Geneva −− The World Health Organization, in collaboration with the Foundation for Innovative New Diagnostics, has started a thorough evaluation of an innovative diagnostic test developed by researchers at Harvard University that can lead to rapid confirmation of Buruli ulcer in a patient.
Initial results from recent field trials in Benin and Ghana show that the test can detect mycolactone, a toxin produced by the bacteria that causes tissue damage and leads to Buruli ulcer. The most important aspect of this new test – which is more sensitive than microscopy – is that it can be carried out by technicians with minimal training in district hospital laboratories.
The results are read within an hour.
The challenge to overcoming Buruli ulcer is early detection and diagnosis, prompting WHO to advocate the development of a rapid point-of-care diagnostic test over the past decade. In 2010, the researchers made a breakthrough by using boronate-assisted fluorescent thin-layer chromatography to selectively detect mycolactone when visualized with ultraviolet light. Further improvements have since optimized the method and the reading of results.
Clinical diagnosis of Buruli ulcer currently relies on well-trained, experienced health workers. Polymerase chain reaction – the most widely used diagnostic test because of its high sensitivity – can be done only in reference laboratories, remote from affected communities; results are available in a few weeks.
The disease
Buruli ulcer is a chronic debilitating infection of the skin and soft tissue caused by a bacterium, Mycobacterium ulcerans. The infection begins as a painless nodule, plaque or oedema and develops into an ulcer, destroying the skin and soft tissue and causing large ulcers usually on the legs or arms. Patients presenting at health facilities with advanced ulcerative stages pose a major problem; treatment is complex, involving surgery and skin grafting, and frequently results in long-term disability.
Given the late detection of cases, many patients were referred to hospitals by community health workers at district level; lengthy travel and costly hospitalization were major constraints.
Buruli ulcer has been reported in 33 countries in Africa, the Americas, Asia and the Western Pacific. Some countries in West and Central Africa – Benin, Cameroon, Côte d’Ivoire, Democratic Republic of the Congo and Ghana – report the majority of cases. Australia and Japan are major endemic countries outside Africa.
Since there is no knowledge of how Buruli ulcer is transmitted, preventive measures cannot be applied. Health education and active surveillance remain the cornerstone for control of the disease.
Progress
Ten years ago, treatment relied almost exclusively on surgery that involved extensive excision, skin grafting and, in some patients, amputation of limbs. Significant progress has been made over the past decade and treatment is straightforward if the disease is detected early. Advances in the development of rapid point-of-care diagnostics have enhanced prospects for management of the disease.