New United Nations data shows that global HIV/AIDS infection rates and deaths are down and treatment is up, but new infections remain a serious challenge in certain high-risk groups.In a report launched Tuesday ahead of World AIDS Day on Dec. 1, UNAIDS reports that of the nearly 38 million people globally living with HIV — the virus that causes AIDS — more than 24 million patients are receiving antiretroviral therapy (ARVs). That is a significant increase from nine years ago, when about 7 million people were accessing the life-saving treatment.UNAIDS says about 8 million people do not know they are infected with HIV.AIDS-related deaths worldwide are also down by more than half since 2004. Some 770,000 people died of the disease last year.”The gains continue to be made against the epidemic, but those gains are getting smaller year after year,” said Ninan Varughese, director of the UNAIDS New York office.He …