Blood tests designed to detect active TB are inaccurate and should be banned, the World Health Organization has said. More than two million such tests are carried out annually, but the WHO says they are unethical and lead to misdiagnosis and the mistreatment of patients.
The organisation's review of these tuberculosis test kits says they give wrong results in around 50% of cases. The kits are mainly sold in the developing world. However, most of the 18 kits on the market are produced in Europe and North America.
According to Dr Mario Raviglone, the director of the WHO Stop TB Department, the tests must be banned.
He said: "A blood test for diagnosing active TB disease is bad practice. Tests are inconsistent, imprecise and put patients' lives in danger." The tests work by detecting antibodies or antigens in the blood that are produced in response to the bacterium.
But some of these commercial tests have what's called "low sensitivity" which leads to large numbers of patients being told they do not have TB when they do.
Dr Karen Weyer, who is also from the WHO Stop TB department, added: "The evidence we reviewed over the past couple of months shows that one in two patients will be wrongly diagnosed, either [as] false negative or false positive.
