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Aids Tuesday, 14 September, 1999, 17:46 GMT 18:46 UK
Aids statistics 'likely to be conservative'
Few people in Africa are tested for HIV
Aids is said to be the most deadly disease in Africa, but estimates of its spread are likely to err on the conservative side, say experts.

Because very few people in African countries are tested for HIV, figures are estimates based on tests carried out at a range of ante-natal clinics in a country, reflecting typical rural and urban areas.

Ante-natal clinics are used because they are a good indicator of sexual activity.

The figures are then compared with general population statistics for the15 to 49 age group and estimates are made for rural and urban areas.

Statistics for children are based on how many women are infected and the current birth rate in the country.

It is assumed 35% born to HIV positive mothers will be infected, 25% at birth and 10% through breastfeeding which is thought to be almost universal in most of sub-Saharan Africa.


In some areas, such as Uganda - the only country where the epidemic is thought to be have peaked, national surveillance programmes are good and figures are updated annually.

But in others, such as Ethiopia, information can be poor or almost non-existent.

Experts at the United Nations Aids programme (UNAIDS) say they rely on information from governments and much of this is out-of-date.

For example, Nigeria has not given any new data for the last three years.

Part of the problem has been external donors reluctance to pour money into improving surveillance because of fears about corruption.

However, attitudes are changing under the new government.

If there is no new data from a country, UNAIDS uses the old statistics and updates them based on new population figures.

This means its figures are likely to be an underestimate, particularly given that data on Nigeria and Ethiopia, two of the most populous countries on the continent, is poor.

Overall figures for Africa are also skewed by the fact that 80% of HIV cases occur in just eight countries.

Infection rates in some countries, particularly those in the north west which have less urbanisation and fewer transport links, are much lower than in the south and east. Religion may also play a part.

South Africa

Because of the lack of information in some countries, UNAIDS prefers to concentrate on places where it is more accurate.

South Africa's surveillance has improved greatly in recent months and the figures coming in show that HIV rates are soaring.

Some 21% of women aged 15 to 24 are thought to be infected.

"These are people who have only just become sexually active and so can show how fast the virus is spreading and whether public health campaigns are having an effect," said a UNAIDS spokesman.

The organisation says some people argue about the figures' accuracy, particularly on mortality since research shows many doctors fail to diagnose a death from Aids accurately.

Woman with Aids in Zambia
The accuracy of HIV figures vary across the continent
This might be for insurance reasons or because of the stigma associated with Aids.

Even the World Health Organization thought its mortality predictions were an overestimate.

But it changed its mind after it looked at the figures.

"There is not great data on other diseases like malaria and diarrhoea figures either.

"But Aids figures may be more accurate because it is a new problem and there is an urgent need for information," said the UNAIDS spokesman.

Health experts are investigating whether it might be possible to combine surveillance programmes to improve information collection, but one problem is that figures from ante-natal clinics may not be representative, for example, of the way malaria hits a population.

Aids Special Report
It is more likely to strike the elderly and the very young than young women.

UNAIDS says it would prefer to have bands of infection, ranging from high to low, rather than make percentage estimates.

"It doesn't make that much difference if we say 14% or 15% of the population is infected. It is still a big problem," said the spokesman.

See also:

02 Jul 99 | Aids
08 Jul 99 | Aids
08 Jul 99 | Aids
04 Oct 99 | Africa
04 Nov 99 | Aids
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