The head of the United Nations agency for combating AIDS Peter Piot has said HIV infection is the biggest epidemic in modern history. He was speaking on the day the UN agency released a report saying an estimated 38 million people had the virus but more than half of them didn't know it. "I think the response to AIDS over the last 25 years has been characterized as what I like to call it, a haphazard crisis management and will campaign and then, after 1 year or 2 years, the money is running out. And we just can't deal with the epidemic in this way. This is not something that can be dealt with on fiscal year but fiscal year basis. We need an engagement, a commitment for over 10 years, over a generation, and sustain it."