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Title: EPIDEMIOLOGICAL INVESTIGATION OF TRICHINELLA SP. IN SWITZERLAND

Author
item GOTTSTEIN, B - UNIV BERNE, SWITZERLAND
item POZIO, E - SUPERIORE DI SANITA, ROME
item CONNOLLY, B - UNIV BERNE, SWITZERLAND
item Gamble, Howard
item ECKERT, J - UN ZURICH, SWITZERLAND
item JAKOBE, H-P - SWISS FED VET OFF, SWITZ

Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: The enzyme-linked immunosorbent assay (ELISA) is a tool which is useful for testing live pigs for trichinellosis and can also be used port- slaughter for determining trichinae infection. Switzerland is essentially free from trichinae in the domestic pig population, but the disease persists in wildlife. In this study, the ELISA test was used to sample domestic and feral pigs and foxes and the results were correlated with artificial digestion methods. The ELISA had a very low rate of positive results in pigs and no larvae were found by digestion. In wild boar and foxes the serology test had a higher rate of positives and in the case of foxes, larvae were recovered from some samples. The results indicate the ELISA is quite sensitive and may detect some very low level infections. This test is useful for field studies with digestion as a confirmatory test.

Technical Abstract: Domestic pigs in Switzerland have been considered Trichinella-free for decades, despite the occurrence of Trichinella in the wildlife cycle. In order to reevaluate the present epidemiological situation, a pilot survey was undertaken in which 11,226 domestic pigs, 356 wild boars and 452 foxes were examined for Trichinella infestation using the standard artificial digestion method in accordance with prevailing EU directives and simultaneously using a serological procedure (ELISA with E/S antigens). The serological study was extended by testing 25,239 sera from sows provide by a Swiss pig serum bank. Among domestic pigs, the digestion method yielded only negative results. In the serological study, 3 fattener pigs (0.027%) and 9 sows (0.036%) showed a weak antibody reaction to the E/S- antigen. However, based on statistical calculations for the determination of the test's threshold value, these findings were considered within the expected norm. Therefore, subject to statistical restrictions, both studies support the conclusion that Trichinella sp. does not occur within the domestic pig population in Switzerland. Owing to the sensitivity, specificity and efficiency of application, the ELISA test used proved suitable for large scale testing of slaughtered pigs. Among the fox population in Switzerland, Trichinella infestation was detected using the digestion method in 0.9% of the animals tested, the seroprevalence in the same group of foxes was 13% as determined by ELISA. The fox isolate was transferred to laboratory mice and is maintained in these animals. Subsequent RAPD fingerprint analyses identified T. britovi as the infecting species.