Today is World TB Day and the theme for this year is “Yes! We can end TB!”.

Active case finding for tuberculosis (TB) in the community using a point of care, portable, battery-operated GeneXpert molecular test was superior to the routinely used same-day smear microscopy in detecting potentially infectious cases enabling quicker initiation of anti-tuberculosis treatment, according to the Xpert Active Case-finding Trial 2 (XACT-2) published recently in Nature Medicine.¹

In this study, researchers from the University of Cape Town and Stellenbosch University in South Africa and the London School of Hygiene and Tropical Medicine teamed up to screen 584 persons with symptoms of TB or HIV infection at a community-based mobile clinic in Cape Town, South Africa to find TB cases. Sixty-five percent of the participants were female, and the median age was 39 years. Two diagnostic methods were used for the screening: 296 individuals underwent same-day sputum smear microscopy performed at a nearby microscopy center (within a 5-km radius), while 288 were subjected to point of care molecular test (GeneXpert). Point-of-care HIV test and CD4 count was also offered.

The difference in the time to TB treatment initiation between the two groups was the primary objective of the study. It was found that treatment could be commenced as early as 8 days in the Xpert group compared to 41 days in the smear microscopy group. Overall, only 52% culture-positive TB cases were detected with Xpert. But, of note, 94.1% of the potentially infectious patients were detected with Xpert compared to just 23.5% patients detected with smear microscopy, which was the secondary aim of the study. The median time to start of treatment was shorter in the probably infectious patients in the Xpert group; 7 days vs 24 days, respectively.

Nearly 77% patients in the infectious group were still taking treatment at 60 days compared to 38.2% patients in the probably noninfectious group. All Xpert-positive patients were on treatment at 60 days, whereas less than half (46.5%) of the culture-positive patients were on treatment at 60 days. The study noted that "The number of at-risk people (with any TB symptom or HIV infected) who needed to be screened, to detect one case of active TB, was 18 for Xpert versus 99 for smear microscopy.”

This study has public health implications. It has for the first time demonstrated the feasibility of a mobile unit consisting of a low-cost minivan and portable battery-operated GeneXpert test in active case finding, particularly in resource-constrained TB-endemic countries. Not only was the point of care GeneXpert test able to rapidly detect TB in the at-risk people within 90 minutes compared to the same-day microscopy, but it also enabled rapid initiation of treatment. Significantly, Xpert could detect most patients who were probably infectious and therefore could spread the infection in the community. “These were patients who did not self-report to healthcare facilities”, write the authors.

India has the highest global burden of TB, including MDR TB. India has also set a target for complete elimination of TB by 2025. TB is a preventable and curable disease. Adoption of an active case finding approach in the community by using point of care molecular testing (GeneXpert) instead of passive case detection would help in the early detection of TB, especially infectious cases in endemic countries like India.

Early diagnosis means early and better treatment thereby breaking the chain of transmission. All contacts of patients with infectious TB should also be traced, screened and treated, if required. This will help us reach our goal of ending TB five years before the global target date of 2030. The Pradhan Mantri TB Mukt Bharat Abhiyaan was launched by the Hon’ble President of India last year who “urged the citizens to work collectively towards TB elimination in spirit of Jan Bhaagidari on a war footing.”

Reference

1. Aliasgar Esmail, et al. Comparison of two diagnostic intervention packages for community-based active case finding for tuberculosis: an open-label randomized controlled trial. Nat Med. 2023 Mar 9. doi: 10.1038/s41591-023-02247-1.