The cartographers of the "Aids map" of Africa have had a busy time over the past two decades. Although HIV, the virus which leads to Aids, can be traced back as early as the 1950s, it only really emerged as a public menace in the late 1970s and early 1980s.

Click here for a map of Greg Barrow's journey.

Central Africa was the early focus of the spread of HIV with the populations of Uganda, Tanzania, Rwanda, Burundi and the Democratic Republic of Congo (then Zaire), falling victim to the first major impact of the disease.

Botswana - Zimbabwe - Zambia

Almost 20 years later, the focus has shifted to southern Africa. In the period during which countries like Uganda have taken successful steps to contain HIV, public ignorance, slow government intervention, and social upheaval, have helped the virus to establish deep roots in the south of the continent.

Greg Barrow's journey through central-southern Africa

South Africa now has the fastest rate of new HIV infections in the world. Around one thousand five hundred people are newly infected with the virus every day in the continent's southern most nation.

In Zimbabwe, it's estimated that around one quarter of the population is HIV positive. Aids is becoming a disease which is likely to have a severe impact on the economy.

In Botswana, one of the wealthiest, and most stable nations in Africa, life expectancy is likely to drop dramatically over the next decade, from almost seventy years, to around forty; and in Zambia, there are grave social problems looming on the horizon, as the number of children orphaned by Aids, rises dramatically.

Watch Greg Barrow's report on his road trip through central Africa's Aids-hit countries

A journey through southern Africa from Johannesburg to Lusaka, takes you through the human landscape of Aids, from the orphanages of South Africa to the brothels at the truck stops in Botswana; from the factories which are struggling to cope with the deaths of Aids infected workers in Zimbabwe, to the rural hospitals of Zambia which are crammed full of dying patients.

Botswana

In Botswana's second city, Francistown, official figures collected on the basis of testing pregnant mothers at maternity clinics show that a staggering forty three per cent of the population is HIV positive.

But even this is seen as a conservative figure as many women suffering from HIV infection may find it difficult to conceive, and would not, therefore, show up on the statistics. Privately, health oficials believe that Francistown is a place where close to half the population is HIV positive.

Botswana, which is stil a very traditional, and conservative society has struggled to come to terms with the disease. Discussions of sexual practice remains an almost taboo subject, and while it is easy to spot Aids education posters, and stories about the disease in national newspapers, too little is being done to arrest the spread of HIV infection.

Francistown plays a particularly important role in the fate of the country and the whole region as it is the main truck stop on the route south from countries like Zambia, Zimbabwe and beyond. The young male truckdrivers gather here every night, crowding the bars and seedy nightclubs after a long drive south or north. "Are we going to eat tonight", they ask each other as they settle down for cool beer, and they're not referring to food.

People know about Aids, but they just don't seem prepared to do anything about it. "You have a few beers, and you forget," says Pula Masimegha, an off-duty soldier enjoying a night on the town, "You come here, you meet a babe, you go back to your house, the lights go out, and you forget. We just have to keep our fingers crossed." But keeping your fingers crossed in Francistown is about as dangerous as Russian roulette.

Prostitutes blame truck drivers for the spread of the disease

Some truck drivers like Abedniko Chinoi, have learnt the lesson the heard way. Last year, his co-driver died of Aids. Abedniko says he warned him about the dangers of casual sex, but his advice was rejected. "He was my senior," Abedniko says, "When I spoke to him, he became angry and asked me how I could know anything about it.

There are many other drivers who are HIV positive, and they know. They think they are already dead, and they don't care, so they just continue as before."

Ignorance is costing lives in Botswana. Aids has ripped through the middle class, killing the highly educated, and skilled workers. The country which has been blessed with political stability and economic growth for so long, is now facing a health crisis, which is spinning out of control.

Zimbabwe

Across the border in Zimbabwe, there is finally a sense of a clear and present danger. As HIV infection rates increase, Zimbabwe is becoming a country made up of the very old, and the very young.

