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[Brugia malayi] [Brugia timori] [Dirofilaria spp.] [Loa loa] [Mansonella ozzardi] [Mansonella perstans] [Mansonella streptocerca] [Onchocerca volvulus] [Wuchereria bancrofti]

During a blood meal, an infected black fly (genus Simulium) introduces third-stage filarial larvae of Dirofilaria ursi onto the skin of the ursine definitive host (although humans may also serve as hosts), where they penetrate into the bite wound .  In subcutaneous tissues, the larvae develop into adults, which commonly reside in subcutaneous connective tissues .  Adult females are usually 115-225 mm long by 460-700 µm wide; males are usually 50-90 mm long by 330-480 µm wide.  Adults can live for 5 - 10 years.  In the subcutaneous tissues, the female worms are capable of producing microfilariae over their lifespan.  The microfilariae are found in peripheral blood .  A black fly ingests the microfilariae during a blood meal .  After ingestion, the microfilariae migrate from the black fly's midgut through the hemocoel to the Malpighian tubules in the abdomen .  There the microfilariae develop into first-stage larvae and subsequently into third-stage infective larvae .  The third-stage infective larvae migrate to the black fly's proboscis and can infect another definitive host when the fly takes a blood meal .  Humans are not common hosts, but may become so after being fed upon by infected black flies .