A power struggle between scientists in the HIV and tuberculosis communities is undermining the fight against both diseases, according to a report in the latest issue of Nature Medicine.

As HIV infection rates continue to rise and TB experts witness the alarming spread of extensively drug-resistant TB, or XDR-TB, the two research communities are failing to combine forces against what is effectively a dual epidemic in many parts of the developing world, the journal warns.

It notes that TB is the leading cause of death among those infected with HIV and, in some African countries, about 60% of those with TB are also HIV-positive. Despite this, HIV and TB physicians and researchers take radically difference approaches - and cannot even agree on whether or not serious side-effects exist to the treatments they provide.

Co-operation is important because there are serious drug interactions between HIV and TB medicines. The key TB drug rifampicin interferes with some non-nucleoside reverse transcriptase inhibitors and some protease inhibitors, for example.

New IRIS syndrome uncovered

But worse, the journal reports that doctors are also finding a deadly new syndrome called IRIS (immune reconstitution inflammatory syndrome), in TB patients who receive anti-HIV medication. In most TB patients who also have HIV, anti-retrovirals reduce the severity of their TB symptoms by strengthening their immune systems.

However, experts such as Professor Robert Wilkinson of the University of Cape Town note that in a significant minority – around 20% – IRIS develops. Victims develop dreadful stomach abscesses and brain lesions and one in seven dies. “Nobody knows how to deal with it,” Prof Wilkinson said.

However, Dr Paul Nunn of the WHO’s Stop TB programme is more dismissive. “This is what you find when you talk to academic researchers whose job it is to go and look for problems,” he said, adding that IRIS had yet to be properly defined either clinically or in terms of its global impact.

Dr Richard Chaisson, director of the Center for TB Research at Johns Hopkins University, and former head of the university’s HIV/AIDs programme said the division between the HIV and TB communities was real – and damaging. “I work in both and I find it very frustrating. HIV people think TB people are dull, out of date and they don’t read published literature. TB people think HIV people can’t see beyond individuals to the community,” he said.

Dr Chaisson added that urgent action was needed to halt the “potentially catastrophic” spread of XDR-TB in which the infection was resistant to all first and second line antibiotics. In the same issue of Nature Medicine, Dr Ann Ginsberg and Dr Melvin Spiegelman of the Global Alliance for TB Drug Development in New York, discuss the scientific challenges to TB drug development and how they might be overcome.

And Dr Steven Reid, of the CD4 Initiative Project at Imperial College London, describes a new project, funded by an $8.6 million grant from the Bill and Melinda Gates Foundation, that aims to develop a cheap, finger-prick CD4 counter for use in the developing world within four years.