What is loiasis?

Loiasis, an infection endemic in the jungles of west and central Africa, is produced by the adult form of the tissue nematode, Loa loa, which is transmitted through the bite of various flies including deer flies (Chrysops species). Usually asymptomatic, this filarial disease may cause large areas of transient edema (Calabar swelling) as the worm migrates, and it may even migrate visibly across the conjunctiva. Subcutaneous nodules may also be seen in this disease, but the worm’s unique migration habits lead to the common name “eyeworm.”