The WHO on Sunday said it will release a guidance later this week on widely used blood tests for tuberculosis (TB), warning “against using such tests for the infectious lung disease that affects some 14 million people worldwide” because they can produce incorrect results, the Associated Press/Washington Post reports.

“The tests are not reliable and a waste of money and time, putting proper care at risk,” Mario Raviglione, director of WHO’s Stop TB department, said, adding the tests “are in fact dangerous to patients, since some cases will not be detected and some will be called TB when in fact they do not have it.” According to the news agency, this “is the first time that WHO has issued a ‘negative’ policy, specifically counseling against the use of a particular method for diagnosing a disease” (7/17).