Asunto(s)
Enfermedades Transmisibles Emergentes/epidemiología , Animales , Enfermedades Transmisibles Emergentes/transmisión , Enfermedades Transmisibles Emergentes/virología , Brotes de Enfermedades/prevención & control , Vectores de Enfermedades , Genoma Viral , Virus de la Fiebre Hemorrágica de Crimea-Congo/genética , Virus de la Fiebre Hemorrágica de Crimea-Congo/aislamiento & purificación , Fiebre Hemorrágica de Crimea/epidemiología , Fiebre Hemorrágica de Crimea/transmisión , Fiebre Hemorrágica de Crimea/virología , Humanos , Virus Reordenados/aislamiento & purificación , Federación de Rusia/epidemiología , Fiebre del Nilo Occidental/epidemiología , Fiebre del Nilo Occidental/transmisión , Fiebre del Nilo Occidental/virología , Virus del Nilo Occidental/genética , Virus del Nilo Occidental/aislamiento & purificaciónRESUMEN
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.
Asunto(s)
Infecciones por Arbovirus/veterinaria , Arbovirus/aislamiento & purificación , Reservorios de Enfermedades , Vectores de Enfermedades , Fiebre del Nilo Occidental/veterinaria , Virus del Nilo Occidental/aislamiento & purificación , Virus del Nilo Occidental/fisiología , Animales , Animales Domésticos/sangre , Anticuerpos Antivirales/sangre , Infecciones por Arbovirus/sangre , Infecciones por Arbovirus/epidemiología , Infecciones por Arbovirus/virología , Aves/virología , Virus Bunyamwera/aislamiento & purificación , Culicidae/virología , Ecología , Ecosistema , Virus de la Fiebre Hemorrágica de Crimea-Congo/aislamiento & purificación , Humanos , Ixodidae/virología , Mamíferos/virología , Filogenia , Federación de Rusia/epidemiología , Thogotovirus/aislamiento & purificación , Fiebre del Nilo Occidental/sangre , Fiebre del Nilo Occidental/epidemiología , Virus del Nilo Occidental/patogenicidad , ZoonosisRESUMEN
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.