HCV transmission in high-risk communities in Bulgaria

Abstract

Background The rate of HIV infection in Bulgaria is low. However, the rate of HCV-HIV-coinfection and HCV infection is high, especially among high-risk communities. The molecular epidemiology of those infections has not been studied before. Methods Consensus Sanger sequences of HVR1 and NS5B from 125 cases of HIV/HCV coinfections, collected during 2010–2014 in 15 different Bulgarian cities, were used for preliminary phylogenetic evaluation. Next-generation sequencing (NGS) data of the hypervariable region 1 (HVR1) analyzed via the Global Hepatitis Outbreak and Surveillance Technology (GHOST) were used to evaluate genetic heterogeneity and possible transmission linkages. Links between pairs that were below and above the established genetic distance threshold, indicative of transmission, were further examined by generating k-step networks. Results Preliminary genetic analyses showed predominance of HCV genotype 1a (54%), followed by 1b (20.8%), 2a (1.4%), 3a (22.3%) and 4a (1.4%), indicating ongoing transmission of many HCV strains of different genotypes. NGS of HVR1 from 72 cases showed significant genetic heterogeneity of intra-host HCV populations, with 5 cases being infected with 2 different genotypes or subtypes and 6 cases being infected with 2 strains of same subtype. GHOST revealed 8 transmission clusters involving 30 cases (41.7%), indicating a high rate of transmission. Four transmission clusters were found in Sofia, three in Plovdiv, and one in Peshtera. The main risk factor for the clusters was injection drug use. Close genetic proximity among HCV strains from the 3 Sofia clusters, and between HCV strains from Peshtera and one of the two Plovdiv clusters confirms a long and extensive transmission history of these strains in Bulgaria. Conclusions Identification of several HCV genotypes and many HCV strains suggests a frequent introduction of HCV to the studied high-risk communities. GHOST detected a broad transmission network, which sustains circulation of several HCV strains since their early introduction in the 3 cities. This is the first report on the molecular epidemiology of HIV/HCV coinfections in Bulgaria.

Molecular Epidemiological Analysis of the Transmission Clusters of the Hiv-1 Circulating Recombinant Forms Crf01_ae and Crf02_ Ag in Bulgaria

“…HIV-1 CRF01_AE and CRF02_AG have been found to be the most prevalent among the most vulnerable groups, such as PWID. In addition, according to our epidemiological data, vulnerable individuals represent a significant proportion of the current HIV+ population in Bulgaria and since 2005 there has been a sharp increase in the incidence of HIV among PWIDs, leading to an outbreak with significant involvement of the CRF01_AE and CRF02_AG viruses (4,10,11). The purpose of this national representative study was to analyse the underlying HIV-1 transmission clusters of the two most widespread recombinant forms of HIV-1 CRF01_AE and CRF02_AG in Bulgaria using the most up-to-date methods for phylogenetic analysis.…”

Hepatitis C virus genotype analysis in patients with chronic hepatitis in North Eastern Bulgaria

“…A study by Ganova-Raeva et al 27 . noted HCV transmission of subtype 1a to be most prevalent (54%), followed by 1b (20.8%), 2a (1.4%), 3a (22.3%), and 4a (1.4%), in high risk drug addicted population groups of HIV/HCV coinfections in Western Bulgaria, Sofia, Plovdiv, and Peshtera 27 . However, this study includes patients from another region, whereas our study describes North Eastern Bulgaria.…”

Prevalence of hepatitis C in the adult population of Bulgaria: a pilot study

“…The highest rates of chronic HCV prevalence in Europe are found among PWID ranging from 13.8 to 84.3% (anti-HCV) [ 31 ]. Studies in Bulgaria have found high levels of HCV transmission among PWID and other groups [ 32 ], with one study in Sofia reporting 73.9% of 773 PWID being anti-HCV positive [ 33 ]. GP surveys are not ideal to collect representative data on PWID.…”