Eye-worm, Loa loa

The eye-worm (Loa loa) is a species of roundworm within the Nematoda phylum. It can be found in India and Africa, among other areas. This species causes a disease known as Loa loa filariasis and is one of three species that can cause subcutaneous filariasis in humans. Females are larger than males, reaching an average body length of up to 2.7 inches, with males reaching an average body length of up to 1.3 inches.

The first stage of life for the eye-worm begins when an adult worm, which is present within the eye or other area of its definitive host, lays its eggs. Biting flies within the genus Chrysops will then consume the microfilariae that develop from the eggs. The microfilariae move into the fat of the fly, which is the intermediate host, and develop from first stage larvae to third stage larvae. At this point, the larvae are able to infective a definitive host, moving through the proboscis of the fly into the skin of the host. From this stage, the larvae mature into adult worms and reproduce. The eggs of this species have been found in the urine, blood, lungs, and spinal fluid of a host.

Some common symptoms of an eye-worm infection include inflammation of the skin in the area that the larvae entered and where it moves around, as well itching, fatigue, joint pain, and even death. It is relatively easy to diagnose an infection of this species by performing a blood test, which reveals the presence of microfilariae eggs, or by looking for signs of skin swelling or worms within the area of the eye. Although surgery can be used to remove this parasite, treatments that are more common include medicines like Ivermectin and diethylcarbamazine (DEC).

Image Caption: “Microfilaria of L. loa in a thin blood smear, stained with Giemsa.” Credit: CDC – DPDx/Wikipedia