Projections of HIV infections and AIDS cases to the year 2000.

After the recognition of AIDS (acquired immunodeficiency syndrome) in the early 1980s, uncertainty about the present and future dimensions of HIV (human immunodeficiency virus) infection led to the development of many models to estimate current and future numbers of HIV infections and AIDS cases. The Global Programme on AIDS (GPA) of the World Health Organization (WHO) has developed an AIDS projection model which relies on available HIV seroprevalence data and on the annual rate of progression from HIV infection to AIDS for use in areas where reporting of AIDS cases is incomplete, and where scant data are available to quantify biological and human behavioural variables. Virtually all models, including the WHO model, have projected large increases in the number of AIDS cases by the early 1990s. Such short-term projections are considered relatively reliable since most of the new AIDS cases will develop in persons already infected with HIV. Longer-term prediction (10 years or longer) is less reliable because HIV prevalence and future trends are determined by many variables, most of which are still not well understood. WHO has now applied the Delphi method to project HIV prevalence from the year 1988 to mid-2000. This method attempts to improve the quality of the judgements and estimates for relatively uncertain issues by the systematic use of knowledgeable "experts". The mean value of the Delphi projections for HIV prevalence in the year 2000 is between 3 and 4 times the 1988 base estimate of 5.1 million; these projections have been used to obtain annual estimates of adult AIDS cases up to the year 2000. Coordinated HIV/AIDS prevention and control programmes are considered by the Delphi participants to be potentially capable of preventing almost half of the new HIV infections that would otherwise occur between 1988 and the year 2000. However, more than half of the approximately 5 million AIDS cases which are projected for the next decade will occur despite the most rigorous and effective HIV/AIDS prevention efforts since these AIDS cases will develop in persons whose HIV infection was acquired prior to 1989. The Delphi projections of HIV infection and AIDS cases derived from the WHO projection model need to be periodically reviewed and modified as additional data become available. These projections should be viewed as the first of many attempts to develop estimates for planning strategies to combat the HIV/AIDS pandemic in the 1990s.

The present and future course of the AIDS epidemic in Côte d'Ivoire.

An assessment of the current and future mortality and morbidity from acquired immunodeficiency syndrome (AIDS) in Côte d'Ivoire was made using the results of the 1989 national survey of the prevalence of human immunodeficiency (HIV) infection in the country and the AIDS projection model developed by WHO. For 1989 it was estimated that about 25,000 AIDS cases in adults and children had occurred, although the total number of cases reported for 1989 (up to 1 July 1991) was about 13% (1:6.9) of this estimated total. It is projected that by 1994 in Côte d'Ivoire the cumulative number of cases of AIDS in adults will be 89,000, and that for infants and children the corresponding number will be 41,000. It was also projected that about 371,000 uninfected children will have been born to HIV-infected mothers in Côte d'Ivoire by 1994 and that many of these children will have been orphaned by the deaths of their mothers from AIDS.

Strategies for laboratory HIV testing: an examination of alternative approaches not requiring Western blot.

Advances in laboratory tests for antibodies to human immunodeficiency virus (HIV) have permitted the development of alternative HIV testing strategies that do not require use of the Western blot approach. Three strategies are proposed. In strategy I, sera are tested for HIV antibody using an enzyme-linked immunosorbent assay (ELISA)/rapid/simple (ERS) test; in strategy II, sera reactive in an initial ERS test are retested using a second ERS test; strategy III involves retesting with a third ERS test all sera reactive in two previous ERS tests. Where the objective is identification of asymptomatic HIV-infected individuals, strategy III is proposed where HIV prevalences in the study population are < or = 10%, and strategy II at prevalences > 10%. Strategy II is recommended where the diagnosis of HIV-related disease requires HIV testing. For serosurveillance, strategy II is recommended if the prevalence is < or = 10%, and strategy I if the prevalences are > 10%. Use of strategy I is recommended for transfusion and transplantation safety, at any prevalence. Lower-cost laboratory HIV testing will permit such testing to become more widely available.

PIP: Testing of sera for antibodies to HIV typically involves screening with enzyme-linked immunosorbent assays (ELISA) and subsequent confirmation with Western blot (WB). Western blot testing, however, is relatively expensive and technically demanding. Recent technological advances have produced tests which provide results equivalent in accuracy to those obtained by WB. These include new ELISA tests, simple tests, and rapid tests. Simple tests are those which are easily learned and require no additional equipment or instrumentation, while rapid tests yield results in 30 minutes or less. The lower cost of these methods will allow HIV testing to become more widely available. The authors propose alternative laboratory HIV testing strategies based upon these newer ELISA/rapid/simple tests (ERS). Strategy 1 tests sera for HIV antibody using ERS tests. Strategy 2 retests sera reactive to initial ERS, and strategy 3 simply retests reactive sera a third time with ERS tests. Strategy 1 is recommended for transfusion and transplantation safety at any prevalence of HIV infection is selected populations. Strategy 1 is also recommended for serosurveillance in study populations where the prevalence of HIV infection is greater than 10%, but strategy 2 is recommend where prevalence are less than or equal to 10%. Strategy 2 is generally recommended when diagnosis of HIV-related disease requires HIV testing. Finally, strategy 3 is proposed to identify asymptomatic HIV-infected individuals where HIV prevalence in the study population are less than or equal to 10%, but strategy 2 will suffice where prevalence are greater than 10%.