Omsk Research Institute of Natural Foci Infections

Omsk, Russia

Omsk Research Institute of Natural Foci Infections

Omsk, Russia
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Krasnov B.R.,Ben - Gurion University of the Negev | Pilosof S.,Ben - Gurion University of the Negev | Stanko M.,Slovak Academy of Sciences | Morand S.,Montpellier University | And 3 more authors.
Oikos | Year: 2014

Similarity between species plays a key role in the processes governing community assembly. The co-occurrence of highly similar species may be unlikely if their similar needs lead to intense competition (limiting similarity). On the other hand, persistence in a particular habitat may require certain traits, such that communities end up consisting of species sharing the same traits (environmental filtering). Relatively little information exists on the relative importance of these processes in structuring parasite communities. Assuming that phylogenetic relatedness reflects ecological similarity, we tested whether the co-occurrence of pairs of flea species (Siphonaptera) on the same host individuals was explained by the phylogenetic distance between them, among 40 different samples of mammalian hosts (rodents and shrews) from different species, areas or seasons. Our results indicate that frequency of co-occurrence between flea species increased with decreasing phylogenetic distance between them in 37 out of 40 community samples, with 14 of these correlations being statistically significant. A meta-analysis across all samples confirmed the overall trend for closely related species to co-occur more frequently on the same individual hosts than expected by chance, independently of the identity of the host species or of environmental conditions. These findings suggest that competition between closely related, and therefore presumably ecologically similar, species is not important in shaping flea communities. Instead, if only fleas with certain behavioural, ecological and physiological properties can encounter and exploit a given host, and if phylogenetic relationships determine trait similarity among flea species, then a process akin to environmental filtering, or host filtering, could favour the co-occurrence of related species on the same host. © 2013 The Authors.


Krasnov B.R.,Ben - Gurion University of the Negev | Matthee S.,Stellenbosch University | Lareschi M.,National University of La Plata | Korallo-Vinarskaya N.P.,Omsk Research Institute of Natural Foci Infections | Vinarski M.V.,Omsk State Pedagogical University
Oikos | Year: 2010

We studied patterns of species co-occurrence in communities of ectoparasitic arthropods (ixodid ticks, mesostigmate mites and fleas) harboured by rodent hosts from South Africa (Rhabdomys pumilio), South America (Scapteromys aquaticus and Oxymycterus rufus) and west Siberia (Apodemus agrarius, Microtus gregalis, Microtus oeconomus and Myodes rutilus) using null models. We compared frequencies of co-occurrences of parasite species or higher taxa across host individuals with those expected by chance. When non-randomness of parasite co-occurrences was detected, positive but not negative co-occurrences of parasite species or higher taxa prevailed (except for a single sample of mesostigmate mites from O. rufus). Frequency of detection of non-randomness of parasite co-occurrences differed among parasite taxa, being higher in fleas and lower in mites and ticks. This frequency differed also among host species independent of parasite taxon, being highest in Microtus species and lowest in O. rufus and S. aquaticus. We concluded that the pattern of species co-occurrence in ectoparasite communities on rodent hosts is predominantly positive, depends on life history of parasites and may be affected to a great extent by life history of a host. © 2009 Oikos.


Krasnov B.R.,Ben - Gurion University of the Negev | Stanko M.,Slovak Academy of Sciences | Khokhlova I.S.,Ben - Gurion University of the Negev | Shenbrot G.I.,Ben - Gurion University of the Negev | And 3 more authors.
Oikos | Year: 2011