A whole generation has been lost in between. The tragic phenomenon of child-headed households is becoming increasingly common, as young children grapple with the problems of caring for the remnants of the family once both parents are deceased.

Around 12-14% of the population of children has been orphaned, and as HIV infection continues to take its toll, this figure is expected to rise to around thirty per cent in the next twenty years.

The effects of losing all of those able-bodied, educated people, is making itself felt in the economy. Businesses like the Vitafoam mattress and furniture factory in Bulawayo, now train several staff for one job, and try to train people in as many skills as possible so that when a death occurs, or a worker is laid off sick because of HIV infection, the factory does not grind to a halt.

"It's a huge problem," says Taanda Marongwe, the factory manager, "We're not just facing the difficulty of keeping our factory running, but we are also burdened with the costs of caring for our staff, paying their hospital bills, and assisting them with funeral expenses."

When a death occurs on the factory floor, most businesses in Zimbabwe will pay for the coffin, and the transport costs of carrying the body of the deceased to his, or her, home village.

It's a longstanding tradition, built up in the days before Aids. Now that deaths are occurring with increasing frequency, its' become a tradition which eats into profit margins and puts a further strain on businesses which are already struggling to cope with the down turn in the Zimbabwean economy.

Even the non-governmental agencies which are contributing towards the fight against AIDS are struggling. They employ staff, who are potentially at risk from the disease.

Zambia

The UNICEF office in the Zambian capital, Lusaka has had to implement its own internal strategy to cope with the effects of HIV infection. Staff are educated about the disease, free condoms are distributed around the office, and managers have had to limit the number of days that workers are allowed to take off to attend funerals.

Some companies are making safe sex classes obligatory

One startling example of success in Zambia is the campaign to raise Aids awareness among remote rural communities. At the Salvation Army Mission in Chikankata, in southern Zambia, a revolutionary scheme is underway to bring traditional chiefs and village headmen on board strategies aimed at limiting HIV infection.

Without the assistance of these respected, and revered, community leaders, there is little chance of persuading local people to wake up to the dangers of Aids.

The Salvation Army community health projects in Chikankata have helped to change traditional practices which were jeopardising the whole survival of the surrounding communities.

In the past, when a mad died, his wife would be given over to one of his brothers. A ritual cleansing would take place at the funeral involving sexual intercourse between the wife and her deceased husband's brother.

If the husband had died of Aids - an increasingly likely scenario in Zambia - this traditional practice would afford an open route for the transmission of HIV infection. Now these rituals are dying out, as traditional leaders preach against them, and persuade the community that they are only helping the AIDS virus to thrive.

Unfortunately, the change has come too late for Chikankata. It used to be a thriving community which was known for cattle rearing.

Today the fields are empty and dry. "First of all we had drought, then the cows died from foot and mouth disease, and finally Aids arrived." says Elvis Simamvwa, director of the Salvation Army Mission, "Almost all of the able-bodied men have died of the disease, and there is nobody left to work the fields. It may be at least a decade before things recover and we go back to how it was in the old days."

The real tragedy of Aids in southern Africa is that it could have been controlled if governments, communities, and healthworkers had reacted earlier.

Now the countries of this region are being crippled by escalating health bills, businesses are buckling under the strain of losing workers, and the social landscape is being shattered. Africa, the continent which has the least resources to deal with the disease, is facing its biggest onslaught.

The World Health Organisation estimates that seven out of ten people who are newly infected with Aids come from sub-Saharan Africa, and more than eighty per cent of all deaths from disease since the epidemic started in the late 1970s, come from this continent.

The WHO believes that around thirty four million people in Africa are already infected with HIV. Only eleven and a half million have already died; the rest are either sick, or blissfully unaware of the deadly virus they carry in their blood.

The role of these carriers, holds a deathly grip on the future of generations of Africans, some still alive, but many who are yet to be born.