#3. U.N. Dials Back AIDS Estimates

The United Nations revealed it had overestimated the number of people infected with HIV by some 6.3 million worldwide and lowered the 2007 total to 33.2 million. The reduction is based on better reporting methods, particularly in India and sub-Saharan Africa. Efforts to curb the disease also appear to be working, with the new report noting that annual infection rates likely peaked in the late 1990s. But public-health advocates worry these signs of improvement could lead to complacency. Dr. Andrew Zolopa, an HIV expert at Stanford, warns against "lowering our guard," adding that 33.2 million is "still a very big number."