Easier TB Tasting with Oral Swabs

September 2025: Tuberculosis (TB) from primitive days, remains one of the world’s foremost infectious killers. According to the World Health Organization, more than 10 million people get sick with TB every year, yet an expected 40% of those cases go undiagnosed. A major challenge is that—collecting sputum especially in children, people living with HIV, or those without obvious lung symptoms is often difficult —cannot produce sputum, the thick mucus sample used in most TB tests.

Recent research suggests a promising alternative: mouth swabs (particularly tongue swabs or oral swabs) combined with molecular diagnostic tools. These methods could simplify and speed up TB testing, especially in low-resource settings. This article reviews the latest findings, what they mean, and what remains to be done.

What’s New: Tongue / Oral Swabs + CRISPR / Molecular Diagnostics

1. Tulane University – CRISPR-based “ActCRISPR-TB” test
   1. Researchers developed a CRISPR-Cas12a assay that works with tongue swabs, able to detect Mycobacterium tuberculosis DNA even at low concentrations.
   1. In a clinical evaluation, sensitivity for tongue swab samples was 74%, compared with 56% from traditional sputum tests, in the same set of specimens.
   1. For other sample types, the test showed high detection rates: ~93% for respiratory samples; ~83% for pediatric stool; and ~93% for adult spinal fluid.
   1. The test can give results in about 45 minutes, using a “one-pot” format (swab + reagents + a lateral flow strip) without extensive lab infrastructure.
2. University of Washington / University of Cape Town Study
   1. Funded by the Bill & Melinda Gates Foundation, this project is evaluating oral swabs (including tongue, gums, cheek) in ~245 adults and 100 children in South Africa.
   1. A previous smaller pilot found high accuracy: in that pilot, oral swabs correctly identified TB in 18 out of 20 adult TB-infected participants.
3. Other Supporting Studies
   1. A “tongue swab” method by UW researchers showed sensitivity of ~75% to 95% in symptomatic individuals (people showing TB symptoms), when compared with sputum analysis; but lower sensitivity in people who are asymptomatic (subclinical TB) (~34%).
   1. A meta-analysis of studies using oral swabs and molecular rapid diagnostic methods found pooled sensitivity of ~58.5% and specificity ~85.6%.
   1. Some recent studies (e.g. in Uganda) report tongue-swab qPCR sensitivity very high (above 90%) when compared to tools like Xpert MTB / microbiological reference methods.

What These Results Mean

• Non-aggressive sampling: Tongue or oral swabs are painless, simple, and generally much easier than to collect sputum, which many people were not able to produce or have difficulty producing. This system lowers barriers to diagnose.
• Faster improvement: Some of the new methods (like the CRISPR-based test) can give results in under an hour, without needing large labs. That’s critical for check-up in remote or under-resourced areas like rural areas or backward areas.
• Reaching missed populations: Children, people living with HIV, and those with extrapulmonary or subclinical TB are often under-diagnosed with under sputum-based testing rules. These new sampling methods may help find cases like this earlier and easier.

Limitations & What Remains to Be Solved

• Lower sensitivity in some groups / samples: While results are good in symptomatic people, sensitivity often drops among those with low bacterial load (e.g. early TB or subclinical infection). Some tongue-swab methods detect only ~30-40% in asymptomatic but infected individuals.
• Variation in technique matters: Sampling site (tongue, gums, cheek), how the swab is collected, the handling of the sample, reagent quality, etc., all affect results. Standardization is needed.
• False or negatives results still possible: Even with these upgraded methods, some TB cases detected via sputum are missed in tongue swab testing. Thus, a negative mouth swab result doesn’t always mean that a person is free from TB.
• Officially approval, cost, and placement: New tests must undergo large-scale authentication in various settings, get monitoring acceptance (e.g. from WHO), and be affordable and logistically possible.

Implications for Global TB Control

If fully validated and scaled, mouth swab-based TB testing could:

• Increase screening coverage, especially in remote or underserved communities.
• Facilitate earlier detection, reducing transmission.
• Reduce resource burden: fewer trained personnel, simpler collection, lower biosafety risk (sputum cough can generate aerosols).
• Be deployed in point-of-care settings (clinics, mobile units, community health workers) due to speed and simplicity.

Conclusion

The idea that a simple tongue or oral swab could significantly improve TB diagnosis is no longer science fiction—it’s becoming a real possibility. Recent studies, especially the new CRISPR-based ActCRISPR-TB, show that non-sputum methods are closing the gap in detection, speed, and accessibility.

Still, the journey isn’t over. Sensitivity in low-bacterial-load cases, consistency of collection technique, cost, and large-scale implementation remain challenges. But for many experts, this represents one of the most promising advances toward finding the “missing millions” of undiagnosed TB cases globally.