What is Buruli ulcer?
Buruli ulcer is caused by a germ, Mycobacterium ulcerans, that belongs to the same family of organisms that cause leprosy and tuberculosis. As M. ulcerans produces a toxin – mycolactone – which destroys tissue, infection leads to destruction of skin and soft tissue with large ulcers usually on the legs or arms. Patients who are not treated early suffer long-term functional disability. Early diagnosis and treatment are the only ways to minimize morbidity and prevent disability.
In Africa, about 48% of those affected are children under 15 years, whereas in Australia, 10% are children under 15 years and in Japan, 19% are children under 15 years. No significant difference exists between the rates of affected males and affected females.
Lesions frequently occur in the limbs: 35% on the upper limbs, 55% on the lower limbs, and 10% on the other parts of the body.
In terms of severity, the disease has been classified into three categories: Category I single small lesion (32%), Category II non-ulcerative and ulcerative plaque and oedematous forms (35%) and Category III disseminated and mixed forms such as osteitis, osteomyelitis, joint involvement (33%). In Australia and Japan, most lesions (>90%) are diagnosed in Category I.
In all countries, at least 70% of all cases are diagnosed in the ulceration stage.
The exact mode of transmission of M. ulcerans is still unknown.
Signs and symptoms
Buruli ulcer often starts as a painless swelling (nodule). It can also initially present as a large painless area of induration (plaque) or a diffuse painless swelling of the legs, arms or face (oedema). Local immunosuppressive properties of the mycolactone toxin enable the disease to progress with no pain and fever. Without treatment or sometimes during antibiotics treatment, the nodule, plaque or oedema will ulcerate within 4 weeks with the classical, undermined borders. Occasionally, bone is affected causing gross deformities.