Epidemiology and Diversity of Echinococcus spp. in the Republic of Sakha, Russia
Final Report Abstract
Echinococcosis is a worldwide occurring zoonosis and is considered by the WHO as one of the most important "neglected diseases". Species and genotypes of the pathogens, Echinococcus spp., differ considerably with respect to infectivity and pathogenicity for animals and humans. For two of the most important human pathogenic species, E. multilocularis and E. canadensis, the geographic center of genetic diversity, and thus presumably their center of origin, appears to be in the Asian part of Russia. This assumption is based on individual studies with small sample sizes showing that multiple genotypes of E. multilocularis and E. canadensis occur there. Further knowledge of echinococcosis in Russia is mostly based on older studies, the majority of which have not been published internationally. It is known that both alveolar and cystic echinococcosis are widespread and common in animals and humans, but little information is available on the respective causative agents. This research project aimed to determine for the first time the prevalence of Echinococcus spp. and their genetic diversity in the Republic of Sakha. It was planned to collect and study isolates from livestock and wild animals in relevant sample sizes. Adult worms from 243 definitive hosts and cyst material from five intermediate hosts were available for the study. Analysis of the samples obtained, showed that genotype 10 of E. canadensis seems to dominate at least in southern and eastern Sakha. Only this genotype could be detected in 15 wolves, two reindeer, one red deer and one moose. Genetic analysis of the cox1 gene of 42 worm and cyst isolates, showed a high haplotype diversity with 15 different genetic variants combined with a low nucleotide diversity. For comparison, 13 G10 isolates from different Finnish intermediate hosts were analyzed, which had significantly lower diversity with only three haplotypes. These results are further evidence that this region may be the origin of E. canadensis, but further studies with a larger sample size would need to confirm this. Another exciting finding is the presence of multiple haplotypes in individual definitive hosts, suggesting a high prevalence in intermediate hosts in this region. Echinococcus multilocularis was detected in an Arctic fox, a red fox, and a wolf. Only the E. multilocularis isolates from the Arctic fox could be genotyped and the North American genotype was confirmed in northern Sakha. Due to the SARS-CoV-2 pandemic and the subsequent Ukraine war, it was not possible to study the number of isolates targeted to achieve the project goals. Nevertheless, the results obtained (high diversity & presumably high prevalence) provide new insights into the situation of Echinococcus spp. in Sakha.
