A lot has changed since the first cases of AIDS were reported in 1981. Globally, AIDS-related deaths have dropped by more than 55% since 2004, the deadliest year on record. But, the road to effective treatment for HIV, the virus that causes AIDS, was long. Maggie Hoffman-Terry, a physician and researcher who's been on the front lines of the epidemic for decades, explains how treatment has evolved, its early drawbacks, and the issue of access to medications. Follow Maddie on Twitter — she's @maddie_sofia. And email the show at shortwave@npr.org.