[2][page needed] It mainly inhabits rain forests in West Africa and has native origins in Ethiopia.

The L. loa adult worm which travels under the skin can survive up to 10–15 years, causing inflammations known as Calabar swellings.

The adult worm travels under the skin, where the female deposits the microfilariae which can develop in the host’s blood within 5 to 6 months and can survive up to 17 years.

After bites from these infected flies, the microfilariae are unique in that they travel in the peripheral blood during the day and migrate into the lungs at night.

[6] L. loa worms have a simple structure consisting of a head (which lacks lips), a body, and a blunt tail.

The outer body of the worm is composed of a cuticle with three main layers made up of collagen and other compounds which aid in protecting the nematodes while they are inside the digestive system of their host.

[2] The human is the definitive host, in which the parasitic worms attain sexual maturity, mate, and produce microfilariae.

[9] Usually, about five months are needed for larvae (transferred from a fly) to mature into adult worms, which they can only do inside the human body.

The most common display of infection is the localized allergic inflammations called Calabar or Cameroon swellings that signify the migration of the adult worm in the tissues away from the injection site by the vector.

[11] These parasites have a diurnal periodicity in which they circulate in the peripheral blood during the daytime, but migrate to vascular parts of the lungs during the night, where they are considered non circulatory.

[10] Other tissues in which this worm can be found includes: the penis, testes, nipples, bridge of the nose, kidneys, and heart.

Men are more susceptible than women due to their increased exposure to the vectors during activities such as farming, hunting, and fishing.

[13] Ivermectin has become the most common antiparasitic agent used worldwide, but can lead to residual microfilarial load when given in the management of loiasis.

Symptoms may be resolved with as little as 1–2 courses of DEC. DEC is chosen over Ivermectin because evidence supports its ability to kill both the adult worms and the microfilariae, which are the main cause of the severe neurological problems mentioned above.

The body's response to albendazole is slow, so the patient being treated must be monitored closely and frequently to ensure it is effective.

Fly bites can be reduced by using insect repellents such as DEET and wearing long sleeves and pants during the daytime.

[10] Reports of microfilaremia have been made in Angola, Benin, Cameroon, Central African Republic, Congo, the Democratic Republic of Congo, Equatorial Guinea, Gabon, Nigeria, and Sudan, and possibly rare cases in Chad, Ghana, Guinea, Liberia, Uganda, and Zambia.

The researchers concluded that L. loa would end up migrating to Europe and the United States, due to increased travel to already endemic regions.