Lymphatic filariasis

Abstract

Lymphatic filariasis (LF), frequently called elephantiasis, is a debilitating disease with serious social and economic impact. The infection is caused by worms of the species Wuchereria bancrofti, Brugia malayi, and B. timori. Parasites are transmitted by infected blood-feeding mosquitoes of different species of Culex, Aedes, Anopheles, and Mansonia. LF is endemic in 73 countries in Asia, Africa, and the Americas, with an estimated 120 million people affected, being 108 million of them infected with Wuchereria bancrofti and 12 million with Brugia malayi or B. timori. Filariasis is characterized by a broad spectrum of clinical disease, ranging from asymptomatic microfilaremic to acute and chronic lymphatic manifestations. In symptomatic patients the most common manifestations are hydrocele, lymphedema, and elephantiasis. The female worm produces microfilariae found in the bloodstream exhibiting a circadian rhythm (diurnal or nocturnal periodicity). Diagnosis can be performed by parasitological methods based on the detection of microfilariae by microscopic examination. Blood sample should be taken depending on parasite periodicity, when microfilariae concentration in the blood is higher. Serological techniques based on antigen detection or DNA amplification by polymerase chain reaction (PCR) can also be used. Diethylcarbamazine citrate (DEC) is considered the standard drug for filariasis therapy. However, chronic patients may not benefit from antifilarial drug requiring specific care to restore function of the affected area. Elimination programs strategies are mainly based on annual mass drug administration, environmental sanitation, vector control, treatment of infected individuals, and morbidity management to alleviate the physical disability and psychological suffering of chronically affected patients.