Insights into the pathogenesis of disease in human lymphatic filariasis

Abstract

Although two thirds of the 120 million people infected with lymph-dwelling filarial parasites have subclinical infections, ∼40 million have lymphedema and/or other pathologic manifestations including hydroceles (and other forms of urogenital disease), episodic adenolymphangitis, lymphedema, and (in its most severe form) elephantiasis. Adult filarial worms reside in the lymphatics and lymph nodes and induce lymphatic dilatation. Progressive lymphatic damage and pathology results primarily from the host inflammatory response to the parasites but also perhaps from the host inflammatory response to the parasite's Wolbachia endosymbiont and as a consequence of superimposed bacterial or fungal infections. This review will attempt to shed light on disease pathogenesis in lymphatic filariasis.

FIG. 1.

Pathogenesis of lymphatic filarial disease (lymphedema, hydrocele, elephantiasis). Live filarial parasites and/or their products have a direct effect on lymphatic endothelial cells and on the cells of the innate and adaptive immune system. The interplay among inflammatory/ immune mediators, attrition of the parasites, Wolbachia and other factors contribute to pathogenesis and development of filarial disease. Secondary microbial infections further aggravate the pathology. A color version of this figure is available in the online article at www.liebertpub.com/lrb