Hope for those co-infected with HIV/AIDS and TB

All Dr Gilles van Cutsem would like for Christmas is a painless way of testing children for tuberculosis (TB). The standard test used in Africa detects the TB bacillus in the sputum, but obtaining a sample is difficult, as children swallow sputum instead of spitting it. Doctors get the sputum by inserting a tube through the nose into the stomach of children as young as six months old. This test had also failed to detect TB in HIV-positive patients, despite the presence of the TB bacillus, said van Custem, who manages an HIV/AIDS and TB clinic for the international NGO, Medecins sans Frontieres (MSF), in Cape Town, South Africa. If TB is left untreated because of non-detection, patients can develop severe and fatal forms of the disease. "TB in HIV-positive patients kills faster," he told PlusNews. TB is a curable disease, yet it kills two million people every year, 99 percent of them in developing countries. Globally some 12 million people are co-infected with HIV/AIDS and TB, of whom two-thirds live in sub-Saharan Africa. As the single leading cause of death among people living with HIV/AIDS, TB occurs earlier than other opportunistic infections, progresses faster and is almost always fatal if untreated. But, according to the MSF Campaign for Access to Essential Medicines, the testing mechanisms the world uses to control TB are hopelessly inadequate, particularly when dealing with HIV/AIDS. The smear sputum microscopy test, for example, has been in use for 122 years because it is cheap, requires basic laboratory equipment and effectively detects active pulmonary TB, the most infectious form of the disease. Nevertheless, children and people living with HIV/AIDS are more likely to have extra-pulmonary and latent TB, which the test fails to pick up. Extra-pulmonary TB accounts for at least two out of 10 TB diagnoses among HIV-positive people. The screening test for latent TB, developed in 1890, is unreliable when used for people living with the virus. "HIV/AIDS is reshaping the TB epidemic completely," said Marta Darder, MSF campaign coordinator in South Africa. A study by the MSF campaign, 'Running out of breath? TB care in the 21st century' calls for a simple, field-adapted test that delivers reliable results in even the most resource-poor, AIDS-affected settings. Less than 20 percent of the about eight million predicted annual cases of tuberculosis are identified by the smear sputum test, but diagnosis based on this test is the cornerstone of the anti-TB strategy known as Directly Observed Treatment Short-course (DOTS), recommended by the World Health Organisation (WHO). "The limitation of smear microscopy complicates both prophylaxis and treatment" of TB in HIV-positive patients, says an MSF study based on its experience of treating TB in the context of HIV/AIDS and poverty. In 2003 MSF treated 20,000 new TB patients in 29 projects in 21 countries. One such project is the "Ubuntu" (humanity) clinic in Khayelitsha on the outskirts of Cape Town, run by Dr van Cutsem. Impoverished and crowded, Khayelitsha is an epicentre of the dual TB/AIDS epidemic. Any country with a rate of 250 TB cases per 100,000 inhabitants is considered high-burden - Khayelitsha's is five times higher than that global average. "It's a disaster; only prisons and mines have higher rates," van Cutsem told PlusNews. Biotech firms and research institutions have developed improved diagnostic tests, already in use in developed countries, but these are relatively expensive, and require trained technicians and proper laboratories. However, MSF has found that in one year's time, two of the new tests could be adapted to the poor infrastructure and training typical of TB-endemic countries: one detects active TB on the skin with the help of a protein and the other is a rapid media culture, but companies are reluctant to spend the US $5 million to $15 million that WHO estimates would be needed to adapt the tests to resource-poor settings. A glimmer of hope lies in the Foundation for Innovative New Diagnostics (FIND), launched in May 2003 with a US $30 million budget for the first five years, funded by Bill Gates. FIND has developed a database of all diagnostics in development, has produced performance guidelines and is conducting clinical trials. MSF is calling for a global emergency plan to speed up validation of promising new tests, prioritise development of diagnostic tools for resource-poor settings, and make them affordable. Then, hopefully, van Cutsem might see his wish come true before next Christmas.