AIDS in Africa: a retrospective.

In 1983, two years after the initial recognition of AIDS in the USA (1,2), a series of investigations was initiated in central Africa to determine the extent of the clinical problem of AIDS and to examine its transmission patterns within the African region. These first investigations of AIDS in Africa were prompted by the finding of clinical AIDS cases among Africans residing in Europe, which differed from cases among Europeans by having a nearly equal male-to-female ratio and 90% had no identifiable risk factors (3-6). Two sentinel reports published one year later documented the presence of AIDS in selected urban centres of equatorial Africa (7,8). Clinically, these cases were recognized by life-threatening enteropathic illnesses referred to as "slim disease," oesophageal candidiasis, Kaposi's sarcoma, and cryptococcal meningitis (9-11). Most of these studies on clinical cases suggested that while the disease may have been endemic in Africa, it did not become truly epidemic until the late 1970s and early 1980s, a pattern similar to that in the United States and Haiti. The most unusual characteristics of AIDS among Africans were the equal distribution of cases between men and women and the high frequency of cases among commercial sex workers and their clients. In contrast to the industrialized world where the epidemic was entrenched among homosexual men and injecting drug users, there was little or no evidence for this pattern in Africa. This raised a series of debates regarding the modes of transmission in Africa, which ultimately was resolved following the introduction of serological tests for HIV-1, allowing for more detailed epidemiological studies on transmission, and investigations into the natural history and clinical presentation of HIV infections (12-16). Two years of detailed studies in Kinshasa, Zaire (now the Democratic Republic of the Congo) were presented in our paper entitled "AIDS in Africa: an epidemiologic paradigm" (17), which is reproduced in the following pages. From these early investigations in Kinshasa, it was evident by 1986 that HIV/ AIDS was an escalating epidemic in central Africa with an estimated annual incidence of AIDS of 550-1000 cases per million adults, with 1-18% of healthy blood donors and pregnant women infected with HIV, and 27-88% of female commercial sex workers serologically positive for HIV. Our early estimate of HIV incidence in central and east Africa was 0.75% among the general population. In addition, we found that the male-to-female ratio of cases was 1:1 with age and sex-specific rates slightly greater in females Although we knew the problem was severe in 1986, none of us would have predicted the magnitude the epidemic would reach today. In 1986 we projected that the annual number of AIDS cases would be 400 000, whereas in 2000 there were three million (18). We estimated that 1-2 million Africans were HIV-infected in 1986, whereas today 25.3 million Africans are infected and the adult prevalence for the continent is now 8.8% (18). We estimated in 1986 that the annual incidence of infection was 0.75% among the general population, and today incidence rates range from 1.5% to 3% in rural populations, and from 5% to 15% among higher risk populations (19). Overall, 3.8 million Africans became newly infected last year alone. Since the beginning of the epidemic, 5. …