Also Known As: Loiasis, African eye worm, Fugative swelling, Tropical swelling, Loa loa filariasis, Loa loa
Loa loa filariasis (also known as loiasis, loaiasis, Calabar swellings, Fugitive swelling, Tropical swelling and African eyeworm) is a skin and eye disease caused by the nematode worm, loa loa. Humans contract this disease through the bite of a Deer fly or Mango fly (Chrysops spp), the vectors for Loa loa. The adult Loa loa filarial worm migrates throughout the subcutaneous tissues of humans, occasionally crossing into subconjunctival tissues where it can be easily observed. Loa loa does not normally affect one's vision but can be painful when moving about the eyeball or across the bridge of the nose. The disease can cause red itchy swellings below the skin called "Calabar swellings". The disease is treated with the drug diethylcarbamazine (DEC), and when appropriate, surgical methods may be employed to remove adult worms from the conjunctiva.
Human loiasis geographical distribution is restricted to the rain forest and swamp forest areas of West Africa, being especially common in Cameroon and on the OgoouÃ© River. Humans are the only known natural reservoir. It is estimated that 12-13 million humans are infected with the Loa loa larvae.
An area of tremendous concern regarding loiasis is its co-endemicity with onchocerciasis in certain areas of west and central Africa, as mass ivermectin treatment of onchocerciasis can lead to serious adverse events (SAEs) in patients who have high Loa loa microfilarial densities, or loads. This fact necessitates the development of more specific diagnostics tests for Loa loa so that areas and individuals at a higher risk for neurologic consequences can be identified prior to microfilaricidal treatment. Additionally, the treatment of choice for loiasis, diethylcarbamazine, can lead to serious complications in and of itself when administered in standard doses to patients with high Loa loa microfilarial loads.