Detection of trichinellosis in pigs by artificial digestion and enzyme immunoassay

The objective of this study was to demonstrate the reliability of current and proposed methods for the inspection of swine and other species for infection with the parasite Trichinella spiralis. Five groups of pigs were infected with doses of 2500, 500, 100, 50, and 20 T. spiralis larvae to establish moderate and low-level infections. Pigs were bled periodically during the study for samples to be tested by enzyme immunoassay (EIA). At the conclusion of the study, pigs were slaughtered and tissues collected for analyses of worm burdens and for comparison of digestion testing methods. Comparisons of pooled sample digestion methods were made using inspection methods prescribed by European Union Directives and the USDA, Code of Federal Regulations. Pooled sample digestion testing using 1-g samples was effective for detecting pigs with larval densities of > 10 larvae per gram (LPG) of tissue but only partially effective for pigs with infections of <3 LPG. Pooled sample digestion testing using 5-g samples detected all pigs with infection levels > 1 LPG. The EIA detected all T. spiralis-infected pigs, but did not detect infections in some pigs until 49 days after inoculation. These results demonstrate that the pooled sample digestion method using a 5-g sample size is the most effective inspection method for reducing the risk of human exposure to T. spiralis in pork.