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Epidemiology, Virology and Pathogenesis of Viral Hepatitis with a Focus on Latin America

Worldwide, ≥350 million people are chronically infected with HBV and 170 million with HCV. Approximately 1 million people die directly each year from the consequences of viral hepatitis, including cirrhosis and liver cancer. Nearly two-thirds of cases of liver cirrhosis and three-quarters of cases of liver cancer are due to chronic infection with either HBV or HCV [1] and liver cancer has now emerged as the third most common cancer in the world [2]. This disease burden is carried disproportionately across the various regions of the world, with higher prevalence areas such as Asia–Pacific, Africa, Eastern Europe and Latin America shouldering the heaviest load. The World Health Organization (WHO) has recently released its Global Hepatitis Strategy [3] focusing on four key areas: partnerships, mobilization and communication; data for policy and action; prevention of transmission; and screening, care and treatment. This Global Hepatitis Strategy will be translated at the regional level in order to make a significant impact on viral hepatitis. In keeping with this approach, the 2nd International Theoretical Course on Viral Hepatitis and the Human Host was held in São Paulo, Brazil, 12–15 March 2012, which focused on five themes: epidemiology and evolution of HBV, HCV and HDV; phylogenetic approaches to the study the hepatitis viruses and the human population infected by them; advances in antiviral treatment of infection by HBV and HCV in patients monoinfected and coinfected with HIV; application of new methods for sequencing and its application to the study of hepatitis virus biology; and immunogenetics and the hepatitis viruses. During this meeting, a special workshop on ‘hepatitis B genotype F’ was included, and was supported by an unrestricted educational grant from Gilead Sciences, USA, because this topic was identified by the meeting organizers as an important ‘unmet area and need’ in viral hepatitis. Genotype F is common on the American continent, particularly in Native American populations and in the Spanish speaking countries, from Argentina to Central America; in Mexico and Guatemala this genotype is replaced by genotype H as the most common genotype. Thus, HBV genotypes F and H are primarily found in indigenous populations in Latin America, and surprisingly little is known about the response of these genotypes to therapy. From the course and workshop, this Spotlight Issue has emerged and is divided into four sections: epidemiology of viral hepatitis including hepatocellular carcinoma in Latin America; HBV genotypes F and H – clinical, therapeutic and virological issues; origins and evolution of HBV – theoretical, population-based and phylogenetic approaches; and recent advances in viral hepatitis. HBV is classified in the family Hepadnaviridae with ten genotypes (A–J), and numerous subgenotypes, whereas HCV is classified within the family Flaviviridae, genus Hepacivirus, and is divided into seven genotypes (1–7) also with a number of subtypes. Epidemiological data suggest that 7–12 million people in Latin America are chronically infected with the HBV and, furthermore, HDV coinfection/superinfection is a significant public health issue. The overall prevalence of anti-HCV antibody in Latin America is approximately 1.5%. Thus, the WHO Global Hepatitis Strategy represents an important opportunity for countries of Latin America to move forward with their control programmes within the framework.