Influence of methods for Trichinella detection in pigs from endemic and non-endemic European region

A total of 1401 German and 226 Croatian pigs raised either indoors or outdoors were tested for Trichinella infection by direct and indirect detection methods. A 10 g sample of diaphragm were examined for muscle larvae by the artificial digestion method; the species was determined by multiplex polymerase chain reaction (PCR). For detection of anti-Trichinella IgG, serum samples diluted 1:100, and meat juice samples diluted 1:10, were tested by enzyme-linked immunosorbent assay. All German pigs and those Croatian pigs raised indoors proved to be Trichinella-negative by all methods. Muscle larvae were detected in a total of eleven of the Croatian pigs, which were raised on small outdoor farms. For eight isolates, PCR results demonstrated that recovered larvae were Trichinella spiralis. Anti-Trichinella-IgG was detected in serum and meat juice of digestion positive animals when the worm burdens exceeded 0.38 larvae per gram of muscle. Positive results in Croatian pigs indicate a higher risk of infection for outdoor farming in areas where Trichinella is endemic. Results of direct and indirect detection were compared and are discussed with special regard to specificity and sensitivity of methods.