When it comes to public health investment there are few better ethical philosophies than utilitarianism: the greatest amount of happiness for the greatest amount of people. This remains more or less the defining cause in liberal democracies; a consistent guiding light.

So why do we not expect the same from our global prioritisation of public health? Somewhere along the way AIDS seems to have made some people lose sight of this utilitarian aim. 

United Nations: 'HIV/AIDS is the deadliest epidemic of our time. Over 22 million people have already lost their lives and more than 42 million are currently living with HIV/AIDS. Even if a vaccine for HIV were discovered today, over 40 million people would still die prematurely due to AIDS. In many countries, especially in Africa and the hardest-hit countries such as Botswana, Swaziland and Zimbabwe, the AIDS epidemic has spread rapidly, leaving illness, death, poverty and misery in its wake. In other countries the disease is still in its early stages. Notably, HIV/AIDS has now taken hold in the most populous countries of the world—the number of people infected with HIV has reached one million in China and six million in India; the destructive effects of the epidemic are already beginning to be felt in those countries.' (Source: 'The Impact of Aids, 2003') 

The deadliest epidemic of our time? This is a big claim. And also one that is difficult to accept. It relegates more pressing problems of sanitation and insect born diseases that kill much to second place. 

This is not to trivialise AIDS by any means. It is a very real disease of modern times and deserves a good deal of attention. On current progress, or rather lack of progress, by 2010 the world will contain nearly 100 millions having either HIV or AIDS. Three decades after first appearing AIDS will have infected around 1% of all humans.

But in the grander scheme of things this still means close to 99% of the world's population live without AIDS. Meanwhile water-borne diseases reign supreme amongst the silent assassins. This exposes close to 1-in-3 of all humans to risk and kills tens of millions through a miscellany of 'other diseases'.

Malaria adds another zero to the problem of AIDS. Whereas 40 million are infected by AIDS after three decades 400 million suffer from malaria annually. This is particularly bad amongst youngsters. Like AIDS malaria kills approximately 3 million per year (although it is much less mortal than it was). Yet the global fight against malaria receives a fraction of the resources allocated to AIDS. As noted by The Economist: "Every year malaria kills well over 1m people. The world now spends $400m a year on fighting malaria in poor places — much of that from one donor alone, the Gates Foundation — compared with almost $5 billion on AIDS." So malaria gets around 1% of the resources AIDS gets (US$400 million is under 1% of US$5 billion). 

Poverty. This is so brutal it is difficult to know where to start. One example of problem living conditions caused by poverty is domestic fires. This was reported by the BBC thus: "Thick acrid smoke rising from stoves and fires inside homes causes around 1.6m deaths a year in developing countries... The US Environmental Protection Agency has announced $1.3m funding for 11 pilot projects to seek ways to reduce people's exposure to indoor air pollution." So already one small area of poverty is killing almost half of all AIDS victims.  

Sleeping sickness is as prevalent as AIDS. Although it kills fewer it is economically debilitating. Chagas disease (excessive inflammation and weakening of internal organs) exposes significant parts of Latin America to risk but the world seems to ignore it. 

It gets more worrying when considering cost. AIDS is far more expensive to fight on a per capita basis. Some estimate that to keep one AIDS victim on anti-retroviral drugs costs as much as US$200 per person per year. Yet with a tiny proportion of that (something in the order of US$1 per person per year) much of the other big killers mentioned could be curtailed. This is especially so for water-borne diseases and malaria.

So why does AIDS get so much attention? There are two key answers and neither reflect well on the west. First, AIDS is one of the few diseases where infection visibly impacts rich and poor countries. AIDS is a rich country disease as much as a poor-country disease. The really big killers listed above are mostly confined in poor countries. Malaria, leprosy, river blindness, fatal diarrhoea, guinea worms and trachoma are obviously foreign problems to rich thinking. 

Consider polio. This has many similarities to AIDS in that it is, or was, a disease also affecting the west. Fifteen years ago there were over 300,000 cases of polio worldwide. Last year, and after US$3billion in investment, there were fewer than a thousand cases. Nearly eradicating polio is one of the great successes of the industrial age but we should be clear that it arose in large measure because polio was a disease that also afflicted the west.  

AIDS is also a chance to influence moraliy. Of all the killers in poor countries AIDS is the only disease that can be linked to the twin immoralities (in some eyes) of sexual promiscuity and drug taking. Malaria and water-borne diseases by contrast are indiscriminate.  

Background #3: Global infections/at risk populations by disease

Water-borne parasites: 2,000,000,000
Trachoma (blindness): 150,000,000
Chagas disease: 100,000,000
Sleeping sickness: 60,000,000
AIDS: 40,000,000
Leprosy: 750,000

Source: Adapted from Molyneux, The Lancet

Background #4: Bill Gates in 2007 (three years after this article first appeared)

‘The world has known about malaria for a long time. In the early 1900s, Nobel Prizes were given for advances in understanding the malaria parasite and how it was transmitted. But 100 years later malaria is setting records, infecting more than 400 million people every year, killing over a million people every year. That's more than 2,000 children every day. In 1999 the Gates Foundation gave $50 million to malaria research, and I was told that we had just doubled the amount of private money going to fight that disease. And I thought, That's the worst thing I've ever heard, that just can't be right.' More...