Tuberculosis

Updated 17 November 2017

New test may soon be available for diagnosing TB in kids

One of the reasons why TB causes so many deaths in children is because it's often misdiagnosed as pneumonia or meningitis.

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Two in 10, of the one million children with tuberculosis (TB) globally, die each year.

Speaking from the Union World Conference on Lung Health that took place in Mexico earlier this month, Dr Jeffery Starke said a staggering 96% of these deaths are in children who never received anti-TB drugs because the disease is very difficult to diagnose in kids.

A much-needed solution

An international paediatric TB expert, based at the Texas Children’s Hospital in the United States, he said the largely preventable and treatable disease causes so many deaths in children because it is often misdiagnosed as pneumonia or meningitis.

But new research coming out of the University of Cape Town (UCT), presented at the conference, may provide a much-needed solution.

TB is usually diagnosed using sputum samples: mucous coughed up from the lungs. But children often don’t have the force to cough such samples up and may be subjected to very “invasive” diagnostic methods, if at all, said Dr Paula Fujiwara, scientific director for the Union Against Tuberculosis and Lung Disease.

These can include a technique called gastric lavage where a tube is inserted through the nose and fed down to the stomach of the child to extract the contents, which are then sent to a lab to test for TB.

Tissue from the tongue

Three consecutive samples are ideally needed for a correct diagnosis, requiring three repeat trips to a health facility or for the patient to be admitted – which is labour intensive and costly to both patients and their families as well as the health system.

But for the first time, scientists are investigating whether tissue from the oral cavity, including from the cheeks tongue and gums can be used to successfully diagnose TB.

Researchers from UCT and the Tuberculosis Vaccine Initiative found that tissue from the tongue was the most sensitive. They are currently involved in phase two of a trial which aims to enrol 275 patients in the Western Cape to test if these samples can successfully be used to diagnose TB – especially for patients who can’t or find it difficult to produce sputum.

So far they have “promising” results for 49 samples from TB patients, 45 of which have tested positive in the laboratory using the oral swab method, translating into a sensitivity rate of 92%.

Rapid point-of-care tool

The implications for the success of this study are significant, particularly for children, according to Dr Angelique Luabeya, one of the trial’s lead researchers.

“It would be so easy to take a sample. My daughter could do it,” she said. “Patients themselves could even take a sample – it would be as simple as brushing your teeth and nobody does that for you.”

A small brush is used to scrape the inside of the mouth, after which the brush is sealed in a small container and sent to the laboratory for testing. In contrast, sputum testing requires a patient to cough up mucus, a process that, if not done under the right circumstances, can even aid transmission of the air-borne disease.

The “long-term” vision is to translate this diagnostic method into a rapid point-of-care tool that can be used by lay health workers without the need for laboratory testing.

Said Luabeya: “The beauty of it is it's so simple that we wonder why no-one's done it before.” – Health-e News.

Image credit: iStock