Page:Tropical Diseases.djvu/903

XLV] The parasite(Fig. 193) is the largest trematode inhabiting man. It measures 24 to 40 mm. or more (75 mm. according to Busk) in length by 12 to 14 mm. in breadth. In shape it is an elongated oval, rather narrower anteriorly than posteriorly, with flat ventral surface, slightly convex dorsal surface, and very thin margins. It has a smooth skin without spines. The oral sucker (0·5 mm. in diameter) is subterminal and placed on the ventral surface. The ventral sucker is larger (1·6 to 2 mm. in diameter) and placed close to the oral. It is prolonged into a kind of sac (2-8 mm. long) directly under the ventral surface. The pharynx (0·7 mm. long) is preceded by a prepharynx (0·28 mm. long); the œsophagus is very short and the intestinal cæca are simple and present two characteristic curves towards the middle line, one at about the middle of the body, the other between the testes. The genital pore opens on the median line immediately anterior to the ventral sucker. The testes are in the posterior half of the body, one behind the other; both are branched dichotomously. The ovary is branched, and is placed about the middle of the body on the right of the median line. The vitellaria are well developed, and extend from the ventral sucker to the caudal end of the body, where they meet. The acini are very small. The eggs (Figs. 169, g, and 194) are numerous and measure 120 to 130 μ in length by 77 to 80 μ in breadth; they are closed, I find, by a very delicate operculum.

Pathogenesis and treatment.—This parasite inhabits the upper part of the small intestine. In two recorded instances (Cobbold) it was associated with attacks of recurring diarrhœa and other signs of intestinal irritation. The best treatment is thymol or eucalyptus oil, given as in ankylostomiasis.

Under the name of F. rathouisi a fluke was described by Poirier in 1887. The validity of this species has given rise to a good deal of discussion. Odhner, who has examined the type specimen, believes the so-called distinctive features are solely due to error in the interpretation of serial sections of F. buski. `