The scale affects our view on the identification and distribution of microbial communities in ticks
Pollet, Thomas ; Sprong, Hein ; Lejal, Emilie ; Krawczyk, Aleksandra I. ; Moutailler, Sara ; Cosson, Jean Francois ; Vayssier-Taussat, Muriel ; Estrada-Peña, Agustín - \ 2020
Parasites & Vectors 13 (2020)1. - ISSN 1756-3305 - 1 p.
Scales - Spatial - Temporal - Tick microbe interactions - Tick microbiome
Ticks transmit the highest variety of pathogens impacting human and animal health worldwide. It is now well established that ticks also harbour a microbial complex of coexisting symbionts, commensals and pathogens. With the development of high throughput sequencing technologies, studies dealing with such diverse bacterial composition in tick considerably increased in the past years and revealed an unexpected microbial diversity. These data on diversity and composition of the tick microbes are increasingly available, giving crucial details on microbial communities in ticks and improving our knowledge on the tick microbial community. However, consensus is currently lacking as to which scales (tick organs, individual specimens or species, communities of ticks, populations adapted to particular environmental conditions, spatial and temporal scales) best facilitate characterizing microbial community composition of ticks and understanding the diverse relationships among tick-borne bacteria. Temporal or spatial scales have a clear influence on how we conduct ecological studies, interpret results, and understand interactions between organisms that build the microbiome. We consider that patterns apparent at one scale can collapse into noise when viewed from other scales, indicating that processes shaping tick microbiome have a continuum of variability that has not yet been captured. Based on available reports, this review demonstrates how much the concept of scale is crucial to be considered in tick microbial community studies to improve our knowledge on tick microbe ecology and pathogen/microbiota interactions.
Anaplasma phagocytophilum evolves in geographical and biotic niches of vertebrates and ticks
Jaarsma, Ryanne I. ; Sprong, Hein ; Takumi, Katsuhisa ; Kazimirova, Maria ; Silaghi, Cornelia ; Mysterud, Atle ; Rudolf, Ivo ; Beck, Relja ; Földvári, Gábor ; Tomassone, Laura ; Groenevelt, Margit ; Everts, Reinard R. ; Rijks, Jolianne M. ; Ecke, Frauke ; Hörnfeldt, Birger ; Modrý, David ; Majerová, Karolina ; Votýpka, Jan ; Estrada-Peña, Agustín - \ 2019
Parasites & Vectors 12 (2019). - ISSN 1756-3305
Anaplasma phagocytophilum - Ixodidae - Molecular epidemiology - Network analysis - Ticks - Transmission dynamics
Background: Anaplasma phagocytophilum is currently regarded as a single species. However, molecular studies indicate that it can be subdivided into ecotypes, each with distinct but overlapping transmission cycle. Here, we evaluate the interactions between and within clusters of haplotypes of the bacterium isolated from vertebrates and ticks, using phylogenetic and network-based methods. Methods: The presence of A. phagocytophilum DNA was determined in ticks and vertebrate tissue samples. A fragment of the groEl gene was amplified and sequenced from qPCR-positive lysates. Additional groEl sequences from ticks and vertebrate reservoirs were obtained from GenBank and through literature searches, resulting in a dataset consisting of 1623 A. phagocytophilum field isolates. Phylogenetic analyses were used to infer clusters of haplotypes and to assess phylogenetic clustering of A. phagocytophilum in vertebrates or ticks. Network-based methods were used to resolve host-vector interactions and their relative importance in the segregating communities of haplotypes. Results: Phylogenetic analyses resulted in 199 haplotypes within eight network-derived clusters, which were allocated to four ecotypes. The interactions of haplotypes between ticks, vertebrates and geographical origin, were visualized and quantified from networks. A high number of haplotypes were recorded in the tick Ixodes ricinus. Communities of A. phagocytophilum recorded from Korea, Japan, Far Eastern Russia, as well as those associated with rodents had no links with the larger set of isolates associated with I. ricinus, suggesting different evolutionary pressures. Rodents appeared to have a range of haplotypes associated with either Ixodes trianguliceps or Ixodes persulcatus and Ixodes pavlovskyi. Haplotypes found in rodents in Russia had low similarities with those recorded in rodents in other regions and shaped separate communities. Conclusions: The groEl gene fragment of A. phagocytophilum provides information about spatial segregation and associations of haplotypes to particular vector-host interactions. Further research is needed to understand the circulation of this bacterium in the gap between Europe and Asia before the overview of the speciation features of this bacterium is complete. Environmental traits may also play a role in the evolution of A. phagocytophilum in ecotypes through yet unknown relationships.
