The World Health Organization (WHO) will issue a recommendation against the use of widely available blood tests for the diagnosis of tuberculosis (TB) later this week. The warning—an unprecedented move for the organization—comes as a response to several studies that have found that the tests, which are commonly used in developing countries, produce too many false negatives and false positives to be considered reliable.
It is estimated that around one third of the world’s population is infected with Mycobacteria tuberculosis, but only around 5-10 percent of infected people develop the deadly respiratory disease. Currently, diagnostic methods in the United States and other developed countries consist of isolating and culturing the bacterium (known as the acid-fast smear test), as well as a nucleic acid amplification test for the bacterium’s DNA.
But in developing countries, there is a widespread and unregulated use of serodiagnostic kits, which detect antibodies against M. tuberculosis in the blood, often by organizations with financial motivation. “Many of these tests are used in the private-for-profit sector, charging poor people who do not understand the lack of value of the test,” Mario Raviglione, the director of WHO’s Stop TB department, told the Associated Press.