Risk Profile for Transmission of Mycobacterium Ulcerans in Ghana

Abstract

Buruli ulcer disease (BU) is a skin disease caused by Mycobacterium ulcerans. Currently, Buruli ulcer has been reported in over 30 countries, the subtropical regions of Asia, in Latin America, in the Western Pacific region and in Eastern and Central Africa. Even though it has been reported in other continents, West Africa is the region most affected. It is one of the neglected tropical diseases and second commonest disease caused by Mycobacterium in Ghana and third globally. Suhum-Kraboa-Coltar, Akuapem South districts in the Eastern region and Ga West and Ga South districts of Greater Accra region are some of the districts affected by Buruli ulcer. Unfortunately the exact mechanism of transmission is not known. Even though some risk factors associated with contracting the disease have been identified in previous studies, what pertains in Suhum-Kraboa-Coaltar and Akuapem South districts of the Eastern region is not known. In addition, there is lack of detailed understanding of how environmental and social conditions interact to cause the disease. Finally, the spatial distribution of BU within the communities along the course of Densu river in the study area is also not known. Spatial epidemiology has proven to be useful for understanding the geographical distribution of many diseases. Combining the Geographical Information System (GIS) technology for epidemiologic mapping of Buruli ulcer cases alongside with environmental features and a fine detail case-control study to identify risk factors associated with Buruli ulcer will provide current knowledge of the disease in the study area. This information is crucial in developing clear interventional messages for community education on the disease and which communities are most at risk. The absence of these hampers the prevention and control of BU within the municipalities and consequently leads to ineffective use of scarce resources hence the need for the research. This study sought to develop a risk profile for the transmission of Buruli Ulcer at the individual and at the Community level in Akuapem South and Suhum Kraboa Coaltar Districts and spatial distribution of Buruli ulcer in the communities along the entire course of the Densu river. A Case-control study with Spatial mapping was carried out. The cases were identified through active community case search. A case of Buruli ulcer was defined as any person aged 2 years or more who resides in the Suhum-Kraboa-Coaltar and Akuapem South districts diagnosed of Buruli ulcer meeting the WHO clinical case definition for M. ulcerans disease. A Control was defined as any person who resides in the same community/neighbourhood as the Buruli ulcer patient comes from but does not have the disease. Standardized questionnaires were administered to the cases as well as their controls. Geographic Positioning System (GPS) receiver was used to map the cases as well as environmental characteristics that are of particular interest in contracting BU. A backward elimination logistic regression analysis of the data indicated that presence of wetland in the neighborhood (OR=3.9, 95% CI=1.9 -8.2), insect bite in water/mud (OR=5.7, 95% CI = 2.5 -13.1), use of adhesive when injured (OR=2.7, 95% CI = 1.1- 6.8), washing in the Densu river (OR= 2.3, 95% CI = 1.1- 4.96) were significantly associated with the development of BU. Rubbing an injured area with alcohol (OR=0.21, 95% CI = 0.008-0.57) and wearing long sleeves to farm (OR=0.29, 95% CI =0.14 - 0.62) protects against BU. The mapping showed that communities upstream along the Densu River where the river is not polluted had no BU cases but BU cases were identified beyond the polluted area of the Densu river. There was clustering of cases of Buruli ulcer in some communities and these occurred in areas where the river was most contaminated .Hence to avoid contamination.