Loiasis

Loiasis, also known as African eye worm, is a vector-borne parasitic disease caused by the filarial nematode Loa loa and transmitted by the bite of tabanid vectors (Chrysops dimidiata) from the genus Chrysops. Loiasis exists exclusively in Africa, especially in forested areas of Central and West Africa where prevalence rarely exceeds 30% in endemic communities. The real burden of the disease is yet to be established, and L. loa remains wrongly classified as a benign disease; however, the disease has become important because of the serious adverse events which occur in some heavily infected patients after treatment with Mectizan for onchocerciasis or lymphatic filariasis. The life cycle of the parasite takes about 10 days in the vector (intermediate host) and about 3 months in humans (definite host). The passage of the adult worm in the bulbar conjunctiva is the classic manifestation of loiasis. Other manifestations are common migratory transient oedema (Calabar swellings). Both are used in the clinical diagnosis, complemented by microscopy for microfilaria. Rare but serious manifestations of Loa loa such as encephalitis, glomerular damage, retinal damage, endomyocardial fibrosis, albuminuria and hydrocele may also occur. Both surgical removal of adult worms and chemotherapy are used for managing L. loa. Currently Diethylcarbamazine (DEC), Mectizan®, mebendazole (MBZ) and albendazole (ALB) are effective in varying degrees against mf and/or adult L. loa, while further research is needed to improve the efficacy of ALB in the management of L. loa.