Apr 6, 2014
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FILARIASIS

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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.

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Medical Dictionary

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