11/12/2025
Data from Zambart-Led Studies Show that Portable GeneXpert, CAD X-Rays, and Community Outreach Significantly Boost Early TB Detection
Zambart, together with regional and international collaborators, has been leading two pioneering multi-country studies aimed at transforming community-based tuberculosis (TB) detection in high-burden African settings. The findings from these studies were presented yesterday during a dissemination meeting held at Kanyama Level 1 General Hospital.
Conducted in peri-urban settlements across Lusaka in Zambia, Cape Town in South Africa, Harare in Zimbabwe, and Maputo in Mozambique, the XACT-3 and XACT-19 studies focused on densely populated communities characterised by overcrowding, high TB prevalence, and limited access to timely diagnostic services. Both projects explored innovative combinations of portable molecular diagnostics, digital chest X-ray technology, and computer-assisted detection (CAD) tools to improve early TB identification and accelerate access to treatment.
XACT-3 was designed as a randomised controlled trial comparing point-of-care (POC) GeneXpert testing using portable devices in mobile clinics with traditional centralized laboratory testing where sputum samples are transported to fixed facilities. The study assessed whether decentralizing molecular testing to the community level—using minimally trained health workers—could shorten diagnostic delays, reduce pretreatment loss-to-follow-up, and identify individuals who would otherwise go undiagnosed. It also integrated cough aerosol sampling and CAD X-rays to assess infectiousness and disease extent. The results were encouraging: 122 microbiologically confirmed TB cases were identified, and although the TB positivity rates were similar between the POC and centralized arms, point-of-care testing reduced the time to treatment initiation from eight days to just three.
This significant reduction demonstrated the value of bringing testing directly to communities and showed the feasibility of implementing such approaches at scale.
XACT-19 evaluated how digital chest X-ray with CAD, combined with molecular tools such as Xpert Ultra, could enhance active case finding for both TB and COVID-19. The study used a combination of randomised and observational designs to assess the performance of CAD-supported triage among high-risk individuals, asymptomatic community members, and participants presenting with COVID-19 symptoms.
At mid-point analysis, 3,237 participants had been screened and 118 were found to have microbiologically confirmed TB, yielding a positivity rate of 3.6% higher than that of many previous active case finding initiatives. CAD proved particularly valuable in improving the precision of screening and ensuring that Xpert Ultra tests were directed toward individuals most likely to have TB. The approach demonstrated strong potential for scalability, particularly in low-resource settings where the dual burden of TB and COVID-19 strains existing health systems.
Across both studies, more than 6,500 community members participated, making this one of the largest TB active case finding efforts of its kind in the region.
By combining rapid molecular diagnostics, digital imaging, and community outreach, the XACT-3 and XACT-19 studies highlight a future in which early TB detection is faster, more accessible, and more aligned with the realities of high-burden settings.
Taken together, the findings show that community-based TB screening is both effective and essential for closing the gap on undiagnosed TB. The use of CAD and GeneXpert technologies strengthens active case finding, and point-of-care testing significantly accelerates treatment initiation—reducing the period in which individuals can transmit the disease. These innovations offer scalable, evidence-based solutions that national TB programmes across the region can adapt and expand.
The success of the XACT-3 and XACT-19 studies marks an important step forward in developing approaches that can transform TB control across high-burden African communities in a quest to improve health for all.
London School of Hygiene & Tropical Medicine University of Cape Town Ministry of Health Zambia