The inflammatory reaction surrounding Taenia solium larvae in pig muscle: ultrastructural and light microscopic observations.

An inflammatory reaction with the general characteristics of a chronic granuloma surrounding Taenia solium larvae in pig muscle is described. Larvae with an inflammatory capsule were obtained at slaughter from pigs 6-8 months-of-age and were processed for light and electron microscopy. Eosinophils (granulocytes with orange staining and peroxidase-positive granules) were found to be degranulated and in close contact with the parasite surface. Histiocyte, epithelioid cells, macrophages and lymphocytes were also evident, as well as large numbers of plasma cells in the outer areas of the wall-circumscribed reaction. The parasites were ultrastructurally intact, with a normal tegument and only occasional changes in the microvesicles. The results are discussed with reference to parasite survival in the host.