Prevalence of genetically determined trehalase deficiency in populations of Siberia and Russian Far East.

In order to be digested, the disaccharide trehalose needs to be cleaved by the trehalase enzyme. There were reports suggesting that trehalase deficiency was more common in high-latitude than in the temperate climate populations. New horizons were opened for the epidemiologic research of trehalase enzymopathy when it became clear that reduced trehalase activity is determined by the A allele of tTREH gene (rs2276064). The aim of this study was to analyze the frequencies of the trehalase gene alleles and genotypes among the indigenous peoples of Siberia and the Russian Far East. We genotyped 567 samples representing the indigenous peoples of Siberia and the Russian Far East and 146 samples representing Eastern Slavs as the reference dataset. We found that the frequencies of the A*TREH alleles increased to the east. The A*TREH allele frequency was 0.03 in the reference group, 0.13-0.26 in the North-West Siberian indigenous populations, 0.29-0.30 in the South Siberia, 0.43 in West Siberia, and 0.46 in the low Amur populations. The highest frequency of the A allele (0.63) was observed in the Chukchi and Koryak populations. From 1 to 5% of European origin individuals are at risk of trehalase enzymopathy. In the indigenous populations, the frequency of the A*TREH allele varies 13% to 63%, whereas the frequency of the AA*TREH genotype from 3% to 39%. Thus, the total risk of trehalase enzymopathy among the homo- and heterozygous carriers of the A*TREH allele in the studied indigenous populations may be as high as 24% to 86%.

The prevalence of helminthiases in North-Western Siberia rural indigenous and long-term resident people in 1988-89 and 2018-19.

The aim of this work was to compare the prevalence of opisthorchiasis, diphyllobothriasis, and ascariasis among the rural indigenous and long-term resident people of Khanty-Mansi Autonomous Okrug (KMAO) in the years 1988-89 and 2018-19. Helminth infections were identified by faecal microscopic examinations conducted during health check-ups. We analysed 399 medical records for years 1988-89 and 549 records for 2018-19. There were found a decrease in the prevalence of ascariasis among the indigenous people, but the region remains a hotbed of fish-transmitted helminthiases. The spread of D. latus infestation has remained close to 5% in the indigenous adults. The number of opisthorchiasis-infected children, both indigenous and non-indigenous, has increased significantly (p < 0.05). Among the indigenous adults, opisthorchiasis in 2018-19 was at as high level as in 1988-89 (57.5% vs 54.4%). The non-indigenous adults had O. felineus infestations in 2018-19 frequently than in 1988-89 (p = 0.06). The results of our study on the prevalence of helminth infection in the population of the northern Ob River basin agree with the many years average annual incidence of helminthiases in KMAO.

Comparison of Helminth Infection among the Native Populations of the Arctic and Subarctic Areas in Western Siberia Throughout History: Parasitological Researches on Contemporary and the Archaeological Resources.

The aim of this parasitological study is examining contemporary (the late 20th century) specimens of the arctic or subarctic areas in Western Siberia and comparing them with the information acquired from archaeological samples from the same area. In the contemporary specimens, we observed the parasite eggs of 3 different species: Opisthochis felineus, Ascaris lumbricoides, and Enterobius vermicularis. Meanwhile, in archaeoparasitological results of Vesakoyakha, Kikki-Akki, and Nyamboyto I burial grounds, the eggs of Diphyllobothrium and Taenia spp. were found while no nematode (soil-transmitted) eggs were observed in the same samples. In this study, we concluded helminth infection pattern among the arctic and subarctic peoples of Western Siberia throughout history as follows: the raw fish-eating tradition did not undergo radical change in the area at least since the 18th century; and A. lumbricoides or E. vermicularis did not infect the inhabitants of this area before 20th century. With respect to the Western Siberia, we caught glimpse of the parasite infection pattern prevalent therein via investigations on contemporary and archaeoparasitological specimens.