TB or Not TB?

That’s been the question for nearly 150 years since Dr. Robert Koch identified the rod-shaped bacterium responsible for tuberculosis (TB). This serious respiratory disease is currently the world’s deadliest infectious disease, claiming over a million lives annually.

Interestingly, the most common method for diagnosing TB hasn’t changed much since the late 1800s, and it still involves phlegm.

“It’s a nasty substance,” remarks Adithya Cattamanchi, a pulmonologist at UC Irvine. “Nobody likes dealing with it—coughing it up isn’t pleasant. And for health workers, it’s tricky because it’s so thick.” Plus, some individuals like young children, the elderly, or those weakened by illness might struggle to produce enough phlegm.

Once collected, the phlegm is examined under a microscope for the TB bacteria. However, the accuracy of this test is questionable, as it can lead to false positives or, conversely, miss actual cases of TB about half the time.

“We have long sought to make TB diagnosis easier, cheaper, and quicker,” says Alfred Andama, a microbiologist from Makerere University in Uganda.

Last year, that search took a promising turn when the Chinese company Pluslife introduced a novel test called the MiniDock MTB. This innovative test works by analyzing either phlegm or a simple tongue swab, heating the sample, and scanning for DNA from the TB bacteria. It’s faster than traditional testing and portable enough for use in many settings.

“It’s more affordable, and processing swabs is a lot easier compared to using a microscope,” explains Cattamanchi. The device costs about $300, and each test runs between $3 to $4.

Moreover, a recent study by Cattamanchi, Andama, and others published in the New England Journal of Medicine indicates that the new test is accurate and meets World Health Organization (WHO) standards, regardless of whether it uses phlegm or a tongue swab.

They enrolled nearly 1,400 patients with TB symptoms across health centers in seven African and Asian nations, including Uganda. “What we hope is that this allows more people to access high-quality TB testing,” Cattamanchi expresses. This could lead to quicker care and help limit the transmission of TB.

The Perils of Traditional Testing

Cattamanchi has worked at health facilities across central and eastern Uganda and has witnessed firsthand how convoluted the path can be for patients seeking a TB diagnosis. It can turn into a lengthy ordeal.

“They might first visit a pharmacy,” he explains, “receiving some medication for a cough or fever. But symptoms often return or worsen.”

Additionally, certain healthcare facilities lack TB testing capabilities, leading many patients to visit multiple centers before they find one that offers testing. “Many people make three, four, or five visits,” adds Cattamanchi.

Delays and misdiagnoses can further complicate matters. “When patients go undiagnosed, they often grow more ill, and they risk spreading the disease,” notes Andama. Early diagnosis, which leads to prompt treatment, is essential, making the introduction of the MiniDock MTB especially significant.

This new test emerged from an innovation surge during the pandemic, when efforts to develop swab-based COVID-19 testing saw significant advancements.

Accurate and Easy to Use

Andama holds optimistic views about the implications of this new testing method. “Most patients suspected of having TB could access testing,” he points out. Early detection and treatment can drastically improve patient outcomes.

Lucica Ditiu from the U.N.’s Stop TB Partnership, who wasn’t part of the study, shares the enthusiasm. “There’s quite a buzz around this,” she says, although she notes two important caveats.

First, the new test seems effective primarily for patients who have had TB for a while but may not catch early cases when the bacterial load is lower. “It might require further improvement for that,” she explains.

Second, the MiniDock MTB doesn’t differentiate between regular TB and drug-resistant varieties, a distinction that still necessitates additional testing to determine the appropriate treatment.

However, catching and treating TB promptly does help reduce the chances of the disease developing resistance. Cattamanchi acknowledges that there’s a long road ahead, but he believes this test marks substantial progress.

“Honestly, my hope is that after 150 years, we can finally move beyond using a microscope for diagnosis,” he says. “I think we’re closer to achieving that than ever before.”