We asked whether (a) variation in species composition of parasite assemblages on the same host species follows a non-random pattern and (b) if so, manifestation of this non-randomness across space and time differs among parasites, hosts and scales. We assessed nestedness and its contribution to β-diversity of fleas and gamasid mite assemblages exploiting small mammals across three scales: (a) within the same region across different locations; (b) within the same location across different times and (c) across distinct geographic regions. We estimated (a) the degree of nestedness (NCOL) and (b) the proportional contribution of nestedness to the total amount of β-diversity across locations, times and regions (βNESP). In the majority of host species, parasite assemblages were nested significantly across all three scales. In mites, but not fleas, NCOL correlated with the contribution of nestedness to the total amount of β-diversity. In fleas, NCOL did not differ among assemblages at the two local scales, but was significantly lower at regional scale. In mites, NCOL was the highest in assemblages at local spatial scale. βNESP was significantly higher (a) in flea than in mite assemblages at both local scales and (b) in mite than in flea assemblages at regional scale. In fleas, βNESP was higher at both local scales, whereas in mites it was higher at both local temporal and regional scales. Sheltering habits and geographic range of a host species did not affect either NCOL or βNESP in flea assemblages, but both metrics significantly decreased with an increase of geographic range of a host species in mite assemblages. We conclude that flea and mite assemblages across host populations at smaller and larger spatial scales and at temporal scale were characterized by nestedness which, in turn, contributed to an important degree to the total amount of β-diversity of these assemblages. © 2011 The Authors.


Krasnov B.R.,Ben - Gurion University of the Negev | Mouillot D.,Montpellier University | Shenbrot G.I.,Ben - Gurion University of the Negev | Khokhlova I.S.,Ben - Gurion University of the Negev | And 3 more authors.
International Journal for Parasitology | Year: 2010

Different host species harbour parasite faunas that are anywhere from very similar to very different in species composition. A priori, the similarity in the parasite faunas of any two host species should decrease with increases in either the phylogenetic distance, the distinctness of the environments occupied or the geographical distance between these hosts. We tested these predictions using extensive data on the faunas of fleas (Insecta: Siphonaptera) and gamasid mites (Acari: Parasitiformes) parasitic on rodents across the Palaearctic. For each pair of host species, we computed the similarity in parasite faunas based on both species composition as well as the phylogenetic and/or taxonomic distinctness of parasite species. Phylogenetic distances between hosts were based on patristic distances through a rodent phylogeny, geographic distances were computed from geographic range data, and environmental dissimilarity was measured from the average climatic and vegetation scores of each host range. Using multiple regressions on distance matrices to assess the separate explanatory power of each of the three dependent variables, environmental dissimilarity between the ranges of host species emerged as the best predictor of dissimilarity between parasite faunas, especially for fleas; in the case of mites, phylogenetic distance between host species was also important. A closer look at the data indicates that the flea and mite faunas of two hosts inhabiting different environments are always different, whilst hosts living in similar environments can have either very similar or dissimilar parasite faunas. Additional tests showed that dissimilarity in flea or mite faunas between host geographic ranges was best explained by dissimilarity in vegetation, followed by dissimilarity in climatic conditions. Thus, external environmental factors may play greater roles than commonly thought in the evolution of host-parasite associations. © 2009 Australian Society for Parasitology Inc.


Krasnov B.R.,Ben - Gurion University of the Negev | Stanko M.,Slovak Academy of Sciences | Matthee S.,Stellenbosch University | Laudisoit A.,University of Antwerp | And 5 more authors.
Oecologia | Year: 2011

We studied the co-occurrence of flea species in infracommunities of 16 rodents from four regions (South Africa, Tanzania, central Europe and western Siberia) using null models, and predicted that flea co-occurrences will be expressed more strongly in male than in female hosts. We examined patterns of co-occurrence (measured as the C score) in infracommunities of fleas that are parasitic on male and female hosts by comparing co-occurrence frequencies with those expected by chance. When a significant degree of nonrandomness in flea co-occurrences was detected, it indicated aggregative infracommunity structure. In Tanzanian rodents, no significant flea co-occurrences were detected in either male or female hosts. In a South African rodent, significant flea co-occurrences were not detected in males, but were found in females in some localities. In Palaearctic rodents, significant nonrandomness was detected either equally for males and females or more frequently in males than in females. Meta-analyses demonstrated that the frequency of the detection of nonrandomness in flea co-occurrences was significantly higher in male than in female hosts. The values of the standardized effect size (SES) for the C score differed significantly among host species, but not between host genders. When the Palaearctic hosts were analyzed separately, the effects of both host gender and species appeared to be significant, with the SES values for the C score in males being smaller than those in females. The strength of the gender difference in the manifestation of flea community structure increased with increasing gender difference in flea species richness, and with decreasing gender difference in flea prevalence for the Palaearctic hosts. We conclude that male hosts are the main drivers of flea infracommunity structure. However, the manifestation of gender bias in flea community structure varies among host species, and is likely determined by the pattern of species-specific spatial behavior. © 2011 Springer-Verlag.


