Loiasis

Abstract

Loa loa is a long-lived parasite (up to 20 years of age) which is transmitted through the bites of deer flies (mainly Chrysops dimidiata and C. silacea). L. loa is endemic to Africa, from southeastern Benin in the west to southern Sudan in the east, and down south to Angola and possibly Zambia. Loiasis was first identified during the slave trade period. At that time, the disease was depicted by the spectacular passage of the adult worm under the bulbar conjunctiva of the eye (“eye worm”) and the transient episodes of subcutaneous migratory edema referred to as “Calabar swelling.” Since then, loiasis has also been associated with more severe symptoms such as cardiopathy (involving hypereosinophilia), nephropathy, and hormonal disturbance. Despite its endemic presence in Central Africa, with possibly tens of millions individuals concerned by the disease, loiasis has drawn little attention until the implementation of mass drug administration for lymphatic filariasis and onchocerciasis in the region. Indeed, post-therapeutic serious adverse events (SAEs) have occurred in individuals harboring high density of L. loa microfilariae. Solutions to prevent those SAEs are currently under evaluation in the field, but specific operational research on loiasis should nonetheless be encouraged.

Due to the intimate relationship among lymphatic filariasis, onchocercosis, mansonelliasis, and loiasis on diagnosis, distribution, and treatment, all four chapters need to be checked when solving problems related to any of them (CBM).