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AIDS diagnosis in developing nations

In developing countries it can be hard to make an accurate diagnosis of AIDS because of the lack of HIV testing facilities. The World Health Organisation proposed a clinical case definition, combining symptoms and signs common in AIDS (see table below). This has been used as the basis for AIDS statistics in many countries, but is inaccurate.

A study of hospital patients in Zaire showed that the case definition missed 31% of AIDS cases (definition not very sensitive), and 10% of those it identified as having AIDS were errors. The case definition misses people dying with severe HIV illnesses which do not fit the definition. For example, deaths from streptococcal pneumonia are far more common in those with HIV, yet such deaths were not included.

The commonest manifestations of AIDS in Africa are gross weight loss, chronic diarrhoea and chronic fever---the picture of `slim disease' as AIDS is known in African countries. However, it is difficult to exclude other causes for the same symptoms and signs.

Deaths from tuberculosis are another problem. TB is probably the most important infection in those with HIV in Africa. High rates of TB infection are found in those with HIV and the risk of death from TB is greatly increased in those with HIV. However, it is questionable whether all those with TB and HIV can be diagnosed as AIDS cases, since many have TB anyway. Many with TB lose weight and have fever as well as a cough. Therefore in the absence of HIV testing, many with advanced TB are likely to be labelled as AIDS cases using the WHO case definition.

In the light of all these problems, a revised case definition has been agreed. You may wonder how it is possible to be sure of the right diagnosis at all without laboratory facilities, and the answer is that it is very difficult.

Some have pounced on this difficulty to suggest that there is no AIDS in Africa at all. As we see elsewhere, this is not very convincing for two reasons. First, death rates have soared in the sexually-active age groups as HIV infection rates have risen. TB and other illnesses have been around and studied in detail for decades. Something new is happening. Secondly, when people with AIDS from African nations are cared for either in countries like the UK, or in very well-equipped hospitals nearer home, it is clear that there are gross abnormalities of their immune systems indicative of AIDS, with positive antibodies for HIV and damaged white cells.