The earliest convincing evidence of the human immunodeficiency virus (HIV) that causes the acquired immune deficiency syndrome (Aids) was gathered in 1959 amidst the collapse of European colonial rule in Africa. In January 1959 rioters briefly seized control of the African townships of Leopold ville, the capital of the Belgian Congo, shocking its rulers into frantic decolonisation. In the same year an American researcher studying malaria took blood specimens from patients in the city. When testing procedures for HIV became available during the mid 1980s, 672 of his frozen specimens from different parts of equatorial Africa were tested. Only one proved positive. It came from an unnamed African man in Leopoldville, now renamed Kinshasa. The test was confirmed by the Western Blot technique - generally considered the most reliable method - and by different procedures in three other laboratories. Although nothing of this kind can be absolutely certain, there are strong grounds to believe that HIV existed at Kinshasa in 1959 and that it was rare.

One importance of the Kinshasa case is to establish a date by which HIV existed, but in itself the case does not imply that the Aids epidemic began in western equatorial Africa. If that unnamed African had been the first person ever infected with HIV, it would have been an incredible coincidence. Once Aids was recognised as a medical condition early in the 1980s, researchers found several early accounts of patients whose recorded symptoms had resembled it. Luc Montagnier, whose laboratory first identified HIV, thought that the earliest case had been an American man who died in 1952 after suffering fever, malaise, and especially the Pneumocystis carinii pneumonia that afflicted later American Aids patients, but no blood had been stored for later testing and the symptoms demonstrated only suppression of the immune system, for which there could have been reasons other than HIV. The same was true of a Japanese Canadian who died in 1958 and a Haitian American in 1959. More convincing was the case of a fifteen-year-old, sexually active American youth who died in 1969 with multiple symptoms including an aggressive form of Kaposi's sarcoma, a tumour common in later Aids patients.