Zoological distribution.— Hitherto L. loa has not been seen by reliable observers in animals, but, according to Plehn, the natives of Cameroons assert that it occurs in goats and sheep.
The parasite (Figs. 154, 155). L. loa is especially characterized among the nematodes of man by the presence of numerous rounded, smooth, translucent protuberances of the cuticle, 12-16 μ in diameter and rising 9-11 μ above the general surface. These chitinous bosses vary greatly in number and arrangement on different specimens and are, as a rule, more numerous on the female. Their distribution is very irregular. In the male they are wanting at the extremities, beginning about 1.5-2.5 mm. from the mouth and tail- tip respectively. In the female they usually extend to the posterior extremity and may also be found on the cephalic end.
The body is filiform, cylindrical, whitish, semi-transparent. Anteriorly it tapers somewhat abruptly to the mouth, which is terminal, small, simple, unarmed, and apparently destitute of papillæ. There is no distinctly marked neck, but there is a sort of shoulder about 0.15 mm. from the mouth, and at about this level are two small papillæ, one corresponding to the dorsal, the other to the ventral median line.
The posterior extremity of the female is straight, attenuated, and broadly rounded off (Fig. 156). That of the male is slightly curved ventrally and provided with two lateral expansions of the cuticle (0.7 mm. long by 0.029 mm. broad), situated nearer the ventral than the dorsal surface. In the middle of the ventral surface, between the lateral alæ, and about 0.080 mm. from the tail-tip, is the opening of the ano-genital orifice, from which two unequal spicules may be seen protruding. The opening is surrounded by thick labia. On either side, and somewhat asymmetrically placed, are four large globular and pedunculated papillæ closely approximated and decreasing in size antero-posteriorly. Farther back, and nearer to the middle line, is a fifth symmetrical pair of very small, conical, postanal papillæ with broad base and acuminated point. (Fig. 157.) Leiper has reported the existence of three additional paired papillæ.
The adult male worm measures 30-34 mm. in length, and presents a maximum breadth of 0.350-0.430 mm. in the anterior part of the body. The posterior part tapers gradually towards the tail. The measurements of the adult female have not been satisfactorily determined. The specimens so far examined, extracted from under the skin or from about the eyes of patients, varied greatly in length*[1] 20 mm. (Blanchard); 27 mm. (Leuckart); 32.3 mm. (Manson); 50 mm. (Annett, Dutton and Elliot); 52 mm. (Looss); 55 mm. (Ozzard); 60 mm. (Brumpt); 70 mm. (Maurel).
- ↑ * If the record of Guy on (1864) that his specimen was 15 cm. long does not rest on an error in transcribing or printing, it shows that the fully grown female is really much larger than we know at present from the extracted subcutaneous specimens.
