Superiority of the ELISA technique over parasitological methods for detection of trichinellosis in slaughtered pigs in Canada.

Trichinoscopic examination, pepsin-hydrogen chloride digestion and the ELISA assay were used in an epidemiological survey for the presence of Trichinella spiralis in slaughterhouse pigs over a period of 12 months. The first two methods failed to detect any cases of trichinellosis in sows aged between two to three years. The ELISA assay, however, detected a 2.5% prevalence amongst the 2046 blood specimens tested. Foci of T. spiralis are localized in certain regions only. The discrepancy between the results obtained is likely to be due to the low infection density, undetectable by conventional methods. It is postulated that pigs which are not confined indoors came in contact with the sylvatic strain of Trichinella which is known for low muscle invasiveness.