The taxonomic status of Echinococcus, an important zoonotic cestode genus, has remained controversial, despite numerous attempts to revise it. Although mitochondrial DNA (mtDNA) has been the source of markers of choice for reconstructing the phylogeny of the genus, results derived from mtDNA have led to significant inconsistencies with earlier species classifications based on phenotypic analysis. Here, we used nuclear DNA markers to test the phylogenic relationships of members of the genus Echinococcus. The analysis of sequence data for 5 nuclear genes revealed a significantly different phylogeny for Echinococcus from that proposed on the basis of mitochondrial DNA sequence data, but was in agreement with earlier species classifications. The most notable results from the nuclear phylogeny were (1) E. multilocularis was placed as basal taxon, (2) all genotypes of Echinococcus granulosus grouped as a monophyletic entity, and (3) genotypes G8 and G10 clustered together. We conclude that the analysis of nuclear DNA data provides a more reliable means of inferring phylogenetic relationships within Echinococcus than mtDNA and suggest that mtDNA should not be used as the sole source of markers in future studies where the goal is to reconstruct a phylogeny that does not only reflect a maternal lineage, but aims to describe the evolutionary history at species level or higher.

In this study, we investigated the presence of the larval stage of the tapeworm Echinococcus granulosus in wild ungulates in Estonia, genetically characterized E. granulosus isolates using mitochondrial gene sequences and used the sequence data, together with those available in a public database, to infer the phylogenic relationships of E. granulosus 'genotypes' G5-G10. While 0.8% of the 2038 moose (Alces alces) examined were found to be infected with E. granulosus, the parasite was not detected in other wild ungulates, such as roe deer (Capreolus capreolus: 1044 specimens examined) and wild boar (Sus scrofa: 442 specimens). Genetic analyses of concatenated atp6, nad1 and cox1 gene (1028 bp) sequences revealed that 2 novel E. granulosus haplotypes, namely E8 (11 samples: 69%) and E10 (5 samples: 31%), grouped with E. granulosus G8 and G10, respectively, are present in Estonia. This is the first record of an E. granulosus G8 in Eurasia. Phylogenetic analyses, using 4 different methods, demonstrated with considerable statistical support that E. granulosus G6/7 forms a subgroup together with G10, whereas G8 is a sister taxon to G6/7-G10.

Carcasses of 26 wolves were collected during the 2000/2001 and 2003/2004 hunting seasons and examined for helminths. Thirteen helminth species were recorded: one trematode (Alaria alata), seven cestodes (Diphyllobothrium latum, Mesocestoides lineatus, Taenia hydatigena, Taenia multiceps, Taenia ovis, Taenia pisiformis, and Echinococcus granulosus), and five nematode species (Uncinaria stenocephala, Toxascaris leonina, Toxocara canis, Trichinella nativa, and Trichinella britovi). The most common species were A. alata and U. stenocephala. Mature Echinococcus granulosus was found and described for the first time in Estonia, and its identity verified using PCR-RFLP analysis. Sequencing a fragment of the mitochondrial DNA NADH dehydrogenase 1 (mtND1) gene showed that the E. granulosus strain from Estonia was identical to strain G10, recently characterized in reindeer and moose in Finland.

In the Baltic countries, the two zoonotic diseases, alveolar echinococcosis (AE) caused by Echinococcus multilocularis, and cystic echinococcosis (CE) caused by Echinococcus granulosus, are of increasing public health concern. Observations from Estonia, Latvia and Lithuania indicate that the distribution of both parasites is wider in the Baltics than previously expected. In this paper, we review and discuss the available data, regarding both parasitoses in animals and humans, from the Baltic countries and selected adjacent regions. The data are not easily comparable but reveal a worrisome situation as the number of human AE and CE cases is increasing. Despite improvements in diagnostics and treatment, AE has a high morbidity and mortality in the Baltic region. For the control of both zoonoses, monitoring transmission patterns and timely diagnosis in humans as well as the development of local control programs present major challenges.

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Tapeworms of the species complex of Echinococcus granulosus sensu lato (s. l.) are the cause of a severe zoonotic disease - cystic echinococcosis, which is listed among the most severe parasitic diseases in humans and is prioritized by the World Health Organization. A stable taxonomy of E. granulosus s. l. is essential to the medical and veterinary communities for accurate and effective communication of the role of different species in this complex on human and animal health. E. granulosus s. l. displays high genetic diversity and has been divided into different species and genotypes. Despite several decades of research, the taxonomy of E. granulosus s. l. has remained controversial, especially the species status of genotypes G6-G10. Here the Bayesian phylogeny based on six nuclear loci (7387 bp in total) demonstrated, with very high support, the clustering of G6/G7 and G8/G10 into two separate clades. According to the evolutionary species concept, G6/G7 and G8/G10 can be regarded as two distinct species. Species differentiation can be attributed to the association with distinct host species, largely separate geographical distribution and low level of cross-fertilization. These factors have limited the gene flow between genotypic groups G6/G7 and G8/G10, resulting in the formation of distinct species. We discuss ecological and epidemiological differences that support the validity of these species.

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