New pieces of the Trichinella puzzle

• Trichinella consists of a complex assemblage of no less than 12 different taxa.
• Extant encapsulated Trichinella spp. appeared to within the last 20 million years.
• The Trichinella genus diverged very early in the evolution of the nematode phylum.
• Approximately 9,000 genes have been identified in the Trichinella genus.
• Trichinella spp. developed different adaptive strategies.

Contrary to our understanding of just a few decades ago, the genus Trichinella now consists of a complex assemblage of no less than nine different species and three additional genotypes whose taxonomic status remains in flux. New data and methodologies have allowed advancements in detection and differentiation at the population level which in turn have demonstrably advanced epidemiological, immunological and genetic investigations. In like manner, molecular and genetic studies have permitted us to hypothesise biohistorical events leading to the worldwide dissemination of this genus, and to begin crystalising the evolution of Trichinella on a macro scale. The identification of species in countries and continents otherwise considered Trichinella-free has raised questions regarding host adaptation and associations, and advanced important findings on the biogeographical histories of its members. Using past reviews as a backdrop, we have ventured to present an up-to-date assessment of the taxonomy, phylogenetic relationships and epidemiology of the genus Trichinella with additional insights on host species, survival strategies in nature and the shortcomings of our current understanding of the epidemiology of the genus. In addition, we have begun compiling information available to date on genomics, proteomics, transcriptomics and population studies of consequence in the hope we can build on this in years to come.

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