Abstract
Hepatitis B virus has been coexisting with human beings for longer than 85 million years over several million generations on our planet. The virus has been transmitted from hepatitis Be antigen positive mothers to newborn babies or from community members to infants through close contact at the immunologically immatured stage to HBs antigen.
The number of hepatitis B virus carriers is estimated to be 215 millions in the world, corresponding to more than 5% of general population on our planet. Of these, 78% of hepatitis B virus carriers in the world are now living in Asian countries.
There are four main subtypes of the virus, “ayw”, “adr”, “adw”and “ayr”which are coded by the virus genome. Therefore, to elucidate the route of transmission of this virus, distribution of these subtypes has been investigated through WHO collaborative studies.
Since the virus was mainly transmitted through maternal or intrafamiliar route from generation to the next generation, analysis of the subtype distribution and interaction of different subtype groups will give information about the origin or movement of various ethnic groups in Asia. There are three zones with predominant characteristic subtype in Asia as described as follows.
Zone“ayw”is mainly west Asia (USSR, Xinjiang, Meinggu, Xizang, north India, Iran, Israel) extending to Mediterranean area and north and central Africa, distributed over steppe or desert areas.
Zone“adr”is distributed from north east Asia (Japan main islands, Korea, Han ethnic group in mainland China, originally in north) to south part of Asian continent such as Laos, Thailand and Malaysia, spreading over agrarian groups in green woods area. Tamil-nadu and Nepal are the borderline between“adr”and“ayw”zones.
Zone“adw”is the most southern parts of Asia, such as Okinawa, Amami, Taiwan, Philippines, Indonesia, minorities in southern China, southwest coast of India and east coast of Africa continent, crossing over Indian Ocean and Pacific Ocean to American natives.
