West Nile virus and other zoonotic viruses in Russia: examples of emerging-reemerging situations.

Studies of the interactions of vertebrates, viruses and arthropod vectors of these viruses were monitored in terms of different ecological groups of viruses transmitted by mosquitoes and ticks in Northern Eurasia in an area encompassing more than 15 million km2. About 90 viruses were isolated, including 24 new to science. Newly recognized infections of vertebrates, including humans, were described. Many unusual epidemic situations were analysed. Permanent efforts were established to prevent bioterrorist activities and their consequences. Extensive epidemic outbreaks of West Nile fever (WNF; i.e., fever caused by West Nile virus) and Crimean-Congo hemorrhagic fever (CCHF) with unusual high mortality appeared in the last four years in southern Russia. We determined infection rates in humans, domestic and wild animals, mosquitoes and ticks from natural and synanthropic biocenoses [Editorial note: "synanthropic" means, roughly, all species living with (c.f. lice, fleas) or near people, such as in houses (c.f. house mice), parks (c.f. Rattus spp.), and the like, rather like "peridomestic", but not strictly so; "biocenosis" is the biome, the "totality of living populations in a particular habitat, which itself is only a part of the ecosystem".]. CCHF virus strains were phylogenetically similar to strains isolated in this area 35 years ago but different from Central-South-Asian and African strains. Before the outset of the current emergence of epidemic WNF, three genetic variants of this virus had been isolated in USSR, two African and one Indian. Phylogenetic analysis of complete genome sequences of epidemic strains demonstrated considerable similarity to strains from USA and Israel and differences from strains isolated in the same USSR areas 20-30 years before. In addition to strains of genotype 1, we isolated strains of second and third lineages and a strain of a fourth genetic variant. Nucleotide differences of these strains from all three genotypes was about 30%. The emerging WNF situation in Russia for the last 4 years probably has been the result of not only natural and social factors, but also to introduction of more virulent strains or by evolution of the virus.

[ West Nile fever among residents of the Astrakhan region in 2002]. / Zabolevaemost' i zarazhaemost' naseleniia Astrakhanskoi oblasti likhoradkoi Zapadnogo Nila v 2002 g.

Thirty-three persons infected with West Nile fever were detected in 2002 in the Astrakhan Region; the diagnosis was confirmed serologically and the maximal number of the infected was registered in August, same year. The indices of the specific humoral immunity varied from 3.3% to 27.1%. A monitoring determined the highest infection risk among the residents of the Volga middle delta.

[Circulation of West Nile virus (Flaviviridae, Flavivirus) and some other arboviruses in the ecosystems of Volga delta, Volga-Akhtuba flood-lands and adjoining arid regions (2000-2002)]. / Osobennosti tsirkuliatsii virusa Zapadnogo Nila (Flaviviridae, Flavivirus) i nekotorykh drugikh arbovirusov v ékosistemakh del'ty Volgi, Volgo-Akhtubinskoi poimy i sopredel'nykh aridnykh landshaftakh (2000-2002 gg.).

Comprehensive virological, serological as well as genetic studies of the ecology of West Nile Virus (WNV) as well as of some other arboviruses were undertaken in different ecosystems in the territories of the Astrakhan Region and of the Kalmyk Republic. The main carriers (mosquitoes, ticks, birds and mammals) were defined as involved in the circulation of viruses within the natural and anthropogenic biocenosis. Phylogenetic examinations of isolated strains and samples, which were positive in RT-PCR, showed an absolute predominance of genotype I virus that was most closely related to American and Israeli strains. At the same time, epidemic strains had up to 6% of nucleotide differences versus the historic strains isolated in the same region 20-30 years ago. Besides, the circulation of genotype IV was discovered; it was characterized by a lower pathogenicity, which, possibly, ensures the shaping of a pronounced immune interlayer bearing no epidemic consequences. An analysis of the study results on the WNV ecology denotes the epicenter of the endemic territory located in the middle part of the Volga delta.

[Various epidemiological principles of the spread of viral hepatitis in the Astrakhan district]. / Nekotorye epidemiologicheskie zakonomernosti rasprostraneniia virusnogo gepatita v Astrakhanskoi oblasti.

Analysis of many-year changes in the vitral hepatitis incidence in the Astrakhan region showed a significant cyclicity of the epidemic process: its incidence rose 4 times during the period of from 1957 to 1976; four of these elevations were comparatively high (in 1960, 1964, and 1974). Lately the group of children aged from 3 to 7 years has been of the greatest epidemiological significance, but at present greatest incidence of the disease fell on the group of persons aged from 8 to 14 years. This can be connected with gamma-globulin vaccinations given to children aged under 10 years. Seasonal distribution of morbidity in different are groups was about the same and reflected the general automn-winter seasonal prevalence.

[Immunoglobulin level in viral hepatitis patients]. / Uroven' immunoglobulinov u bol'nykh virusnym gepatitom.

The results of studying the dynamics of serum immunoglobulins in patients with viral hepatitis varying in severity are presented. At the acute stage of the disease pronounced shifts in the content of all the three classes of immunoglobulins were found to occur in the patients irrespective of their age. Higher levels of IgM detected in women seem to be due to the physiological peculiarities of the female organism. Gamma globulin prophylaxis, when carried out at the incubation period, has been shown to exert a negative influence on humoral immunity.