Written by Ada’s Medical Knowledge Team
What is Loiasis?
Loiasis is an infection that affects the skin or the eyes. It's also called African eye worm. The infection is caused by Loa loa worms. These worms are spread to humans by the bite of a deerfly, which is also known as a mango or mangrove fly. The infectious flies are most common in West and Central Africa. The risk of infection is higher in rainforest areas, especially during the rainy season. There may be a delay of weeks to years before symptoms appear. Many people with the infection will not experience any symptoms at first. When symptoms do occur, they most commonly involve itchy swellings under the skin. They usually change position or disappear within days or weeks. These swellings are a reaction to the Loa loa worm under the skin. The worms may also move to the eye, causing irritation. An outline of the worm may be visible below the surface of the eyeball. Diagnosis is based on the affected person's history and a physical exam. A blood test or removal of a worm from the skin or eye can confirm the diagnosis. The infection is treated with antiparasitic medication, and most people recover well. Those with a serious infection are at risk of complications affecting the brain, heart, or kidneys.