Biological and immunological characteristics of Trichinella pseudospiralis.

In 1972 three new species were proposed for the genus Trichinella, which for 137 years had contained a single species, Trichinella spiralis (Owen,1835). One of these proposed species, Trichinella pseudospiralis, was markedly different from the others in that it was smaller in size, the muscle-stage larvae were not surrounded by a capsule, and it was capable of parasitizing birds. Owing to a lack of information on the normal host range, geographic distribution, biochemistry, immunology and normal variation in biological characteristics of these organisms, several authors supported the more conservative position of designating them sibling species, subspecies or races of Trichinella. The summary statement following the session on Parasite Genetics and Speciation at the 7th International Conference on Trichinellosis recommended that pseudospiralis be accepted as a new species of Trichinella. In this article George Stewart reviews the available information on the biological and immunological characteristics of T. pseudospiralis.