Epidemiology of hepatitis C in Croatia in the European context.

We analyzed prevalence, risk factors and hepatitis C virus (HCV) genotype distribution in different population groups in Croatia in the context of HCV epidemiology in Europe, with the aim to gather all existing information on HCV infection in Croatia which will be used to advise upon preventive measures. It is estimated that 35000-45000 of the Croatian population is chronically infected with HCV. Like in other European countries, there have been changes in the HCV epidemiology in Croatia over the past few decades. In some risk groups (polytransfused and hemodialysis patients), a significant decrease in the HCV prevalence was observed after the introduction of routine HCV screening of blood/blood products in 1992. Injecting drug users (IDUs) still represent a group with the highest risk for HCV infection with prevalence ranging from 29% to 65%. Compared to the prevalence in the Croatian general population (0.9%), higher prevalence rates were found in prison populations (8.3%-44%), human immunodeficiency virus-infected patients (15%), persons with high-risk sexual behavior (4.6%) and alcohol abusers (2.4%). Low/very low prevalence was reported in children and adolescents (0.3%) as well as in blood donors (0%-0.009%). In addition, distribution of HCV genotypes has changed due to different routes of transmission. In the general population, genotypes 1 and 3 are most widely distributed (60.4%-79.8% and 12.9%-47.9%, respectively). The similar genotype distribution is found in groups with high-risk sexual behavior. Genotype 3 is predominant in Croatian IDUs (60.5%-83.9%) while in the prison population genotypes 3 and 1 are equally distributed (52.4% and 47.6%). Data on HCV prevalence and risk factors for transmission are useful for implementation of preventive measures and HCV screening.

Current status of human papillomavirus vaccination implementation in central and eastern Europe.

We present a review of the current implementation status of vaccination against human papillomaviruses (HPV) and available data concerning the burden of HPV infection and HPV type-specific distribution in 16 central and eastern European countries: Albania, Bosnia and Herzegovina, Bulgaria, Croatia, the Czech Republic, Estonia, Montenegro, Poland, Romania, Serbia, Slovakia, Slovenia, and The Former Yugoslav Republic of Macedonia. At least one current HPV prophylactic vaccine is registered in all central and eastern European countries except Montenegro. Six counties-Bulgaria, the Czech Republic, Latvia, Romania, Slovenia, and Former Yugoslav Republic of Macedonia-have integrated the HPV vaccination into their national immunization program and currently provide routine vaccination free of charge to the primary target population. Ten countries have not integrated HPV vaccination into the national immunization program. The key reasons for lack of implementation of HPV vaccination into the national immunization program are the high vaccine cost and negative public perception. Vaccination of males is not recommended in any country in the region.

[Epidemiology of viral hepatitis]. / Epidemiologija virusnih hepatitisa.

Understanding the country-specific epidemiology of disease, which may vary greatly among countries, is crucial for identifying the most appropriate preventive and control measures. An overview of the local epidemiology of viral hepatitis in Croatia is given in this paper. The overall prevalence of hepatitis B in Croatia is low (less than 2% HBsAg carriers in the general population). Hepatitis B incidence and prevalence began to decline significantly following the introduction of universal hepatitis B vaccination in 1999. Information on HBsAg seroprevalence is derived from routine testing of certain subpopulations (pregnant women, blood donors) and seroprevalence studies mostly targeted at high-risk populations. Universal childhood vaccination against hepatitis B remains the main preventive measure. We recommend testing for immunity one to two months after the third dose of hepatitis B vaccine for health-care workers. The incidence and prevalence of hepatitis C have also been declining in the general population. The main preventive measures are ensuring safety of blood products, prevention of drug abuse, and harm reduction programs for intravenous drug users. Hepatitis A incidence has declined dramatically since fifty years ago, when thousands of cases were reported annually. In the last five years, an average of twenty cases have been reported per year. The reduction of hepatitis A is a consequence of improved personal and community hygiene and sanitation. Hepatitis D has not been reported in Croatia. The risk of hepatitis D will get to be even smaller as the proportion of population vaccinated against hepatitis B builds up. Hepatitis E is reported only sporadically in Croatia, mostly in persons occupationally in contact with pigs and in travelers to endemic countries. In conclusion, Croatia is a low prevalence country for hepatitides A, B and C. Hepatitis D has not been reported to occur in Croatia and there are only sporadic cases of hepatitis E. Since hepatitis A is a rare disease occurring sporadically, which is a consequence of improved sanitation and hygiene, hepatitides B and C are the main causes of viral hepatitis in Croatia. The introduction of universal mandatory hepatitis B vaccination of schoolchildren in 1999 resulted in a decrease in the incidence of hepatitis B, which is most pronounced in adolescents and young adults, and further decrease in the incidence and prevalence is expected as the pool of susceptible individuals decreases through vaccination. The incidence of hepatitis C is decreasing as well. In spite of a relatively favorable epidemiological situation, hepatitis B and C are still a significant public health burden with an estimated 25,000 persons chronically infected with HBV and about 40,000 persons chronically infected with HCV in Croatia.

