Blood tests designed to detect active TB are unreliable and should be banned, according to the World Health Organisation.
The WHO’s review of tuberculosis blood test kits said that inaccurate results occur in 50% of cases. It recommends the use of molecular or microbiological tests.
Dr Mario Raviglone, the director of the WHO Stop TB Department, said that blood tests for TB are “inconsistent, imprecise and put patients’ lives in danger.”
Serological (blood) tests diagnose TB by detecting antibodies or antigens in the blood that are produced in response to the bacterium. But some of the commercial tests have low sensitivity, leading to a high proportion of ‘false negatives’ (patients being told they do not have TB when they do).
The kits are sold mainly in the developing world, and are used to carry out more than 2 million tests each year.
This is the first time the WHO has issued an explicitly negative recommendation against a technology that is widely used in TB treatment.
Tuberculosis kills 1.7 million people every year, and is the biggest cause of death of people living with HIV.