Human Filariasis

Abstract

Human filarial infections belong to the neglected tropical diseases that occur in subtropical and tropical countries throughout the world. Filarial infections are caused by thread-like parasitic worms that are transmitted by blood-feeding insect vectors. Several human-pathogenic filarial species cause infections varying from asymptomatic cases to debilitating diseases with severe pathology. Overall, several hundred million people are infected with filarial nematodes and more than one billion people live in areas at risk of infection. Onchocerca volvulus is the causative agent of river blindness (onchocerciasis), which can lead to permanent vision loss and severe dermatitis. Wuchereria bancrofti, Brugia malayi and Brugia timori cause lymphatic filariasis, which can be accompanied by lymphedema in the extremities (elephantiasis) and hydrocele in the scrotum of men. Loa loa is the African eye worm, where adult filariae can migrate through the eye. Finally, Mansonella perstans, Mansonella sp. “DEUX”, Mansonella streptocerca and Mansonella ozzardi are the cause of mansonellosis that is probably the most neglected filarial disease due to the absence of clinical symptoms. In this chapter we provide an overview of those filariae with regard to their biology, epidemiology, pathology and immunology. Furthermore, we highlight the current diagnostic procedures, interventions and the current treatment options.