CHAPTER ONE

1.0 INTRODUCTION

Lymphatic filariasis, caused by parasitic Wuchereria bancrofti, is a mosquito borne disease characterized by a broad spectrum of clinical manifestation such as temporal/permanent disability and disfiguring leading to severe damage and painful swellings (lymphedema) of the legs and genitals in the late stage of the disease (Hoerauf et al., 2011; WHO, 2012; Gomase et al., 2013) and eventually stigmatization (WHO, 2013). Although the events leading to the development of chronic pathology in lymphatic filariasis are not fully understood, live filarial parasite and/or their products have a direct effect on lymphatic endothelial cells and in the cells of the innate and adaptive immune system (Nutman, 2013). Vascular endothelial growth factor (VEGF) family which is key regulators of endothelial cell functions has been implicated in lymphangiogenesis and angiogenesis in lymphatic pathology (Pfar et al., 2009). Their levels are significantly elevated in individuals with filarial infection both in chronic and microfilaremic states (Bennuru et al., 2010). The key mediators when it comes to complications associated with lymphatic filariasis are toll like receptors (TLR). They are pattern recognition factors of the innate immune system responsible for the microbial detection and initiation of the host immune response (Kawai and Akira, 2010). Wolbachia, a Gram negative endosymbiont in filarial parasites are key inducers of pro inflammatory cytokines which interact with the immune system through TLR2 thus, contributing to the pathology of lymphatic filariasis (Hise et al, 2007).