Encephalitis Due to Loa loa

Abstract

Loa loa encephalitis is becoming an important public health problem, as it impedes the use of some important drugs (ivermectin and DEC) for mass control of filarial disease in parts of West Africa where onchocerciasis is endemic. Loa encephalitis may occur either spontaneously or following chemotherapy targeting Loa loa. Although Loa loa is restricted to the West African rain forest block, imported cases are described throughout the world, due to intense economic, cultural and touristic population exchanges. The most common clinical features of loiaisis are swelling angioedema (calabar oedema) and ocular passage of the adult worm under the conjunctiva (eye worm). Loa loa disease may be particularly severe in expatriates (Nutman et al., 1986). Loa loa may cause a localized or systemic disease with involvement of deep organs including the kidney and heart. Only one-third of infected individuals have microfilariae in peripheral blood, leading to an underestimation of the prevalence of this infection. Most expatriates with loiasis have the adult worm but are amicrofilaremic (Churchill et al., 1996). The heterogeneous clinical expression of loisais encephalopathy calls for greater awareness among scientist and medical practitioners worldwide.