Humans
Rain forest areas of west Africa and equatorial Sudan
Adults live in subcutaneous tissues. The microfilariae are periodic, appearing in the peripheral blood in maximal numbers during daylight hours and concentrating in the lungs at night. The intermediate host is the deer fly Chrysops. The nematodes develop to the third-stage, filariform juveniles in the fat body of the fly, after which they migrate to the mouthparts. The prepatent period in humans is about a year, and adult worms may live at least 15 years.
Adults have a tendency to wander through the subcutaneous connective tissues. When they are still, the host reaction results in localized "Calabar swellings", which disappear when the worm moves on. Adults also migrate through the conjuctiva and cornea with swelling of the orbit and psychosomatic results to the host.
Diagnosis is by demonstration of microfilariae in the blood. Surgical removal of swellings. Chemotherapy as in bancroftian filariasis. Control of deer flies is difficult.
Simple head with no lips and eight cephalic papillae; a long, slender body; and a blunt tail. The cuticle is covered with irregular, small bosses, except at the head and tail. Males are 20 to 34 mm long by 350 to 430 um wide. The three pairs of preanal and five pairs of postanal papillae are often asymmetrical. The spicules are uneven and dissimilar, 123 and 88 um long. Females are 20 to 70 mm long and about 425 um wide. The vulva is about 2.5 mm from the anterior end, and the tail is about 265 to 300 um long.