The diversity–disease relationship : evidence for and criticisms of the dilution effect
Huang, Z.Y.X. ; Langevelde, F. van; Estrada-Peña, A. ; Suzán, G. ; Boer, W.F. de - \ 2016
Parasitology 143 (2016)9. - ISSN 0031-1820 - p. 1075 - 1086.
abundance - amplification effect - competence–extinction relationship - habitat fragmentation - identity effect - infection prevalence
The dilution effect, that high host species diversity can reduce disease risk, has attracted much attention in the context of global biodiversity decline and increasing disease emergence. Recent studies have criticized the generality of the dilution effect and argued that it only occurs under certain circumstances. Nevertheless, evidence for the existence of a dilution effect was reported in about 80% of the studies that addressed the diversity–disease relationship, and a recent meta-analysis found that the dilution effect is widespread. We here review supporting and critical studies, point out the causes underlying the current disputes. The dilution is expected to be strong when the competent host species tend to remain when species diversity declines, characterized as a negative relationship between species’ reservoir competence and local extinction risk. We here conclude that most studies support a negative competence–extinction relationship. We then synthesize the current knowledge on how the diversity–disease relationship can be modified by particular species in community, by the scales of analyses, and by the disease risk measures. We also highlight the complex role of habitat fragmentation in the diversity–disease relationship from epidemiological, evolutionary and ecological perspectives, and construct a synthetic framework integrating these three perspectives. We suggest that future studies should test the diversity–disease relationship across different scales and consider the multiple effects of landscape fragmentation.
International Network for Capacity Building for the Control of Emerging Viral Vector-Borne Zoonotic Diseases: Arbo-Zoonet
Ahmed, J. ; Bouloy, M. ; Ergonul, O. ; Fooks, A.R. ; Paweska, J. ; Chevalier, V. ; Drosten, C. ; Moormann, R.J.M. ; Tordo, N. ; Vatansever, Z. ; Calistri, P. ; Estrada-Pena, A. ; Mirazimi, A. ; Unger, H. ; Yin, H. ; Seitzer, U. - \ 2009
Eurosurveillance 14 (2009)12. - ISSN 1025-496X - p. 11 - 14.
congo hemorrhagic-fever - west-nile-virus - epidemic - outbreak - romania - horses
Arboviruses are arthropod-borne viruses, which include West Nile fever virus (WNFV), a mosquito-borne virus, Rift Valley fever virus (RVFV), a mosquito-borne virus, and Crimean-Congo haemorrhagic fever virus (CCHFV), a tick-borne virus. These arthropod-borne viruses can cause disease in different domestic and wild animals and in humans, posing a threat to public health because of their epidemic and zoonotic potential. In recent decades, the geographical distribution of these diseases has expanded. Outbreaks of WNF have already occurred in Europe, especially in the Mediterranean basin. Moreover, CCHF is endemic in many European countries and serious outbreaks have occurred, particularly in the Balkans, Turkey and Southern Federal Districts of Russia. In 2000, RVF was reported for the first time outside the African continent, with cases being confirmed in Saudi Arabia and Yemen. This spread was probably caused by ruminant trade and highlights that there is a threat of expansion of the virus into other parts of Asia and Europe. In the light of global warming and globalisation of trade and travel, public interest in emerging zoonotic diseases has increased. This is especially evident regarding the geographical spread of vector-borne diseases. A multi-disciplinary approach is now imperative, and groups need to collaborate in an integrated manner that includes vector control, vaccination programmes, improved therapy strategies, diagnostic tools and surveillance, public awareness, capacity building and improvement of infrastructure in endemic regions.