Fig. 295.—Loa loa: lateral view of tail of male showing papillæ. (After Lane and Leiper.)
Fig. 296.—Loa loa. a, ventro-lateral aspect of tail showing papillæ and one spicule; b and c, terminations of the two spicules. (After Leiper.)
Site of Worms.—In various localities; under the muscular aponeuroses on extensor surfaces of arms and legs, fingers, trunk, eyelid, conjunctiva, frænum linguæ, penis, pericardium, anterior chamber of eye, and, according to some authorities, in lymphatic vessels, e.g., those of spermatic cord. As many as thirty adults may be found. The worms appear to be frequently immature, and it has been stated that worms in superficial parts are immature, those situated deeply are mature, but the data are few.
The first accounts of Loa loa—long since forgotten—were reported by Pigafetta, and are contained in a book of travels on the Congo printed in 1598. In an accompanying illustration is depicted, not only the ancient method of extraction of the Medina worm, but also the operative removal of the filaria from the conjunctiva. Subsequently the presence of the worm in negroes was confirmed by Bajon in Guiana (1768) and by Mongin in Mariborou (San Domingo), likewise in a negro (1770). At about this time a French ship’s doctor, Guyot, was cruising on the West Coast of Africa; he observed the parasite termed “loa” by the natives, and learned that it was frequent in the negroes of the Congo district. Since that time numerous observations have been reported. It was formerly common in South America, where the parasite was imported by slaves, but it disappeared when the traffic ceased; it was particularly prevalent in the Congo, where it occurs not only in natives, but also in Europeans. During recent times it has repeatedly been observed in Europe in negroes as well as in white men who have lived on the West Coast of Africa.
Nematodes of different size have been repeatedly observed in the eye of man, in the anterior chamber, lens and vitreous. For example, Mercier, in 1771 and 1774, removed a filaria out of the anterior chamber of two negroes in St. Domingo. One was 36 mm. long. Barkan, in 1876, in San Francisco, removed one from the eye of an Australian. Again, Cappez and Lacompte, in Brussels, in 1894, observed for some weeks immature Nematodes in the eye of a negro girl, aged 2 1/2 years, and then removed them. What these Nematodes actually were in these cases it is impossible to say.
Structure of Larvæ.—In dried films the larva varies in size from 140·5 µ to 166·5 µ, average, 152·5 µ; while another set of measurements gave the values 131 µ, to 150 µ, average, 143·6. In films fixed with hot alcohol the dimensions were 208 µ to 254 µ, average, 231 µ.