Transmission
The exact mode of transmission of Mycobacterium ulcerans (M. ulcerans) is still unclear. Buruli ulcer usually occurs near slow moving or stagnant bodies of water, where M. ulcerans is found in aquatic insects, molluscs, fish and the water itself. It is not clear how M. ulcerans is transmitted to humans.
Signs and symptoms
Buruli ulcer often starts as a painless swelling (nodule), a large painless area of induration (plaque) or a diffuse painless swelling of the legs, arms or face (oedema). The disease may progress with no pain or fever. Without treatment or sometimes during antibiotics treatment, the nodule, plaque or oedema will ulcerate within 4 weeks. Bone is occasionally affected, causing deformities.
The disease has been classified into three categories of severity: Category I, single small lesion (32%) less than 5 cm on diameter; Category II, non-ulcerative and ulcerative plaque and edematous forms between 5-15 cm (35%); and Category III lesions more than 15 cm in diameter including, disseminated and mixed forms such as, osteomyelitis and joint involvement, lesions at critical sites (head, breast, genitalia), (33%).
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. Health workers should be careful in the diagnosis of Buruli ulcer in patients with lower leg lesions to avoid confusion with other causes of ulceration such as diabetes, arterial and venous insufficiency lesion.