Vaccine regulations in Croatia.

In this paper legal prerequisites for vaccine licensure in Croatia are discussed. The Croatian legislation concerning vaccine licensing, marketing authorisation and utilization is reviewed. The procedures for including a vaccine into the Mandatory Childhood Vaccination Programme are also discussed with focus on Human papillomavirus (HPV) vaccines. Non-obligatory vaccination recommendations are given when according to professional opinion; vaccination is beneficial for the vaccinee. There is little doubt that HPV vaccines should be recommended for preadolescent girls in Croatia. However, reaching a decision on its possible introduction into the Childhood Vaccination Programme will require careful consideration of the larger picture and a comparison of the cost-effectiveness of a mandatory vaccination against other competing public health priorities.

Subacute sclerosing panencephalitis in Croatia (1994-2004).

We studied five patients with SSPE during a 10-year period (1994-2004). The first clinical symptoms developed at the age of 5-11 years. All patients were vaccinated regularly against measles according to the official immunization schedule. One patient had measles at the age of 18 months. Two of them had a history of morbilliform rash (unrecognized measles) at the age of six and seven months, respectively. In two patients, with no history of measles before vaccination the disease started after varicella infection. Using complement-fixation (F) test and EIA, antibodies to measles virus (MV) were detected in the CSF and sera of all patients. The CF-antibody titers ranged from 1:1024 to 1:65536 in sera and from 1:16 to 1:128 in CSF samples. MV antigen was detected in brain imprints using IFA in two patients. Electron microscopic analysis revealed intranuclear viral inclusions (MV nucleocapsids). Using RT-PCR, viral RNA was found in both patients. Nucleotide sequence analysis showed that the viruses found in the brain tissue belonged to the wild-type MV D6 genotype [7].

[MHC tetramers: tracking specific immunity]. / MHC-tetrameri: na tragu specificnoj imunosti.

In an adaptive immune response, antigen is recognized by two distinct sets of highly variable receptor molecules: (1) immunoglobulins, that serve as antigen receptors on B cells and (2) the antigen-specific receptors on T cells. T cells play important role in the control of infection and in the development of protective immunity. These cells can also mediate anti-tumor effects and, in case of autoimmune syndromes, contribute to the development and pathology of disease. The specificity of T cells is determined by T cell receptors (TCR). Understanding of the success of immune responses requires the direct measurement of antigen-specific T lymphocytes. Cell with major histocompatibility complex (MHC) class I molecules are able to present antigens to antigen-specific CD8+ cytotoxic T lymphocytes. MHC class I molecules present small peptides (epitopes) processed from intracellular antigens such as viruses and intracellular bacteria. MHC class I molecules in humans are designated as human leukocyte antigen (HLA) class I and divided into HLA-A, -B and -C. CD8+ T cells recognize MHC class I molecules and after activation produce proteins that destroy infected cells. MHC class II molecules receive their peptides mainly from extracellular and soluble antigens and present them to the CD4+ T helper cells. A recently described technique that can be used in flow cytometry enables us to quantify ex vivo antigen-specific T cells by binding of soluble tetramer MHC-peptide complexes attached to fluorochrome. Quantitative analyses of antigen-specific T cell populations provide important information on the natural course of immune responses. The interaction of T cell receptors on T lymphocytes with tetrameric MHC-peptide complexes mimics the situation on the cell surface, and allows for reliable binding. Tetramers consist of four biotinylated HLA-peptide epitope complexes bound to streptavidin conjugated with fluorescent dye. Tetramer technology has sensitivity of detection as little as 0.02% of total cytotoxic T cell pool or T helper cell pool (i.e. approximately 1 in 50.000 lymphocytes). The combination of this technology with intracellular cytokine staining methods opens up significantly better ways of studying these cells than previously possible, allowing immunologists to look at their life cycle (activation and proliferation), manner of death (aging and apoptosis) and effector function (cytotoxic potential and cytokine production). MHC tetramers class I have yielded useful insights into in vivo dynamic and function of antigen-specific CD8+ T cells in viral infections, parasitic infections, cancer, autoimmune disease and transplantation. This knowledge is of special interest for immunotherapy, diagnostic monitoring of T cell mediated immunity, and the development of new vaccination strategies. There is some possibility for cell therapy with antigen-specific CD8+ T cells for various diseases including cancer and viral infections. Targeted immunotherapy of selective deletion of auto--or alloreactive T cells with MHC tetramers may be important for the treatment of autoimmune disease, or to prevent the rejection of transplanted organs. The utility of this technique for the immunotherapy in vivo needs to be confirmed and modified in further research. Understanding how antigen-specific cells develop and function in different circumstances and pathologies will be the key to unravelling the secrets of cellular immune system.