Molecular methods for identifying and diagnosing Trichinella; from historical perspectives to the “-omics” revolution

Abstract Diagnosis of trichinellosis and the identification of Trichinella spp. have taken many forms over the years. Given the absence of morphological characters to advance that goal, science turned to immunological, biochemical, and molecular techniques. Immunological methods have worked well for identifying Trichinella-infected hosts; however, in general, methods have not been developed for identifying individual species and genotypes other than for differentiating among the encapsulated and nonencapsulated clades. This has been hindered by the strong immunodominant tyvelose antigens that are conserved among all members of the genus. Biochemical markers, predominantly isoenzyme patterns, have been more successful at defining genotypes; however, the assays tend to be labor intensive, work best on sizeable samples, and generally require large control datasets for comparative purposes. Thus over time, the industry has turned to molecular techniques, with the earliest method, restriction fragment polymorphism, surfacing in the 1980s. Over time, species identification has followed the evolution of molecular techniques from macroscales to the identification of individual worms via next-generation sequencing. Herein we review the advancement of molecular approaches to studying Trichinella spp. not only for diagnosing and differentiating among genotypes, but also as a prelude to expanding our understanding of population genetics and the evolution of the genus.