This parasite is quite common, but comparatively harmless. Its habitat is the caecum and the neighboring section of the intestine. It lives upon blood which it abstracts from the intestinal mucosa. This parasite is 4-5 cm. long, the male being smaller than the female. The head end, which is about three-fifths of the entire length, is drawn out into a fine thread; the tail end is not so thin, being up to 1 mm. in thickness (Fig. 64). The male has a spiral body from the end of which the spicule projects. The body of the female is straight and terminates in a blunt extremity. The ova are almost lemon-shaped, dark brown in color, 0.05 mm. in diameter (Fig. 65). The number of eggs in a single female was estimated by Leuckart at 58,000. They are hatched out very slowly.

Trichocephalus Dispar.

Fig. 64. - Trichocephalus Dispar. (Heller.) a, Female. b, male. Natural size.

Ova of Trichocephalus Dispar in Process of Development.

Fig. 65. - Ova of Trichocephalus Dispar in Process of Development. (Huber.)

Leuckart asserts that the dispersion of the eggs and consequent spread of infection may readily occur through wind, rain, or dust, and that the eggs may be ingested with fruit and salads. The number of these worms found in one patient is usually small, from six to twenty.

The symptoms are but very slight, occasionally diarrhoea exists, sometimes there are some reflex nervous conditions.

The diagnosis can usually be easily made from the shape of the ova. The passage of the living worms in the stools occurs but rarely.

With regard to treatment Lute; recommends the administration of thymol; Mosler 1 and Peiper2 employ rectal irrigation of water, to which a few drops of benzene have been added. Extract of male-fern may also be used internally.