Development of oncospheres of Taenia saginata after a concomitant infection by oral and subcutaneous routes.

Two experimental bulls (weight 200 kg each) were infected with activated oncospheres of Taenia saginata. The infective dose (160,000 oncospheres) was administered twice to each animal, once by oral, once by subcutaneous routes. At 6 hr p.i., a boil appeared at the site of puncture which attained a diameter of 5.5 cm and 6.2 cm respectively within 3 days, and a thickness of 1.8 cm and 2.2 cm. The postmortem disclosed an extremely weak total infestation of the muscles (approximately 30 cysticeri). The inflammatory tissue of subcutaneous foci contained eggs with an embryophore. Part of the eggs were enclosed in multinucleate giant cells. The tissue reaction differed in dependence on the viability of the oncosphere in the egg. Either giant cells were produced as in the presence of a foreign body, or there was a local accumulation of eosinophiles which after their destruction, were replaced by a crystalline conglomerate containing an egg in its centre. In addition, we found young stages of cysticerci affected by dystrophy. Remarkable eosinophile substances observed on the surface both of some eggs and of developing cysticerci (an analogy of the Splendone-Hoepli phenomenon) apparently indicated a binding of antibodies to the antigenic structure.