Ring trial on detection of Trichinella muscle larvae in pork (2004)

In the national ring trial "Detection of Trichinella muscle larvae in pork" in 2004, a total of 10 coded samples was sent to 33 laboratories of 15 Under in Germany. The 6 Trichinella-positive samples originated from two pigs which were infected experimentally with T spiralis and they were prepared as double samples with a nominal value of 8.0, 19.5 and 71.0 larvae per g of muscle tissue (1pg), respectively. The other four samples were Trichinella-negative. All samples had to be examined with a method according to the Directive 77/96/EEC. 33 laboratories examined samples with the artificial digestion by means of the magnetic stirrer method and 16 labs (48.5%) correctly classified all 10 samples. False-positive and/or false-negative results occurred in 13 laboratories (39.4%) in 1 to 2 cases. In 2 labs (6.1%) 3 samples and in 2 other laboratories (6.1%) 5 or 6 samples were not correctly identified. Out of 7 laboratories which also performed trichinoscopy 5 gained correct results in all 10 samples. 4 samples revealed false-negative in 2 labs. According to results of quantitative analysis, comprehensive differences were evaluated between nominal and actual value in case of correctly identified positive in magnetic stirrer method (8.0: 1-18; 19.5: 1-40; 71.0: 3-146) and trichinoscopy (8.0: 1-11; 19.5: 1-23; 71.0: 2-84). Possible sources of error for false-negative and false-positive results are discussed and conclusions are made for improvement of quality assurance