March 30 - Loa loa

Loa loa, also known as the “eye worm,” gets its name from an affinity for subcutaneous tissue like the tissue found in human eyes. This nematode parasite finds its way into humans through the deer fly, in which the Loa loa worm larvae develop. Once in its third stage, a larva can enter a human when a deer fly bites. When larvae mature within subcutaneous tissue, they produce microfilariae – an uninfective stage of the Loa loa, which are then picked up by other deer flies. These parasites can be removed surgically, but drugs are required to kill microfilaria within the bloodstream. Adults can survive in subcutaneous tissue for up to 17 years, and take one year to fully mature. The first recorded case of Loa loa dates back to the year 1770 when a surgeon failed to remove a worm in a woman’s eye in the Caribbean. Loa loa was again found in slave ships coming to America. Loa loa has not been diagnosed in the United States in almost a century, but the parasite is still endemic to western and central Africa. While not fatal, Loa loa can be a complication for patients with other diseases. These microscopic worms are hard to see, unless they’re in your eye.


References:
1. Loa loa: A cutaneous filarial parasite of humans. Filarial Biology.
2. Muller, R. Worms and Human Disease. New York: CABI, 2002.

Contributed by Prath Devre, Bucknell University.