Most TB testing today relies on sputum samples coughed up from the lungs. This makes intuitive sense since pulmonary (or lung) TB is the most common form of TB and sputum provides testable samples straight from the scene of infection.
A major snag, however, is that children and some people living with HIV find it difficult or impossible to cough up the sputum needed for testing. The resulting delays or uncertainties in diagnosis often have knock-on effects on treatment.
The race is thus on to find TB tests that do not rely on sputum.
Blood, urine, and saliva are all candidates, as increasingly is stool. While all these have pros and cons and while the evidence base is still evolving, there seems to be a compelling case for the wider use of stool samples.
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