Comparison of trichinelloscopy with a digestion method for the detection of Trichinella larvae in muscle tissue from naturally infected pigs with low level infections

The identification of Trichinella infection in pigs in Croatia has traditionally been done by inspection of individual carcasses. In response to outbreaks of human trichinellosis in the last decade, the Croatian Ministry of Agriculture and Forestry instituted compulsory trichinelloscopic examination of tissue from both commercially and privately slaughtered swine. The purpose of this study was to compare trichinelloscopy and artificial digestion for use in samples containing low numbers of larvae. Each assay was used to test 1769 field positive samples, 290 of which contained 6 or less larvae per gram of muscle tissue. The sensitivity and specificity of trichinelloscopy with 6 or less lpg was 43.4 and 88%, respectively. κ-Value as a measure of agreement between trichinelloscopy and artificial digestion was 0.27%. It is noteworthy that a considerable number of the 103 (52%) negative animals on trichinelloscopy contained ≥6 lpg which is enough to cause clinical trichinellosis. These findings support other studies that indicate trichinelloscopy is not a method of choice and that it is necessary to implement more sensitive procedures such as artificial digestion.