The 18th International AIDS Conference has opened in Vienna to UN pleas and activists' clamour for countries not to backtrack in the 29-year war on acquired immune deficiency syndrome. The six-day forum is expected to draw more than 20,000 scientists, policymakers and grassroots workers to seminars and workshops on scores of issues related to AIDS and the human immunodeficiency virus, the HIV. In a video message, UN Secretary General Ban Ki-moon said that after arduous effort, significant progress was being made against AIDS. But this could be threatened if countries failed to pursue their commitments. He said some governments are cutting back on their response to AIDS. This should be a cause for great concern to us all. AIDS funding by the G8 countries and other rich economies fell back slightly last year, to 7.6 billion dollars after 7.7 billion dollars in 2008, as a result of the economic recession. Julio Montaner, president of the International AIDS Society which is organising the conference, lashed any leaders who argued funds for AIDS had to be slimmed at a time of belt-tightening. According to UN figures, AIDS has claimed more than 25 million lives since the disease first came to light in 1981 and more than 33 million people have HIV.