Setaria equina, Abildg., 1789.
Syn.: Gordius equinus, Abildg., 1789; Filaria equi, Gmelin, 1789; Hamularia lymphatica, Treutler, 1793; Tentacularia subcompressa, Zedder, 1800; Filaria papillosa, Rud., 1802; Filaria hominis bronchialis, Rud., 1819; Filaria hominis, Dies., 1851; Strongylus bronchialis, Cobb., 1879.
The body is whitish, filiform, pointed posteriorly. The cuticle presents a delicate transverse striation. The mouth is small, round, and surrounded by a chitinous ring, the border of which carries, at the sides, two semilunar lips, and there is on the dorsal as well as on the ventral surface a papilliform process; on the tail, corresponding with each sub-median line, is a conical papilla. The male measures 6 to 8 cm. in length; the posterior extremity ends in a corkscrew spiral; there are on each side four pairs of pre-anal and four or five post-anal papillæ; the spicules are unequal. The female measures 9 to 12 cm. in length and is viviparous; the embryos measure 0·28 mm. in length and 0·007 mm. in breadth.
Fig. 289.—Setaria equina: anterior end, magnified. (After Railliet.)
Setaria equina is a frequent parasite of horses and asses; it inhabits the peritoneal cavity, and from there occasionally invades the female genitalia or even the liver; it is found more rarely in the pleural cavity or in the cranium. The statement that it also occurs in the subcutaneous connective tissue is probably due to confusion with Setaria (Filaria) hæmorrhagica, Raill., 1885 (Filaria multipapillosa, Cond. et Drouilly, 1878). Setaria labiata papillosa (immature form) occurs in the eye of the horse, adults in the peritoneal cavity.
Treutler, in 1790, found a filaria in the enlarged bronchial lymphatic gland of a patient suffering from phthisis. It measured 26 mm. in length and had two spicules, which Treutler mistook for mouth hooks, hence the name Hamularia. Blanchard mentions another case from Geneva, Brera a third and v. Linstow a fourth. As shown by the synonyms, a few authors consider this form to be a distinct species, which is hardly probable.
Genus. Loa, Stiles, 1905.
Characterized by the possession of cuticular bosses in both sexes (fig. [294]).