| B | 2 billion have been infected at some time in their life. Currently 350 million chronic carriers | Africa, Asia, and South America 5–10%. China and Taiwan 10–20% | Mother to infant (vertical) Child to child Sexual |
| C | 170 million carriers — 3% of the world’s population. | 2–5% of the population in most resource poor countries. 10% in northern China and parts of Africa | Parenteral: reusable medical equipment, tattooing, traditional scarification and circumcision practices, blood products, injecting drug use |
| D | 10 million carriers | Mediterranean basin, Middle East, central Asia, west Africa, Amazon basin, and some Pacific Islands. New areas identified in China, Japan, northern India, and Albania | Parenteral, injecting drug users. Horizontal, non-sexual, intrafamilial spread (exact mechanism is unknown) |