Floristic Diversity as an Indicator in Low and High Endemic Buruli Ulcer Areas in Côte d’Ivoire

Abstract

Mycobacterium ulcerans is an environmental bacterium responsible for Buruli ulcer. This disease has a high frequency index in humid tropical regions, with a high incidence in Sub-Saharan Africa. The ecology and mode of transmission of this disease is not well established. Based on dilution effect hypothesis, acting as lowering disease transmission due to greater biodiversity, floristic inventory was carried out in the Health Districts of Daloa and Bouaké in Côte d’Ivoire. In each district, high and low endemic sites were investigated. A total of 169 plant species were inventoried for both low and high endemicity of Buruli ulcer sites in the districts. The Indval index revealed that 13 plant species were good indicators for Buruli ulcer highly endemic areas. The plants which correlate with high endemicity area were Leersia hexandra, Panicum laxum, Mimosa pudica, Paspalum distichum, Persicaria senegalensis, Calopogonium mucunoides, Echinochloa colona, Ipomoea sagittata, and Eichhornia crassipes. For low endemic sites, a strong relationship was recorded for 37 plants. The indices revealed low similarity between high and low endemicity sites. Low endemicity sites expressed the highest plant species diversity. These results suggest the hypothesis that floristic richness is more important in sites of low endemicity than in those of high endemicity. Moreover, we observed a co-occurrence of some plant species and Buruli ulcer endemicity. This finding may lead to the fact that it is important to care about the biodiversity to prevent outbreak of Buruli ulcer cases.