As New York’s hospitals filled with pneumonia patients last spring, Dr. Michael Gottlieb flashed back to the earliest days of another mysterious illness.
For months, Gottlieb had vainly treated a young man with an unrelenting fever. The man developed pneumonia from a usually harmless virus and his mouth was covered with a fungus that made it hard for him to swallow or eat.
Another young man soon turned up with similar symptoms. Then, over the course of a few months, three more previously healthy Los Angeles men came down with the same constellation of problems.

Dr. Michael Gottlieb displays a model of an HIV-infected cell during an interview Friday, June 1, 2001, at the Synergy Hematology-Oncology Medical Associates, Inc. office…
Dr. Michael Gottlieb displays a model of an HIV-infected cell during an interview Friday, June 1, 2001, at the Synergy Hematology-Oncology Medical Associates, Inc. office in Los Angeles. Gottlieb published a brief note in a weekly report put out by the Centers for Disease Control on June 5, 1981, noting the odd cases of five homosexual men who had contracted a form of pneumonia normally found only in those with severely weakened immune systems. The report, largely ignored, was the first official notice of what is now recognized as AIDS.
As he watched them die, Gottlieb was both concerned and intrigued. At 33, he was roughly the same age. Their care became personal as well as…