The term used to describe several conditions caused by one or other of the nematode filariae (worms); these include Wuchereria bancrofti, Brugia malayi, Onchocerca volvulus, Loa loa, Dracunculus medinensis (DRACONTIASIS or guinea-worm disease), Mansonella perstans, etc.

Clinically, the lymphatic filariases characteristically cause ELEPHANTIASIS (lymphoedema); onchocerciasis causes 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 worm, either in blood or in one of the other body fluids. EOSINOPHILIA is often found on blood testing.

Various types of FILARICIDE are used: the most commonly prescribed agent is 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 has some value in dracontiasis. Suramin has been used to kill adult filarial worms. Prevention consists of eradication of the relevant insect vector.