8. What is the geographic distribution of chronic infection?

If you’re in a high area, your lifetime risk of getting infected is higher than sixty percent. And for most of those areas, it’s up to eighty or ninety percent. If you’re in an intermediate area, then your lifetime risk of infection is somewhere between twenty and sixty percent. And if you’re in a low risk area, your risk is less than twenty percent. So in the high risk area people get infected as young children. In the intermediate area, you have some people getting infected as young children and some getting infected at older ages. And in the low risk area, almost all of the infections are adults and usually because of one risk behavior or another. So, these are the areas of the world where you find the high, intermediate, and low risks and you can see that the red areas cover large parts of East Asia, Southeast Asia, Sub-Saharan Africa. The band in South America are South American Indians. It’s not the European populations that are infected and so it’s actually the Amazon Basin where the Indian populations have twenty percent or higher prevalence of hepatitis B. And the same is true for Northern Canada, Alaska, and Greenland; those are by and large either Indian or Inuit populations. And the intermediate populations in yellow, a lot of Eastern Europe and the Soviet Union still have pretty high prevalence of chronic carriers.