Full project title:
Evaluation of Mycobacterium leprae specific RPA assay incorporated in mobile suitcase lab for rapid diagnosis of clinical and sub-clinical leprosy in Bangladesh
Project coordination
International centre for diarrhoeal disease research, Bangladesh(icddr,b)
Partners
Damien Foundation, Bangladesh
University of Leipzig
Kumasi centre for Collaborative Research in Tropical Medicine
Dept. of Pharmacology, Institute of Post Graduate Medical Education and Research, India
Bankura Sammilani Medical College And Hospital
Aim: This study addressed the following question: What are the diagnostic/clinical sensitivity and specificity of ML-RPA assay toward detection of leprosy using a mobile suitcase laboratory platform?
Final project summary:
Leprosy is a contagious infectious disease caused by Mycobacterium leprae and remains one of the leading causes of disability among communicable diseases. Early diagnosis is essential to ensure timely treatment, prevent complications, and reduce the risk of transmission to family members and other close contacts, who are at the highest risk of infection. Reliable and accessible diagnostic tools are therefore critical for improving patient outcomes and supporting leprosy control efforts.
This project aimed to evaluate a new molecular diagnostic test known as the M. leprae Recombinase-Aided Amplification (ML-RAA) assay. Designed for use in a portable "suitcase laboratory," the test was intended to be simple, rapid, field-friendly, and affordable, making it suitable for use in low-resource settings. The goal was to determine whether this technology could accurately detect leprosy in patients and their household contacts, allowing earlier diagnosis closer to the point of care.
Prior laboratory studies had shown that the ML-RAA assay performed well when tested on cultured M. leprae DNA. In this project, the assay was evaluated under real-world conditions in Bangladesh using samples collected from people affected by leprosy and their household contacts. Its performance was compared with that of real-time polymerase chain reaction (PCR), which is currently one of the most sensitive laboratory methods available for detecting M. leprae. The study also assessed the feasibility of using a portable point-of-care PCR platform, the MyGo Mini PCR system, with the same samples.
The findings showed that, although the ML-RAA assay was promising in principle, it did not yet achieve the level of sensitivity required for routine diagnosis of leprosy in field settings. As a result, the test is not currently considered ready for use as a point-of-care diagnostic tool.
In contrast, PCR testing performed on skin biopsy samples produced encouraging results and demonstrated good potential as a laboratory-based diagnostic approach. These findings confirm the value of molecular diagnostics for detecting leprosy but also highlight the challenges of developing a simple, highly accurate test that can be used outside specialised laboratory settings.
The study underscores the need for continued research into new diagnostic technologies that can overcome the sensitivity limitations observed in current field-based methods. Future work should focus not only on improving molecular testing platforms but also on developing more sensitive, non-invasive sample collection methods. Approaches such as improved nasal swab techniques and novel serological biomarkers may help make leprosy diagnosis easier, more accurate, and more accessible.