Medical Definition of Loa loa

  • Medical Author:
    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Loa loa: The eye worm, a parasite that lives in humans and other primates. People contract the parasite when bitten by infected deer flies. The larvae of the worm enter the bloodstream and later develop into adult worms. Symptoms may not appear for months or years after the bite of the fly. The worms migrate through the skin causing local inflammatory reactions called Calabar swellings. The worms can often be seen migrating across the conjunctiva and cornea of the eye. Hence, the name "eye worm." The worm sometimes enters the brain causing encephalitis. The microfilarial (tiny thread-like) form of the worm is found in blood and lymphatic fluid during the day and in the lungs at night. The insect vector (that carries the parasite) is the deer fly Chrysops which lives in swampy areas of the forest, principally in the Congo River region, Sudan, and Ethiopia. Diagnosis is by detection of the microfilariae in the blood. Protective measures against the flies include the use of a repellent, long-sleeved shirts and long pants, and the use of bednets when sleeping. Treatment is with diethylcarbamazine (DEC) or ivermectin (Stromectol). DEC can also be used for prophylaxis. The disease caused by loa loa is called loiasis or lymphatic filariasis.

Reviewed on 12/11/2018

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