Information gathered from scientific literature shows that Buruli ulcer has been reported in 33 countries in Africa, the Americas, Asia and the Western Pacific. Most cases occur in tropical and subtropical regions except in Australia, China and Japan. Out of the 33 countries 15 regularly report data to WHO.
The majority of cases are reported from West and Central Africa, including Benin, Cameroon, Côte d’Ivoire, Democratic Republic of the Congo and Ghana. In recent years Australia has been reporting a higher number of cases.
In 2014, 12 of the 15 countries regularly reporting data to WHO reported nearly 2200 new cases, more than 50% less than 2009 when 5000 cases were reported. Except for a few countries, the number of cases has declined since 2010. The exact cause of decline is unknown.
Clinical and epidemiological characteristics of cases
The clinical and epidemiological aspects of cases vary considerably within and across different countries and settings.
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.