 Mansonelliasis is caused by nematodes (roundworms) in the Mansonella genus that reside in the skin or certain body cavities.The specific species are "M. perstans", "M. streptocerca" and "M. ozzardi".During a blood meal, an infected midge (genus "Culicoides") or blackfly (genus "Simulium") introduces third-stage filarial larvae onto the skin of the human host, where they penetrate into the bite wound.