[Hepatitis B genotype distribution in Portugal and worldwide]

Infection with Hepatitis B is a public health problem worldwide. In Portugal, around 1% of the population is chronically infected. Some genotypes are only predominant in some geographical regions; however migration around the world can lead to the dissemination of the different genotypes. The heterogeneity of hepatitis B genotypes seems to be related to differences in clinical evolution of the infection and response to antiviral treatment.

The present study was designed to review the worldwide geographical distribution of Hepatitis B genotypes, and to analyze the possible relationships with the distribution of genotypes in Portugal.

Studies of interest were identified by search on indexed journals. Search of Portuguese information was extended to conference proceedings in the areas of Virology and Hepatology.

In Asia genotypes B and C were prevalent; in the North of Africa the genotype D was prevalent, and in the East Coast genotype E was predominant. In the American continent the most predominant genotypes were A, D, F, G and H. In South America, Venezuela and Argentina showed a high prevalence of genotype F, in Brazil genotype A was prevalent. In Europe, including Portugal, genotypes A and D were predominant. In Portugal genotypes C, E and F were observed in Portuguese patients and in immigrant patients.

The pattern of global migration affects the pattern of genotype distribution, introducing genotypes in regions where the clinical outcome can differ from the population of origin. The genotypic distribution found in Portugal seems to be associated not just with being a European country, but also with immigration from Africa, Brazil, Eastern Europe, and Asian countries like China. The study of the hepatitis B genotypic distribution should be extended to all regions in Portugal, namely Lisbon where the immigration levels are higher, as well as to the autonomous regions of Portugal, the Azores and Madeira islands. The relationship between hepatitis B genotypes and pathogenicity remains largely unknown, however evidence suggests the clinical and public health relevance of these genotypes. Further research is needed, not only to know how genotypes affect the severity of liver disease, but also to understand if and how the response to treatments is influenced by hepatitis B virus genotype.