Geographic distribution of Hepatitis B Virus genotypes

Regarded as pandemic, Hepatitis B Virus genotype A is predominantly found in North America, Northern and Western Europe as well as Central Africa. Genotype B is most common in Asia including Japan, Taiwan, Indonesia, China and Vietnam. Genotype C is predominant in East Asia and countries of the Pacific rim while genotype D, another pandemic genotype, is most common in the Mediterranean, India, the Middle East and North America. Hepatitis B Virus genotype E is mainly detected in sub-Saharan Africa, genotype F in South and Central America as well as Alaska, and genotype G in Central and North America as well as Europe. The most recent Hepatitis B Virus genotype identified, genotype H, has been found in the United States, Mexico and Central America[1].Recently, however, a novel genotype I has been discovered.

However, although these general geographical distributions provide insight into the regional predominance of Hepatitis B Virus genotypes, the effect of travel and immigration must be kept in mind. For example, in an ongoing study involving 17 liver centres across the United States, scientists found at least seven Hepatitis B Virus genotypes in the patient population with genotypes C and A being most common followed by B and D.

It is unknown whether the global distribution of Hepatitis B Virus genotypes is related to racial or ethnic differences, modes of transmission, environmental aspects or all of these factors. Further studies are required to determine the correlation of Hepatitis B Virus genotype distribution with mode of transmission or host factors including ethnicity.

Guettouche and Hnatyszyn: Chronic hepatitis B and viral genotype: the clinical significance of determining HBV genotypes in Antiviral Therapy - 2005