vector-borne zoonotic diseases, spread by mosquitoes, Culex, Aedes, humans, carnivores. Filariasis is a parasitic disease caused by an infection with Filarioidea roundworms. These are spread by blood-feeding black flies and mosquitoes. Eight known filarial nematodes use humans as their definitive hosts. These are divided into three groups according to the niche they occupy in the body: Lymphatic filariasis is caused by the worms Wuchereria bancrofti, Brugia malayi, and Brugia timori. These worms occupy the lymphatic system, including the lymph nodes; in chronic cases, these worms lead to the syndrome of elephantiasis. Subcutaneous filariasis is caused by Loa (the eye worm), Mansonella streptocerca, and Onchocerca volvulus. These worms occupy the subcutaneous layer of the skin, in the fat layer. L. loa causes Loa filariasis, while O. volvulus causes river blindness. Serous cavity filariasis is caused by the worms Mansonella perstans and Mansonella ozzardi, which occupy the serous cavity of the abdomen. Dirofilaria immitis, or the dog heartworm can be found in dogs and rarely infects humans. Dirofilaria repens can be found in dogs and humans.