to the excessively low hepatitis B vaccine coverage in individuals, born before the introduction of the universal vaccination of newborns in August 1991. Anti-HCV antibodies were detected in 0.7% of the subjects.

Introduction: Nosocomial infections (NI) are frequent complications in neonatal intensive care units (NICU) which result in high morbidity and mortality. Aim: To determine and analyze the incidence, risk factors and etiologic agents of NI in newborns admitted in the NICU to help plan-ning future surveillance and prevention strategies. Materials and methods: A prospective cohort study was carried out at the NICU of St George University Hospital, Plovdiv, Bul-garia from January 1, 2017 to June 31, 2018. The number of neonates included in the study was 507. Descriptive statistics such as count,  percent, mean and standard deviation was used. Chi-square test was performed to prove associations. Odds ratios, with 95% confidence intervals, were computed from the results of the binominal logistic regression analyses. Results: Of the 507 hospitalized newborns in NICU, 48 presented with 54 NI. The incidence and the density incidence rates were 9.5% and 7.67 per 1,000 patient-days, respectively. Nosocomial infections were detected in neonates from all birth weight (BW) classes, but it was low BW and premature neonates that were at major risk to acquire them. The most common infection sites were ventilator-asso-ciated pneumonia (VAP) (67.27%), bloodstream infection (23.64%) and conjunctivitis (9.09%). Major pathogens were Gram-negative such as Klebsiella pneumoniae, E. coli, Pseudomonas aeruginosa and Acinetobacter baumannii. In the multivariate logistic regression analysis NIs were strongly associated with intubation, presence of a venous catheter, the duration of antibiotic treatment and increased CRP> 10 mg/l. Conclusions: This report highlights the burden of NIs, identifies the major focus for future NI control and prevention programs.

Introduction: Bisphosphonate-associated osteonecrosis of the jaws (BAONJ) is a side effect of treatment with bisphosphonate (BP). Reports of this complication have increased recently. Aim: To evaluate the level of knowledge of dentists from Plovdiv, Bulgaria, about possible complications of bisphosphonate therapy of patients in dental practice. Materials and methods: Three hundred and twenty-three dental practitioners from Plovdiv, Bulgaria, took part in an anonymous survey containing 25 questions, designed to evaluate the knowledge of dentists about the complications of BP therapy. Results: Oral and maxillofacial surgeons have the best knowledge about the indications and side effects of BP therapy, while dentists with a specialty in Pediatric Dentistry and General Dentistry have insufficient knowledge. Of the respondents, 17.03% are absolutely uninformed about BP and their side effects, and 1/2 declare that they have never had a patient with complications from BP therapy in their practice, probably due to a lack of awareness of the problem. Approximately half of the dentists we surveyed agree to carry out prophylactic examinations of patients receiving BP and know what the prophylactic examination includes. Only 15.48% of the respondents have correctly responded that in order to be treated as clinically healthy, patients should have stopped taking BP for more than 10 years. Conclusion: With the exception of specialists in Oral and Maxillofacial Surgery, dental practitioners in Plovdiv and the region are poorly informed about the complications associated with BP therapy. Therefore, efforts must be made to make these dentists better informed about BAONJ, especially about the methods and means of preventing this condition.

The study demonstrates the presence of immune memory and protection 5-15 years after the initial course of newborn immunization with recombinant vaccines against hepatitis B.

Hepatitis B virus infection is a global health problem. Based on the sequence divergence of the entire genome, hepatitis B virus has been classified into eight genotypes which have a characteristic geographic distribution. To date, no data are available on the molecular epidemiology of hepatitis B virus in Bulgaria. The aim of the present study was to reconstruct the epidemiological history of HBV genotypes/subgenotypes circulating in Bulgaria using a phylodynamic approach and a Bayesian statistical inference framework. Sequence analysis of the HBsAg/Reverse Transcriptase overlapping genomic regions revealed that D1 and A2 were the subgenotypes detected most frequently in the patients examined. The tMRCA estimations of the few HBV D1 Bulgarian significant clades dated back to 23-27 years ago, corresponding to the early 1980s. The HBV A2 Bulgarian sequences fell into two closely related supported clusters dated to 2003 and 1996 years, respectively, suggesting a more recent introduction of subgenotype A2 into Bulgaria. The study provides new information about the HBV subgenotypes in Bulgaria.