**Abstract**

Filarial nematodes are parasitic worms transmitted by blood-feeding insects. Mainly found in tropical and subtropical areas of the developing world, diseases such as lymphatic filariasis and onchocerciasis represent major public health issues. With millions of people infected and billions at risk of infection, these diseases can stun economic growth and impair the life quality, hence the WHO classified both lymphatic filariasis and onchocerciasis as Neglected Tropical Diseases. The lesser known filarial disease loiasis is not only affecting millions of people, but represents a huge obstacle during mass drug administration programmes targeting other filarial diseases. Even less is known about mansonellosis, potentially the most widespread of the human filariases, but underestimated due to the lack of clinical symptoms. Large scale intervention as well as mass drug administration programmes are undertaken with the long term goal of eliminating the filarial diseases lymphatic filariasis and onchocerciasis. However, there is still neither a vaccination nor short term macrofilaricidal treatments available. The following chapter will encompass the different filarial diseases, the biology of the parasite and their vector, the epidemiology as well as pathology of the filariases, highlighting the impact of these diseases is still immense and further research in understanding and combating these diseases is needed.

**Keywords:** *Brugia*, filariasis, ivermectin, *Loa loa*, loiasis, lymphatic filariasis, *Mansonella*, mansonellosis, neglected tropical diseases, *Onchocerca volvulus*, onchocerciasis, parasitic diseases, *Wolbachia*, *Wuchereria bancrofti*
