Tissue reaction in experimental cysticercosis of sheep and goats caused by infection with Taenia saginata eggs.

In experimental infection of sheep with Taenia saginata eggs the intensity of infection may be influenced by the age of the animal at the time of infection, the height of the infection dose and the mode of infection (perorally in capsules or by means of an oesophagus tube). In non-adequate intermediate hosts of T. saginata (sheep, goats), the cellular reaction around the young cysticercus is very strong, but it differs from the reaction known in bovine cysticercosis: large macrophages, which migrate to the larva at the early phase of infection in cattle, are lacking in sheep and goats. Neither the new formation of collagen in the granulation tissue was observed in these hosts, but the demarcation of the mode was formed by a wide zone of connective tissue at the periphery. The development of the cysticercus was markedly retarded and already four weeks after infection a majority of cysticerci were dead. Nodular changes persisted still 40 days p.i., when the cysts are transparent in cattle. Neither cysticerci nor their remnants were found at that time. The results of indirect haemagglutination reaction are not constant in inadequate intermediate hosts (particularly in sheep) and only low titres of antibodies can be detected even in strong infections.