Academic journal article Bulletin of the World Health Organization

Global Surveillance and Forecasting of AIDS(*)

Academic journal article Bulletin of the World Health Organization

Global Surveillance and Forecasting of AIDS(*)

Article excerpt


At present (end of 1988), it is recognized that AIDS (acquired immunodeficiency syndrome) is a worldwide problem. However, after its identification in 1981, this pandemic was often characterized by denials and underestimation of its potential magnitude. It is now apparent that this unprecedented threat to global health is in its early stages, and its ultimate dimensions are difficult to estimate. From our current knowledge of AIDS, we consider that further spread is inevitable and the global situation will get much worse before it can be brought under effective control.

How many cases of AIDS can be expected to occur over the next five to ten years? Accurate estimates of these numbers are needed to effectively plan and direct both health care and public health programmes. However, accurate forecasting is not possible without a sound knowledge base about the past and present occurrence of AIDS. This article reviews the surveillance and global patterns of infections with the human immunodeficiency virus (HIV), the etiologic agent of AIDS, and provides some short-term forecasting of the HIV/AIDS situation in several major areas of the world.

Global surveillance

Worldwide AIDS surveillance is coordinated by a special unit in the Global Programme on AIDS (GPA) at the World Health Organization (WHO) in Geneva. Reports are received from Collaborating Centres, WHO Regional Offices, and ministries of health in countries. The accuracy and completeness of AIDS reporting vary markedly in different areas of the world. In most developed countries, it is believed that the majority of diagnosed cases are reported to national health authorities. In most developing countries, because of significant under-recognition, under-diagnosis, and under-reporting, it is believed that the majority of AIDS cases which have occurred have not been reported to WHO.

As of 31 December 1988, over 132 000 cases of AIDS have been reported to WHO by 143 countries (Table 1). The global AIDS surveillance data indicate that cases are occurring worldwide, and the numbers are increasing in all continents (Fig. 1). Large numbers of cases have been reported from North America, Latin America, Oceania, western Europe and Africa. However, because of very long reporting delays and incompleteness of reporting in many developing countries, WHO estimates that as of late 1988 the world total of AIDS cases which have occurred since the start of this pandemic is over 350 000.


Table 1: AIDS cases reported to WHO (as of 31 December 1988)

                       No. of countries reporting:
Continent   of cases    Zero cases   One or more

Africa       20 905          5            46
Americas     93 723          2            42
Asia            285         16            22
Europe       16 883          2            28
Oceania       1 180          9             5

Total       132 976         34           143

Global patterns

The large numbers of AIDS cases which are now being reported are due to HIV infections which began to be silently and extensively spread in the 1970s. The origin of HIV is not known with any certainty; in 1987 the World Health Assembly stated that HIV is a "naturally occurring retrovirus of undetermined geographic origin".

Since HIV infection precedes the development of AIDS by several years, an optimal understanding of the current patterns of AIDS must be based upon an analysis of both HIV sero-prevalence data as well as reported AIDS cases. From such analyses we have distinguished three broad, yet distinct patterns of AIDS. The explanation for the existence of these patterns includes the apparent date of HIV entry and/or period when HIV began to spread extensively in the population and details of sexual behaviour and intravenous (IV) drug use in the population. The three general patterns of AIDS are:

Pattern I: in these areas, HIV probably began to spread extensively in the late 1970s. …

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