Tony Blair wants to "sort out" Africa. As this year's leader of the group of eight wealthiest nations he should start by focusing on the disaster that is Zimbabwe. One reason among many is that the diaspora of Zimbabweans into neighboring states is substantially worsening the Aids problem in southern Africa.

African leaders have been reluctant to act on Zimbabwe's politically induced humanitarian disaster but must intervene this year as their own populations are threatened with disease. And they need support from the international community, which is trying to combat the Aids pandemic.

Business as usual is no longer an option; if political stability is not returned to Zimbabwe soon and the refugee population doesn't go home then all Aids efforts in the region may become worthless.

Robert Mugabe, the only president Zimbabwe has ever known, is the last hero of the African struggle for independence still clinging to power. Adored by most Africans for the past, he is despised by many of his countrymen for the present. He came to power in 1980 and has ruled with an iron fist ever since.

The slide into despotism has halved the value of the economy over the past five years, inflation is so rampant that bank notes are only printed on one side and some expired on December 31. More than 80 percent are unemployed; food production this year was less than half that in 2000 and is forecast to be only 15 percent of normal in 2005.

And, while the president says everything is fine, the World Food Program says that over five million people are short of food, out of a population of maybe 11m. It is simply impossible to know how many Zimbabweans have left the country and how many remain.

Much media coverage has focused on the 4,500 white farmers and their families who have fled Mugabe's reign of terror, but while this has probably lost the country 25 percent of foreign exchange earnings, the real danger to the region is the ill health of the black diaspora.

Twenty years ago, life expectancy in Zimbabwe was 58; in 2002 it was 33 and dropping. The official HIV/Aids rate in 2002 was about 27 percent (the third-highest in the world), but is probably much higher today. Further, Dr Mark Dixon of Mpilo Hospital in Bulawayo says that 70percent of the cases he sees have HIV.

A possible reason for this extraordinary number is the large amount of unprotected sex (usually rape) in Mugabe's youth camps. The president established these camps apparently to re-orientate the educational sector, but according to all the Zimbabweans I spoke with, including a couple who had escaped the camps, it was really to indoctrinate young men and women against the opposition party and white people.

The worst cases of Aids are tragic--sufferers have no drugs and no future. And since they are too sick to travel they will not seek treatment abroad. The only good thing about this is that they won't take the virus to other countries. But the mobile and generally healthy, if malnourished, youth leave if they possibly can. Sadly, this is exactly the age group which carries the highest HIV burden and they carry the virus wherever they go.

According to Amnesty International, Zimbabwean refugees are constantly abused in transit or wherever they end up, since they are not recognized as legitimate asylum seekers and hence live illegally doing whatever dangerous job they can get. No neighboring state acknowledges the despotism of the Mugabe regime, and so naturally doesn't accept economic migrants as political refugees.

An illegal and dangerous existence awaits the majority, with many women lured into prostitution. Some are lucky enough to reach the safe haven of places like Bishop Paul Verryn's church in downtown Johannesburg, where I met some of the 35 refugees who live and establish stalls selling wares to parishioners and passers-by. But for most of the estimated two to three million Zimbabweans in South Africa their existence is nasty and brutish, but not short enough to prevent transmission of HIV.

South Africa, with a population of 42 million, is perhaps big and rich enough to accommodate her Zimbabwean neighbors. Other countries are less well-placed. According to figures from various non-governmental organizations working in the region, neighboring Botswana now has probably more than 200,000 illegal Zimbabwean immigrants added to its native population of just over a million people.

Such an influx has caused a terrible strain, leading to conflict, rape and the possibility of increasing the HIV rate from its current and staggering 38percent. And it is not surprising that, as a result, President Festus Mogae of Botswana has been the most outspoken against the Mugabe regime.

While Mugabe continues to force his citizens to leave the country, efforts to control HIV in much of the entire southern African region will be undermined. It is time the international community acted on Zimbabwe by pressuring the region's leaders to act, since aid and trade deals matter to them even if they don't matter to Mugabe.

South Africa's President Mbeki could stop Mugabe in his tracks by turning off the electricity supply. But he won't until he feels real pressure to do so. Zimbabweans want to return home, but not while Mugabe is president.

Roger Bate is a visiting fellow AEI and a director of Africa Fighting Malaria.