in sub-Saharan Africa, including its status and modes of transmission. The chapter ends with a discussion of remaining gaps in knowledge and a set of recommendations for future research.
The origin of HIV continues to be an enigma, and the timing of the first human infection remains unknown. Attempts to determine the origins of the disease led to early speculation that AIDS originated in Africa. Not surprisingly, this speculation led many African leaders to resent the implication that Africans were to blame for AIDS. The controversy about the origin of AIDS resulted in a "backlash" and denial that HIV even existed within high-risk populations in sub-Saharan African countries and proved very unhelpful for designing effective prevention programs. Efforts to acknowledge that the problem existed and to initiate efforts to control its spread were delayed in some countries for several years. Because theories about where and when AIDS originated have become so entangled in politics, and because the epidemic is now too far advanced for the question to really matter, attempts to find definitive answers to these questions have been given a low priority. There are a few isolated reports in the literature in the 1970s and even earlier of people dying of opportunistic infections that have now become known as the trademarks of AIDS (Henig, 1993). However, AIDS was not recognized as a clinical entity until 1981. In Africa the first reports of AIDS-like syndromes and "slim" appeared in the literature between 1983 and 1985 (Van de Perre et al., 1984; Piot et al., 1984; Serwadda et al., 1985). Since the early 1980s, the prevalence of HIV infection among certain populations in Africa has increased dramatically, and it is expected to grow even more rapidly in the future. Factors in the spread of HIV are discussed in Chapters 2 and 4 with regard to the larger societal context and individual attitudes and behavior, respectively.
As of December 1994, nearly 350,000 AIDS cases had been reported from the African region (World Health Organization, 1995a). As noted earlier, this sum represents one-third of the global number (1,025,073) of AIDS cases reported since the start of the epidemic. Allowing for under-diagnosis, incomplete reporting, and reporting delays, WHO estimates that more than 3 million cases of AIDS have occurred in Africa, comprising 70 percent of the global total of 4.5 million. In sub-Saharan Africa, 11 million adults are estimated to have been infected with HIV. This number represents nearly two-thirds of the estimated 18 million cumulative HIV infections that have occurred worldwide. More than half of these 11 million infected adults are women, and as many as 1 million African