Korallo-Vinarskaya N.P.,Omsk Research Institute of Natural Foci Infections | Vinarski M.V.,Omsk State Pedagogical University | Khokhlova I.S.,Ben - Gurion University of the Negev | Krasnov B.R.,Ben - Gurion University of the Negev
Ecography | Year: 2013

We studied body size ratio in gamasid mites (Acari: Mesostigmata) parasitic on Palearctic small mammals at 3 hierarchical scales, namely infracommunities (an assemblage of mites harboured by an individual host), component communities (an assemblage of mites harboured by a host population), and compound communities (an assemblage of mites harboured by a host community). We used null models and asked a) whether body size distributions in these communities demonstrate non-random patterns; b) whether these patterns indicate segregation or aggregation of body sizes of coexisting species; and c) whether patterns of body size distribution are scale-dependent, that is, differ among infracommunities, component communities, and compound communities. In most mite assemblages, the observed pattern of body size distribution did not differ from that expected by chance. However, meta-analyses demonstrated that component and compound communities of gamasid mites consistently demonstrated a tendency to reduced body size overlap, while we did not find any clear trend in mite body size distribution across infracommunities. We discuss reasons for scale-dependence of body size distribution pattern in parasite communities and propose ecological and evolutionary mechanisms that allowed the reduced body size overlap in component and compound communities of ectoparasites to arise. © 2012 The Authors. Journal compilation © 2012 Nordic Society Oikos.


Krasnov B.R.,Ben - Gurion University of the Negev | Vinarski M.V.,Omsk State Pedagogical University | Korallo-Vinarskaya N.P.,Omsk Research Institute of Natural Foci Infections | Khokhlova I.S.,Ben - Gurion University of the Negev
Ecography | Year: 2013

We studied ecological correlates of body size (abundance and niche breadth) in gamasid mites parasitic on small mammals in 28 regions of the Palearctic. We predicted that smaller species would be characterized by higher abundance than larger species, all else (e.g. host species) being equal. We also predicted that host specificity of mites would decrease (that is, number of host species they use would increase) with an increase in their body size. We focused on mites collected from host bodies that include a) species that feed solely on host's blood (obligate exclusive haematophages), b) species that feed on both host's blood and small arthropods (obligate non-exclusive haematophages), and c) facultative haematophages. We expected that the relationship between body size and abundance and/or host specificity would be more pronounced in obligate exclusively haematophagous mites than for obligate non-exclusively and facultative haematophagous mites. Across all mite species across regions, mean abundance correlated negatively with body size. The same was true for obligate haematophagous species, but not for facultative haematophages. When mite communities on the same host in a location were considered, the negative body mass-abundance relationship was found in only 3 of 44 communities. Nevertheless, a meta-analytic (across host species) estimate of the slope of this relationship appeared to be significantly negative. No significant relationship between mite body size and host specificity was found in the analyses across all mite species as well as in obligate exclusive or obligate non-exclusive haematophages. However, the number of hosts used by facultative haematophagous mites decreased significantly with an increase in their body size. We explain the relationships between morphological (body size) and ecological (abundance and niche breadth) properties of ectoparasites by their interactions with hosts or physical environment. © 2013 The Author. Ecography © 2013 Nordic Society Oikos.


