Inoculation of calves and adult cattle with oncospheres of Taenia saginata and their resistance to challenge infection.

Following intramuscular inoculation of Taenia saginata eggs hatched in vitro, 1-month-old calves were capable of developing a complete immunity to the establishment of a living infection by oral challenge. Cysticerci developed at the injection sites and produced an effective immunity whether the hatched oncospheres were activated in vitro or not. A few living cysticerci found at sites other than the inoculation sites were derived from the inoculation dose and parasite migration from the inoculation sites was also observed in control calves which had not been orally challenged. Such migration was much less frequent in adult cattle. Adult cattle which had been orally infected many times were resistant to infection by intramuscular inoculation. Disseminated infections developed in young calves infected by the intravenous and intraperitoneal routes with hatched eggs. The ELISA test was found to be more sensitive at detecting serological antibodies in infected calves than the IHA test.