Loiasis: African eye worm

The filarial parasite Loa loa is transmitted by Chrysops fly bites. Loiasis is endemic in rainforest areas of West and Central Africa, and sporadic cases have also been diagnosed in travellers and migrants. Whilst many infected persons are asymptomatic, microfilariae may be detected in the blood or adult worms may be seen under the skin or the sclera of the eye. Mass treatment programmes for onchocerciasis have raised concern about the risk of severe adverse effects when ivermectin is distributed in areas co-endemic for onchocerciasis and loiasis.