The term used to describe several clinical entities caused by one or other of the nematode ﬁlariae; these include Wuchereria bancrofti/Brugia malayi, Onchocerca volvulus, Loa loa, Dracunculus medinensis (DRACONTIASIS or guinea-worm disease), Mansonella perstans, etc. These organisms have widely diﬀering geographical distributions. Whereas lymphatic ﬁlariasis is present throughout much of the tropics and subtropics, ONCHOCERCIASIS (river-blindness) is largely conﬁned to west and central Africa and southern America. Loaiasis is an infection of west and central Africa, and dracontiasis involves west and central Africa and western India only.
Clinically, the lymphatic ﬁlariases characteristically cause ELEPHANTIASIS (lymphoedema); onchocerciasis gives rise to ophthalmic complications (river-blindness), rashes and subcutaneous nodules; loaiasis causes subcutaneous ‘Calabar swellings’ and subconjunctival involvement; and dracontiasis predisposes to secondary bacterial infections (usually involving the lower limbs). Diagnosis is by ﬁnding the relevant ﬁlarial nematode, either in blood (day and night ﬁlms should be examined), or in one or other of the body ﬂuids. An EOSINOPHILIA is often present in peripheral blood. Serological diagnosis is also of value. In onchocerciasis, skin-snips and the Mazotti reaction are valuable adjuncts to diagnosis.
The mainstay of chemotherapy consists of diethylcarbamazine (aimed predominantly at the larval stage of the parasite). However, ivermectin (not available in the UK) is eﬀective in onchocerciasis, and metronidazole or one of the benzimidazole compounds have limited value in dracontiasis. Suramin has been used to kill adult ﬁlarial worms. Prevention consists of eradication of the relevant insect vector.