Mitochondrial and microsatellite data show close genetic relationships between Dibothriocephalus latus from South America (Argentina) and Europe (the Alpine lakes region).

The most frequent causative agent of diphyllobothriosis, a fish-borne parasitic zoonosis, is the broad fish tapeworm Dibothriocephalus latus distributed mainly throughout the Holarctic region. The larval stages of the tapeworm were also detected in native and introduced freshwater fish in several lakes in South America, particularly in the north-western Patagonia in Argentina. The main objective of the present study was to determine the genetic structure of D. latus from rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta), and brook trout (Salvelinus fontinalis) from Gutiérrez Lake and Alicura Reservoir in Argentina using the sequences of three mitochondrial genes (cox1, cob, and nad3) and six polymorphic microsatellite loci. The results were compared with the corresponding molecular data of D. latus from Europe (Switzerland and Italy; the Alpine lakes region) and Asia (Siberia, Russia). Only one concatenated haplotype identical with the con-Ha1 specific for D. latus from the Alpine lakes region was detected in all individuals from Argentina. Three different alleles were detected in five out of six analysed microsatellite loci, indicating the presence of three sets of chromosomes. The same structure of microsatellite loci was recently observed in D. latus from Switzerland and Italy, in which triploidy was previously confirmed by cytogenetic study. The data on the mitochondrial genes, the allelic structure of microsatellite loci, and the principal coordinate analysis showed close genetic relationships between D. latus from Argentina and the Alpine lakes region, thus supporting the hypothesis of the European origin of the broad fish tapeworm from South America.

Host Switching of Zoonotic Broad Fish Tapeworm (Dibothriocephalus latus) to Salmonids, Patagonia.

Diphyllobothriosis is a reemerging zoonotic disease because of global trade and increased popularity of eating raw fish. We present molecular evidence of host switching of a human-infecting broad fish tapeworm, Dibothriocephalus latus, and use of salmonids as intermediate or paratenic hosts and thus a source of human infection in South America.

Development of microsatellite loci in zoonotic tapeworm Dibothriocephalus latus (Linnaeus, 1758), Lühe, 1899 (syn. Diphyllobothrium latum) using microsatellite library screening.

The broad fish tapeworm Dibothriocephalus latus is a causative agent of human food-borne disease called diphyllobothriosis. Medical importance, scattered geographical distribution and unknown origin of D. latus in Europe and North America make this species to be an interesting model for population genetics. Microsatellite markers were originally designed by library screening using NGS approach and validated as tools for future studies on population genetics of D. latus. Out of 122 candidates selected after NGS analysis, 110 yielded PCR products of the expected size, and in 78 of them, a declared repetitive motif was confirmed by Sanger sequencing. After the fragment analysis, six loci were proved to be polymorphic and tested for observed (Ho) and expected (He) heterozygosity, and deviations from Hardy-Weinberg equilibrium (HWE). They promise future application in studies on genetic interrelationships, origin and migratory routes of this medically important emerging tapeworm.