According to UNAIDS（联合国艾滋病规划署）estimates there were 38.6 million adults and 3.2 million children living with HIV at the end of 2002, and during the year 5 million new people became infected with the virus. Around half of all people who become infected with HIV do so before they are 25 and are killed by AIDS before they are 35. 95% of the total numbers of people with HIV live in the developing world. But HIV still remains a threat to people of all ages and nationalities.