Biology subjects

Estrada-Pena, A.

Publications and source records attributed to Estrada-Pena, A..

4 recordsLinked to original sources

bioRxiv2025

Crimean-Congo Haemorrhagic Fever Virus Circulates within Broad Ecological Networks of Ticks and Vertebrates

We produced spatial datasets of the known distribution of Orthonairovirus haemorrhagiae (formerly Crimean-Congo haemorrhagic fever virus, CCHFV) by compiling human cases, virus isolations, and serological data from humans and animals, spanning from Europe to southern Africa, with the aim on virus range modelling. Models based solely on climatic variables produced unrealistic and overly extensive predictions, overestimating suitability in northern Europe and confirming that climate alone poorly explains CCHFV range. Approaches using only tick species distributions underperformed in many parts of Africa, reflecting the complexity of vector-host interactions and the absence of a strict tick-virus association. The integration of human-biting tick distributions, livestock density, and chorotypes yielded the most robust results, accurately capturing over 90% of known occurrences, by identifying vertebrate assemblages most likely to amplify the virus while reducing dimensionality. Chorotypes, representing clusters of co-occurring hosts, enhanced model performance and improved the delineation of both the northern and African ranges limits of the virus. Our results support a generalist epidemiological model in which multiple tick species, together with a broad range of vertebrate hosts, sustain CCHFV circulation. This ecological flexibility, rather than strict vector specificity, likely explains the CCHFV wide biogeographical range and occasional lineage expansions across continents. This study provides the most comprehensive assessment to date of the abiotic and biotic determinants of the distribution of CCHFV. Although gaps remain, this study demonstrates that coupling abiotic and biotic predictors provides a more accurate and ecologically meaningful understanding of CCHFV distribution. Author SummaryCrimean-Congo haemorrhagic fever virus (CCHFV) is a tick-borne pathogen causing severe disease in humans across Africa, Asia and Europe. Understanding where the virus may circulate is crucial for anticipating outbreaks and guiding surveillance. Previous studies have mostly relied on climate-based models, assuming that temperature and humidity determine where infected ticks can prevail. However, such models often overestimate risk, predicting virus presence in regions where no cases or vectors exist. In this study, we combined climatic data with ecological information on ticks, livestock, and wildlife to create a more realistic prediction of CCHFV distribution. By incorporating host-vector interactions and vertebrate communities, our models accurately captured most known occurrences and revealed the ecological patterns underlying virus transmission. Our results suggest that CCHFV persists within broad networks of tick and vertebrate species rather than a single vector. This integrated approach offers a powerful framework to identify emerging risk areas and forms a good starting point to further improve our understanding of the ecological drivers of tickborne viral diseases.

ecology↗

bioRxiv2021

Anti-microbiota vaccines modulate the tick microbiome in a taxon-specific manner

Anti-tick microbiota vaccines have been shown to impact tick feeding but its specificity has not been demonstrated. In this study we aimed to investigate the impact of immune targeting of keystone microbiota bacteria on tick performance, and tick microbiota structure and function. Vaccination against Escherichia coli, the selected keystone taxon, increased tick engorgement weight and reduced bacterial diversity in Ixodes ricinus ticks compared to those that fed on mice immunized against Leuconostoc mesenteroides, a non-keystone taxon or mock-immunized group. The abundance of Escherichia-Shigella, but not Leuconostoc was significantly reduced in ticks fed on E. coli-immunized mice and this reduction was correlated with a significant increase in host antibodies (Abs) of the isotype IgM and IgG specific to E. coli proteins. This negative correlation was not observed between the abundance of Leuconostoc in ticks and anti-L. mesenteroides Abs in mice. We also demonstrated by co-occurrence network analysis, that immunization against the keystone bacterium restructure the hierarchy of the microbial community in ticks and that anti-tick microbiota vaccines reduced the resistance of networks to directed removal of taxa. Functional pathways analysis showed that immunization with a live bacterial vaccine can also induce taxon-specific changes in the abundance of pathways. Our results demonstrated that anti-tick microbiota vaccines can modulate the tick microbiome and that the modification is specific to the taxon chosen for host immunization. These results guide interventions for the control of tick infestations and pathogen infection/transmission.