Pilosof S.,Ben - Gurion University of the Negev | Fortuna M.A.,EBD Group | Vinarski M.V.,Omsk State Pedagogical University | Korallo-Vinarskaya N.P.,Omsk Research Institute of Natural Foci Infections | Krasnov B.R.,Ben - Gurion University of the Negev
Journal of Animal Ecology | Year: 2013

Temporal variation in the direct and indirect influence that hosts and parasites exert on each other is still poorly understood. However, variation in species' influence due to species and interactions turnover can have important consequences for host community dynamics and/or for parasite transmission dynamics, and eventually for the risk of zoonotic diseases. We used data on a network of small mammals and their ectoparasites surveyed over 6 years to test hypotheses exploring (i) the temporal variability in direct and indirect influences species exert on each other in a community, and (ii) the differences in temporal variability of direct/indirect influences between temporally persistent (TP) and temporally intermittent species. We modelled the temporal variation in (i) direct reciprocal influence between hosts and parasites (hosts providing resources to parasites and parasites exploiting the resources of hosts), using an asymmetry index, and (ii) indirect influence among species within a community (e.g. facilitation of parasite infestation by other parasites), using betweenness centrality. We also correlated asymmetry and centrality to examine the relationship between them. Network dynamics was determined by TP species but even those species had strong among-species heterogeneity in the temporal variation of the direct/indirect effects they exerted. In addition, there was a significant positive linear correlation between asymmetry and centrality. We conclude that the temporal dynamics of host-parasite interactions is driven by TP hosts. However, even within this group of persistent species, some exhibit large temporal variation, such that the functional roles they play (e.g. in promoting parasite transmission) change over time. In addition, parasites having a large negative impact on hosts are also those facilitating the spread of other parasites through the entire host community. Our results provide new insights into community dynamics and can be applied in the management of antagonistic networks aimed at preventing disease outbreaks. © 2013 British Ecological Society.


Poleshchuk E.M.,Omsk Research Institute of Natural Foci Infections | Sidorov G.N.,Omsk Research Institute of Natural Foci Infections | Gribencha S.V.,RAS D. I. Ivanovsky Institute of Virology
Voprosy Virusologii | Year: 2013

The data about antigenic and molecular-genetic diversity of the rabies virus circulating in Russia are reviewed. Based on our studies and the literature data analysis circulation of two phylogenetic virus groups in Russia was revealed: Arctic and cosmopolitic. The Arctic group includes the subgroups of proper Arctic and Arctic-like viruses; the cosmopolitic - Central Russian, Northeastern European and steppe. It was found that the division into subgroups corresponded to the geographic distribution of rabies viruses.


Ruzek D.,Academy of Sciences of the Czech Republic | Yakimenko V.V.,Omsk Research Institute of Natural Foci Infections | Karan L.S.,Central Research Institute of Epidemiology | Tkachev S.E.,Russian Academy of Sciences
The Lancet | Year: 2010

Omsk haemorrhagic fever is an acute viral disease prevalent in some regions of western Siberia in Russia. The symptoms of this disease include fever, headache, nausea, severe muscle pain, cough, and moderately severe haemorrhagic manifestations. A third of patients develop pneumonia, nephrosis, meningitis, or a combination of these complications. The only treatments available are for control of symptoms. No specific vaccine has been developed, although the vaccine against tick-borne encephalitis might provide a degree of protection against Omsk haemorrhagic fever virus. The virus is transmitted mainly by Dermacentor reticulatus ticks, but people are mainly infected after contact with infected muskrats (Ondatra zibethicus). Muskrats are very sensitive to Omsk haemorrhagic fever virus. The introduction of this species to Siberia in the 1930s probably led to viral emergence in this area, which had previously seemed free from the disease. Omsk haemorrhagic fever is, therefore, an example of a human disease that emerged owing to human-mediated disturbance of an ecological niche. We review the biological properties of the virus, and the epidemiological and clinical characteristics of Omsk haemorrhagic fever. © 2010 Elsevier Ltd.

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