In South America, Ac. perstans is very common amongst the aboriginal Indians in the interior of British Guiana. However, it is not found in Georgetown and in New Amsterdam, neither is it found in the cultivated strip of coast lying between these two towns, but it is common on the coast farther north near the Venezuelan boundary, where the forests stretch to the sea. The Waran Indians, who live at the mouth of the Waini river, harbour this parasite. It is absent in the West Indies.
Topographically, Ac. perstans is found only in areas covered by dense forest growth and abounding in swamps. In Kavirondo, where the forest disappears and the land is covered with scrub and short grass, it is not found; likewise it is not found on the grassy plains of the highlands of British East Africa. Towns and cultivated areas are free from it.
Genus. Dirofilaria. Railliet and Henry, 1911.
Body very long, thread-like, cuticle transversely striated. Mouth with six papillæ. Male tail spiral with voluminous pre-anal and some large post-anal papillæ; spicules unequal. Vulva near the anterior hundredth of body; viviparous. Parasitic in heart or blood-vessels and subcutaneous tissue.
Dirofilaria magalhãesi, R. Blanchard, 1895.
Syn.: Filaria bancrofti, v. Linstow, 1892; Filaria bancrofti, P. S. de Magalhães, 1892 (nec Cobbold, 1877).
Fig. 300.—Dirofilaria magalhãesi: posterior extremity. (After v. Linstow.)