Introduction

The territory of the Russian Federation is up to 17000000km2 in size. Russia occupies the main portion of the northern part of the Eastern Hemisphere, with Finland, a tip of Norway in the west and a bit of Alaska in the east. Sixty-eight per cent of the territory of Russia belongs to northern regions according to geographical, climatic, and ethnographic criteria. The northern regions of Russia include the Arctic and Subarctic zones with Arctic deserts, tundra, forest-tundra, and taiga. The population of the northern territories of the country slightly exceeds 12 million subjects, 3.5 million of whom are children. Indigenous ethnic minorities (aboriginal) make up about 180 000 inhabitants with 62 200 children (Federal Programme 'Children of the North', 1995-2000). The Russian North is a great bank of natural resources - gas, oil, coal, diamonds, gold, nickel, uranium, etc. Many industrial centres were created in the European North, in Ural, and Siberia in the past decades. Oil and gas fields have been developing during the last three decades in the extreme northern territories of the eastern part of the country. Several big hydroelectric stations and water reservoirs were built in the Eastern Siberia in the 1960s and 1970s.

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The transmission and the high prevalence of zoonotic parasitic infections are determined by the vast river basins, habitable for intermediate hosts of parasitic helminthes and by a continental climate with a high summer temperature in most of the northern regions. These conditions are sufficient for the development of larval forms of parasites. The social factor - the habit of consuming raw meat and raw fish is equally important. Therefore, the widespread zoonotic helminthic infections in man are food borne. Soil-transmitted intestinal helminthiases are of a rather low incidence on the outskirts of 60°N or are focused around heated agriculture complexes and greenhouses where eggs of geoghelminthes are able to develop (Lebedev et al. 1996). Contagious helminthic infections (enterobiasis, hymenolepiasis) are spread in communities, especially in children. A survey was conducted by the Martsinovsky Institute of Medical Parasitology and Tropical Medicine (the Martsinovsky Institute) in the six administrative northern territories in 1995-1996, where 4009 subjects (children and adults) were examined. It was demonstrated that up to 25.7% of persons had enterobiasis and 19.3% had other intestinal helminthiases (ascariasis, trichuriasis, or hymenolepiasis). Seroprevalence of toxocarosis in children and adults revealed in enzyme linked immunosorbent assay (ELISA) test was 2.6-5% in the Subarctic regions and 7.3-47.6% around 55-57° N altitude (Tomsk region) (Report for the Federal Programme 'Children of the North', 1996). There are no vector-borne parasitic infections in the Russian North. Malaria that was registered in the 1920s, in the European part of the country up to Archangelsk (Dobreitser 1924; Sergiev et al. 1968) is now absent even in its southern regions (imported cases only). Giardiasis and toxoplasmosis are the only protozoa infections officially registered in the population of the Russian North, but a wide range of intestinal protozoa was detected by special surveys (see below). Anyway, Lamblia intestinalis cysts were found in 4.6% tests of piped water in Tjumen and in 11.2% tests in Khabarovsk regions (Sergiev et al. 1998). The cases of cryptosporidiasis were reported from St Petersburg (Beyer et al. 1990). Data on the seroprevalence of toxoplasmosis are restricted mainly to the moderate climate zones of Russia.

Helminthiases are one of the serious problems of health care in Russia. The morbidity rate of enterobiasis in the USSR was above 1000 per hundred thousand of the population and made up about 70% of registered cases of intestinal helminthic infections. Ascariasis made up about 20%, trichiurasis about 7% and hymenolepiasis about 3% (Sergiev 1991). The number of subjects infected with O. felineus has reached 1.5 million (Sergiev 1991). The State (USSR) Programme for the Control of Parasitic Infections including opisthorchiasis and echinococcosis was partly accomplished between 1985 and 1991. Also, the morbidity rate of opisthorchiasis was still 29.6 in 1999 (Siskova et al. 2001). The control of parasitic infections in the Russian Federal Programme 'Children of the North' 1995-2000 was carried out by the Martsinovsky Institute.

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