The global distribution of actinomycetoma and eumycetoma

Background: Mycetoma, a chronic infection of the skin and underlying structures, affects those with a close relationship to the land, often in resource-poor areas of the world. Whether caused by any one of a variety of fungus or bacteria, mycetoma causes significant disability and mortality. Acknowledged as a neglected tropical disease (NTD) by the World Health Organization (WHO) in 2016, mycetoma is susceptible to being misunderstood, misdiagnosed, and mismanaged. In an effort to shift the balance in favor of recognition and effective treatment, sound epidemiological understanding is required. Methods and findings: In this paper, a literature review of case reports and series (332 papers in total) is presented as three maps. We identified 19,494 cases dating from 1876 to 2019, with cases contracted in 102 countries. The first map shows where mycetoma has ever been reported, the second shows how many cases have been reported, and the third shows the ratio of eumycetoma (fungal) to actinomycetoma (bacterial). Most cases are found in Mexico, India, and Sudan, where mycetoma is studied rigorously. We identified emergence of new geographical loci, including the United States, Venezuela, Italy, China, and Australia. Notably, mycetoma is reported far outside the tropics. In the Americas, bacterial forms dominate, whereas, in Africa and Asia, the picture is more varied. Conclusions: With better understanding of the epidemiology of mycetoma, more can be done to direct education, preventive measures, and treatment to at-risk areas, enabling a reduction in disease burden. Author summary: Mycetoma is an ancient and misunderstood chronic disease. Affecting the skin and subcutaneous structures, infection often occurs in the feet of land laborers and can be caused by several otherwise rare human pathogens. Traditionally seen as a tropical disease, it affects those in resource-poor regions. The best methods of diagnosis are rarely available in these areas; late diagnosis increases the need for invasive surgical treatment. Available medical treatment can be prohibitively expensive. Early diagnosis and identification of the causative agent is necessary for effective treatment. For this paper, a literature review was undertaken to find all published cases of mycetoma linked to a location and the data used to create three maps. The maps show where mycetoma has ever been reported, how many cases have been reported, and what kind of microorganism was present. We included 19,494 cases, most of which occurred in Mexico, Sudan, and India. Notably, some cases arose far outside the tropics. In the Americas, most cases are bacterial; elsewhere, the picture is more varied. Many gaps remain in the epidemiological study of mycetoma, but this paper aims to shed light on the significant reach of the disease, with a view to increasing its visibility on the global stage and, therefore, the scope for reducing the burden of this neglected tropical disease.