Loiasis

The disease caused by the eye worm known as loa loa, 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. Loiasis is also known as lymphatic filariasis.

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A chronic disease caused by the filarial nematode Loa loa, with symptoms and signs first occurring approximately 3–4 years after a bite by an infected tabanid fly. When the infective larvae mature, the adult worms move about in an irregular course through the connective tissue of the body (as rapidly as 1 cm per minute), frequently becoming visible beneath the skin and mucous membranes; e.g., in the back, scalp, chest, inner surface of the lip, and especially on the conjunctiva. The worms provoke hyperemia and exudation of fluid, often a host response to the worm products, a Calabar or fugitive swelling which causes no serious damage and subsides as the parasites move on; the patient is annoyed by the “creeping” in the tissues and intense itching, as well as occasional pain, especially when the swelling is in the region of tendons and joints. Most patients have an eosinophilia of 10–30 or 40% in the circulating blood. SYN: Calabar swelling, fugitive swelling.

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loiasis var of LOAIASIS

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n.

a disease, occurring in West and Central Africa, caused by the eye worm Loa. The adult worms live and migrate within the skin tissues, causing the appearance of transitory calabar swellings. These are probably an allergic reaction to the worms' waste products, and they sometimes lead to fever and itching. Worms often migrate across the eyeball just beneath the conjunctiva, where they cause irritation and congestion. Loiasis is treated with diethylcarbamazine, which kills both the adults and larval forms.

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lo·i·a·sis (lo-iґə-sis) infection with the nematode eye worm Loa Loa, which inhabits subcutaneous connective tissue, especially around the orbit and under the conjunctiva, causing itching, eosinophilia, and occasionally edematous swellings called Calabar swellings. In rare severe cases, worms may migrate farther into the body and cause inflammation of joints or internal organs. Called also loaiasis.