The role of Wolbachia bacteria in the pathogenesis of onchocerciasis and prospects for control of the disease.

Onchocerciasis, a non-fatal disease, is a major public health problem especially in sub-Saharan Africa causing disfigurement, severe itching, skin depigmentation, vision impairment and eventually blindness. The discovery of Wolbachia intracellular bacteria in the filarial nematodes has contributed a lot to the understanding of host's immune response to the bacteria and its role in the pathogenesis of onchocericiasis. Lipopolysaccharide molecules (LPS) associated with the bacteria are responsible for the induction of potent inflammatory responses mainly mediated by macrophages. LPS binding to CD14 on the monocytes/macrophages which is a co-receptor for Toll like receptor (TLR), induces the activation of an intracellular signaling that leads to the production of proinflammatory cytokines such as TNF-alpha, IL-1, IL-12 by macrophages. The cytokines initiate the recruitment of neturophils and macrophages to the vicinity of the adult worms/microfilaria especially to the cornea, which gradually causes corneal pathology. Therefore studies have suggested that Wolbachia plays an essential role in the induction of inflammatory response associated with the pathogenesis of onchocericiasis through the activation of innate immune response. Hence the aim of this study is to show the role wolbachia plays in the pathogenesis of this devastating illness and target for novel chemotherapy.