A survey of existing knowledge about the etiology, treatment, prevention, and epidemiology of HIV infection and AIDS is presented, with particular emphasis on Africa and the Third World. A brief introduction argues that the impact of AIDS in Africa is likely to be especially severe because of poverty and lack of development. The 1st chapter discusses the HIV virus and its mode of attack on the body's immune system, describes related retroviruses, explains and diagrams how the ELISA, Western Blot, and other diagnostic tests work, and describes the common signs and symptoms of the various stages of HIV infection. The 2nd chapter assesses the prospects for development of a vaccine, the difficulty of determining the lethality of HIV infection after only a few years of experience, and the efficacy of AZT, alpha interferon, and other possible treatments. Existing epidemiologic data, the divergent transmission pattern in different world regions and their recent trends, high risk behavior, the probable future course of the epidemic, and possible social and economic effects of the epidemic are discussed in chapter 3. The following chapter discusses AIDS prevention campaigns, safer sex, condom use, and IEC campaigns for the public, with examples from Kenya, Uganda, Rwanda, the US, and elsewhere. Chapter 5 focuses on the epidemic in Africa. Topics covered include the possible African origin of HIV, the deficiencies of existing epidemiologic data, AIDS control programs in Africa, and special problems in Africa related to the possibility of infection during lactation and the possible dangers of vaccinating children seropositive for HIV. The next chapter sketches a general strategy for AIDS prevention and outlines the role of WHO. The final chapter assesses knowledge of the level of infection in Latin America, the Middle East, Asia and the Pacific, North America, and Western and Eastern Europe.