Molecular taxonomy, phylogeny and biogeography of nematodes belonging to the Trichinella genus

Abstract

Studying parasites of the genus Trichinella provides scientists of today many advantages. This is a group of zoonotic nematodes that circulates freely among wildlife hosts with one in particular, Trichinella spiralis that is exceptionally well adapted to domestic swine. Recent reports suggest that human infections from hunted animals are on the rise worldwide and numerous countries still experience problems with T. spiralis in their domestic food supplies. Trichinella is a genus whose members are easily propagated in the laboratories, have been used as models to investigate host-parasite relationships and parasitism among clade I organisms, and represent a poorly investigated link between the phylum Nematoda and other Metazoans. The importance of T. spiralis in better understanding the tree of life was so recognized that in 2004, its genome was carefully selected as one of only nine key non-mammalian organisms to be sequenced to completion. Since it was first discovered in 1835, this genus has expanded from being monospecific to eight species including four other genotypes of undetermined taxonomic rank. Inasmuch as discriminating morphological data have been scant, our understanding of the genus has been relegated to a compilation of molecular, biochemical and biological data. Herein, we provide a collection of information and up-to-date interpretations on the taxonomy, diagnostics, systematics, micro- and macroevolution, and the biogeographical and biohistorical reconstruction of the genus Trichinella.

Molecular identification of Trichinella britovi in martens (Martes martes) and badgers (Meles meles); new host records in Poland

“…Man usually becomes infected by the ingestion of raw or undercooked pork but also from wild game or horse products containing larvae of the nematode Trichinella. In the sylvatic cycle the infection is transmitted among wild animals, mainly carnivores (foxes, wolves, bears), but omnivores are also included (wild boars, rats) (Pozio et al 2009).…”

“…Today, at least four species have been identified in Europe: T. spiralis, T. britovi, T. nativa and T. pseudospiralis (Hurníková et al 2005, Malakauskas et al 2007, Pozio et al 2009). …”

Parasites and food: ripe for exploitation

“…With the control ofTrichinella, much of the emphasis has focused on domestic environments and the role of pigs and synanthropic hosts such as the rat in transmission. However, globally, wildlife are now seen as playing the major role in maintaining cycles of transmission [10]. Anthropogenic activities may exacerbate opportunities for spillover from wildlife to domestic foci, which may threaten biosecurity for pig producers [7].…”

The viability of Trichinella spiralis larvae in frozen pork and wild boar meat revealed by the experimental infection of laboratory mice

“…The Trichinella genus includes 8 species (T. spiralis, T. nativa, T. britovi, T. nelsoni, T. murrelli, T. pseudospiralis, T. papuae, T. zimbabwensis) and many genotypes (Trichinella T5, T6, T8, T9, T12) not yet accredited to any species. The parasite's ability to infect people worldwide is well documented (Murrell et al, 2000;Pozio & Zarlenga, 2005;Krivokapich et al, 2008;Pozio et al, 2009). Two main clades are recognized in the genus Trichinella; one that encompasses species that encapsulate in host muscle tissue, and a second that does not encapsulate following muscle cell dedifferentiation (Pozio & Zarlenga, 2005).…”