A parasitic worm that is the causative agent of elephantiasis. Adults of the species live in human lymph nodes and ducts. Females give birth to sheathed microfilariae, which remain in internal organs during the day hut at night are in circulating blood, where they are sucked up by night-biting mosquitoes, in which they continue their development, becoming infective larvae in about 2 weeks. They are then passed on to humans when the mosquito bites.