Darfur is headline news – but actually, the worst humanitarian crisis in the world today is in southern Africa. I mean it. While the devastating effects of the three-year drought now appear to be receding, southern Africa is still crippled by a blight of cataclysmic proportions – the HIV/AIDS pandemic.So far, around a million people have died. This is the tip of the iceberg: with as many as one in three adults in some countries infected with the HIV virus, the deaths can only increase. There are already 11 million AIDS orphans in southern Africa; by 2010, this number is expected to swell to 20m. Imagine every child under five in France, Germany, Italy, Poland, Spain and the United Kingdom losing their parents and you begin to get the picture.One of the worst aspects of HIV/AIDS is that it hits people at the most productive stage of their lives. Southern Africa is now losing teachers, doctors and civil servants at a faster rate than it can train them. The effect this has on social services is obviously devastating. In Africa as a whole, seven million farmers have so far died of AIDS – a much more lethal blow to agricultural production than any drought.Horrific as these statistics are, they do not seem to impress donors as much as the short-term, high-profile crises caused by conflict or natural disasters. There is, for understandable reasons, something of a fire-brigade mentality among donors. A big conflagration – such as Darfur – attracts generous donations. But getting funds for a long, smouldering, but far more destructive fire is a considerably more challenging task.So why is this so important for WFP? Because food aid can make a huge difference. For most people living with HIV/AIDS, drugs are still not available or affordable. But in the battle against HIV/AIDS, good nutrition can prolong their lives and keep them active and producing. And even for those fortunate enough to have access to anti-retroviral drugs, the medicine works better for the well nourished.There is also the fact that even in areas with the highest HIV prevalence, the vast majority of children between the ages of five and 15 are free of the virus. We need to do everything in our power to keep them that way. And while scientists continue to search for a vaccine and a cure for AIDS, the best hope we currently have is to keep children in school as long as possible. A recent World Bank study showed that young people with little or no education were twice as likely to contract HIV as those with a primary school education. The study also found that in comparison to children who do not go to school, those with an education were more likely to respond to HIV prevention campaigns and thus more likely to change behaviour that puts them at risk of contracting HIV. This is not to say that it is not serious – I saw for myself the horrendous plight of some two million people forced out of their homes, their livelihoods destroyed, women raped and whole families butchered. This dreadful injustice has rightly attracted the attention of the international press and world leaders.And WFP is there. So far, we are trucking and airlifting food aid to some 300,000 internally displaced people in the Darfur region and more than 100,000 refugees across the border in Chad. There is, unfortunately, a tendency in some quarters to see Africa’s struggle with HIV/AIDS as “not our problem”. But we may soon encounter what amounts to societal meltdown. You can already see it in rural areas whose small communities are being abandoned and fields lie fallow. Children are raising other children and they are all lost and hungry.I therefore have one crucial message to our already generous donors and in particular to the newly expanded and booming European Union: thank you for the big donations for the emergencies that we all see on the evening news. But it is even more important to invest now in warding off this millennium’s most deadly scourge, before it is too late.James Morris is the executive director of the United Nations World Food Programme and the UN secretary-general’s special envoy for southern Africa.