**1. Introduction**

Hepatitis B Virus (HBV) is chronically carried by around 400 million people worldwide and about one million die annually as result of developing liver cirrhosis and hepatocellular carcinoma [1–3]. The infection is mainly present in Middle East, South-East Asia, sub-Saharan Africa, Central and South-America, and Eastern-Europe with prevalence >8% of population [4]. A migratory flow that had occurred in last twenty years from these countries to the industrialized countries resulted in an increase in HBV prevalence the industrialized countries [1,5]. Between 5 and 10% of infected individuals become chronic carriers in their adulthood, while 85 to 95% in their infancy [6].

Hepatitis B virus is transmitted through blood and body fluids, hence certain types of behaviors increase the risk of infection, such as sharing personal items (toothbrushes, razors, etc.), use of contaminant needles for intravenous drugs or ear pricing and tattooing, and practicing unsafe sex. Hemodialysis and hemophiliacs patients as well as Healthcare and emergency service workers are also at higher risk [7].

HBV genome has a high rate of mutation when compared to other DNA viruses due to the high spontaneous error rate of the viral reverse transcriptase and lack of proofreading mechanism. It is estimated approximately 1.4–3.2 × 10−<sup>5</sup> per genome. Accordingly, HBV can be classified into eight genotypes A-H that accounts for 8% or more in the complete nucleotide sequence on inter-sequence divergence [8,9]. Studies on HBV genotypes show a distinct geographical distribution around the world [10]. In general, genotype A is pandemic, but most prevalent in North West Europe, North America, Central Africa [11], and India [8,12]. Genotypes B and C are prevalent in Asia [1,13], especially in the populations of Eastern Asia and the Far East [3]. Genotype D is distributed worldwide with the highest prevalence in the Mediterranean region [3,9,14]. Genotype E and F are predominant in West Africa and in the Amerindian population, respectively [1,9,13]. Recently, genotype G was identified in the USA and France [1]. Genotype H was also recently found in Central America [15]. A remarkable di fference in the clinical and virologic characteristics between the patients with di fferent genotypes has been reported [2].

HBV genotypes are reported to be responsible for the di fferences in the natural history of chronic infection and they play a significant role in clinical manifestation of infection and response to antiviral therapy [16]. Therapeutically, patients that are infected with genotypes A, B, D, and F show frequent spontaneous HBeAg seroconversion when compared to genotype C. Whereas, patients that were infected with genotype E have higher frequency of HBeAg positivity and higher viral loads as compared to patients that were infected with genotype D [17].

Epidemiological data regarding HBV in any country would provide significant information to program managers and health planers to control and manage the infection with reference to its etiological spectrum. In the present study, we aim to determine the prevalence of the various HBV genotypes in the Kingdom of Bahrain. This study also aims to determine various sociodemographic factors and hepatic biomarker associated with the prevalence and the possible risk factors for HBV transmission in Bahrain.
