Tuberculosis (TB) is one of the world's most lethal diseases, and is expected to kill almost 2 million people this year. But it has a relatively low public profile. Worse still, efforts to research, prevent and treat the disease are entangled in an unseemly rivalry with corresponding approaches to AIDS.

TB has been with us for centuries, and has probably already claimed many of the people in the West who are genetically susceptible to it. By far the greatest prevalence today is in Africa and India, where susceptibility to TB often goes hand-in-hand with HIV infection (see Nature Med. 13, 263; 2007 and

Yet the response to the march of the disease in poor countries has been patchy. The World Health Organization (WHO) has led a moderately successful effort to offer basic treatments to as many people as possible, using 40-year-old drugs of limited effectiveness. The US National Institute of Allergy and Infectious Diseases sponsors by far the world's largest TB research programme, and the Bill & Melinda Gates Foundation is making a determined push to reboot efforts to translate research into clinically useful drugs and vaccines.

However, all this activity is modest in relation to the scale of the problem. TB research programmes are estimated to be worth about $300 million worldwide — less than one-tenth of the amount devoted to AIDS. Important questions, including how to develop better ways of detecting the disease cheaply and reliably, and how to assess the effectiveness of new drug combinations, go unanswered.

But it isn't just the lack of funding that makes TB researchers feel like the poor relations in the global health family. Difficulties in working alongside the better-funded efforts to tackle AIDS permeate many aspects of TB prevention, treatment and research at all levels, from the clinics of South Africa's most impoverished townships to the headquarters of the WHO in Geneva.

Treatment for TB is commonly dispensed in developing countries through long-established public-health clinics, whereas AIDS treatment often comes through separate, dedicated facilities. This division does nothing for the patients suffering from both diseases.

As for research, there has been inadequate collaboration between the relatively small number of scientists who devote their careers to studying TB and the far larger community working on AIDS. Yet both groups could surely benefit from each other, especially with regard to improving their understanding of the interaction between the two diseases.

But it is perhaps at the bureaucratic level that this division is most pronounced. The offices dealing with AIDS and TB at the WHO, for example, have historically enjoyed a difficult relationship characterized by rivalry rather than cooperation.

Steps are being taken to improve this sorry state of affairs. Treatment is successfully being integrated on the ground in South Africa and elsewhere, usually one clinic at a time. Researchers from the two fields are working together to study 'immune reconstitution syndrome', a little-understood phenomenon that affects those taking drugs for both TB and AIDS. And at the WHO, outmoded blueprints for the diagnosis and treatment of TB are being revised, with the assistance of staff with backgrounds in HIV treatment. Thanks to the intervention of the Gates Foundation and others, drug and vaccine candidates for TB are entering trials at a reasonably healthy rate for the first time in decades.

There is an overriding need for greater collaboration between AIDS and TB prevention, treatment and research, and this should be implemented at the grass roots wherever possible. But this common-sense remedy isn't, on its own, going to overturn a deeply ingrained division that has taken shape over many years.

Global health provision only really changes when leadership is forthcoming, not just from international organizations but from governments, specifically those that are in a position to lead — in this case, those of the United States, the European Union, India and South Africa. World Tuberculosis Day on 24 March seeks to draw attention to the disease, and provides an opportunity for governments to do just that, by acknowledging the problem and stating what they intend to do about it.