Wuchereria bancrofti (elephantiasis),
Onchocerca volvulus (river blindness),
Dirofilaria immitis (dog heartworm).
Animal parasites of the order Spirurida exhibit strong organotropism; that is, they tend to leave the digestive tract to invade the tissues. The tissue dwelling parasites are thought to be more primitive than those living in the intestine (Chabaud and Bain, 1994).
The term ‘filarial worms’or ‘filariae’ historically denotes the genera of nematodes in the family Filariidae (Cobbold 1864) Claus 1885. This was correct until the family Onchocercidae Chabaud and Anderson 1959 was established. Most of the genera that were previously considered as filarial worms of the Filariidae were transferred to the new family Onchocercidae (including Onchocerca, Loa, Brugia, Wuchereria, Dirofilaria, Acanthocheilonema, Cercopithifilaria, Deraiophoronema, Dipetalonema, Elaeophora, Litomosoides, Mansonella and Skrjabinofilaria). Only a few genera remained in the family Filariidae (Filaria, Parafilaria, Suifilaria and Stephanofilaria).
Thus, the use of 'filarial worms' or 'filariae' for denoting onchocercids, and other nematode species of public health significance became etymologically incorrect. Both Filariidae and Onchocercidae belong to the superfamily Filarioidea. While Onchocerca spp. are etymylogically not ‘filariid worms’ they are undoubtedly biologically filarioid worms. Therefore, the use the terms 'filarioid worms' or 'filarioids' as general terms for Filariidae, Onchcercidae and other taxa of similar biology, is recommended (Kassal, 2002.)
Chabaud, A., and Bain, O. 1994.
Kassal, T. 2002. A worm by any other name. Trends in Parasitology 18:246.
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