The US Census Bureau report, to be published next month, shows that average life expectancy in Zimbabwe is expected to fall from 61 to 39 by the year 2010.

Zimbabwe is the country which has been worst hit by Aids, but the report shows the devastating toll of the disease across the continent.

According to the New Scientist, the report says that the average Kenyan will live 18 years less and the average Botswanan 22 years less because of Aids.

Joseph Malawa, director of population services in Zimbabwe tells the magazine; "We are living through a nightmare."

Status of women

Aids is prevalent in particular regions in Africa - mainly central, southern and east Africa.

In 1995, 60% of all HIV cases in Africa came from these regions, although they only account for about 15% of the continent's population.

More than 80% of people with Aids come from Africa. According to the United Nations Aids programme, UNAIDs, there are many reasons for this, including the status of women and their ability to negotiate safer sex, poverty and the high rate of sexually transmitted diseases in some countries.

UNAIDS says one in four people in Zimbabwe and Botswana have HIV - the highest prevalence in the world - and the figures are only a little lower for Kenya.

"This is what skews life expectancy," said a spokeswoman.

Southern Africa was initially thought not to have such a high rate as eastern and central Africa, but recent research shows the incidence is rising fast.

Mandela

On Friday, South Africa launched a new strategy to prevent the spread of HIV. Unfortunately, President Mandela was not on hand to launch the strategy due to sickness.

Nelson Mandela: missed the launch of South Africa's new Aids programme

UNAIDS says high profile campaigns backed by presidents and health ministries and aimed at the general population are necessary to slow the spread of HIV.

It believes the main reason for the spread in South Africa is thought to include cultural attitudes to sex, the high number of migrant workers and the fact that the government has tended to give other issues greater priority.

It says the country is also paying for its relatively high level of development. It has a high number of roads, which aids the spread of the disease.

Truckers who visit prostitutes are thought to be one of the major vectors of infection.

Early intervention

UNAIDS says early intervention can reduce the infection level. In Uganda, one of the African countries first struck by Aids, high profile government efforts have finally succeeded in lowering infection rates.

Prevention programmes have led to people having fewer sexual partners, using condoms more and postponing sex to a later age.

However, 10% of Ugandans are estimated to have the disease.

Aids prevention programmes in Uganda have had some success

In Senegal, early awareness campaigns and strong religious beliefs have combined to ensure that HIV levels have remained more or less constant.

But even in countries where levels of infection have been dropping, the impact of the disease is still likely to be devastating.

"Most epidemics strike the weak - the oldest and the youngest. But Aids strikes young adults - parents and workers. We do not know what the impact will be like in 30 or 40 years," said a UNAIDS spokeswoman.

Ignorance

The problem is compounded by ignorance of HIV status.

It reckons nine out of 10 infected people do not know they are carrying the disease. "And this is a conservative estimate," said a spokeswoman.

Asia is now looking likely to follow the African pattern.

Figures published on Wednesday show that 6,600 people have died of Aids in Cambodia this year.

Cambodia is the most effected country in the region. The health ministry estimates that 150,000 of the 11m Cambodians have HIV with 90% of infections caused by sexual intercourse.