immunology↗

bioRxiv2019

Taxon appearance from extraction and amplification steps demonstrates the value of multiple controls in tick microbiome analysis

BackgroundThe development of high throughput sequencing technologies has substantially improved analysis of bacterial community diversity, composition, and functions. Over the last decade, high throughput sequencing has been used extensively to identify the diversity and composition of tick microbial communities. However, a growing number of studies are warning about the impact of contamination brought along the different steps of the analytical process, from DNA extraction to amplification. In low biomass samples, e.g. individual tick samples, these contaminants may represent a large part of the obtained sequences, and thus generate considerable errors in downstream analyses and in the interpretation of results. Most studies of tick microbiota either do not mention the inclusion of controls during the DNA extraction or amplification steps, or consider the lack of an electrophoresis signal as an absence of contamination. In this context, we aimed to assess the proportion of contaminant sequences resulting from these steps. We analyzed the microbiota of individual Ixodes ricinus ticks by including several categories of controls throughout the analytical process: crushing, DNA extraction, and DNA amplification.\n\nResultsControls yielded a significant number of sequences (1,126 to 13,198 mean sequences, depending on the control category). Some operational taxonomic units (OTUs) detected in these controls belong to genera reported in previous tick microbiota studies. In this study, these OTUs accounted for 50.9% of the total number of sequences in our samples, and were considered contaminants. Contamination levels (i.e. the percentage of sequences belonging to OTUs identified as contaminants) varied with tick stage and gender: 76.3% of nymphs and 75% of males demonstrated contamination over 50%, while most females (65.7%) had rates lower than 20%. Contamination mainly corresponded to OTUs detected in crushing and DNA extraction controls, highlighting the importance of carefully controlling these steps.\n\nConclusionHere, we showed that contaminant OTUs from extraction and amplification steps can represent more than half the total sequence yield in sequencing runs, and lead to unreliable results when characterizing tick microbial communities. We thus strongly advise the routine use of negative controls in tick microbiota studies, and more generally in studies involving low biomass samples.

microbiology↗

bioRxiv2018

A retrospective assessment of temperature trends in northern Europe reveals a deep impact on the life cycle of Ixodes ricinus (Acarina: Ixodidae).

1. AbstractThis study modelled the changes in the development processes of the health-threatening tick Ixodes acinus in northern Europe as driven by the trends of temperature (1950-2016). I used the ECA&D dataset of temperature interpolated at a resolution of 0.25o as the base data for further calculations, which were based on a previously developed process-driven model of the tick. I used the annual accumulated temperature in the period 1950-2016 to obtain the development rates of the oviposition, incubation, larva-nymph, and nymph-adult molts. Annual values were used to ascertain the trend in development rates of each stage. The ecological division of northern Europe (LANMAP2) was used to summarize results along large regions. The temperature in the years 1950-2016 clearly increased in every area of the target territory. The largest increase was observed for a wide territory eastern to Baltic countries, north-eastern Sweden and northern Finland. The development rates of every tested life cycle process had a trend to being faster throughout the time series. Moderate to high increase of the oviposition rates (70%-100% faster) resulted in central Sweden, Baltic countries, parts of Finland, and adjacent territories of Russia. Faster (70%-90%) incubation and molting rates were consistently observed in the same territories and also in large areas of western Norway. The trend of temperature in the period 1950-2016 shows a consistent inflection point around the year 1990, when the slope of the time series of temperature drastically rose. A comparison between 1950-1990 and 1991-2016 demonstrated that annual accumulated temperature was 86% and 26% higher in the Alpine regions, 7%-8% in the Atlantic and 157%, 10% and 16% in Boreal, Continental, and Nemoral regions, respectively. It is concluded that (i) accumulated annual temperature is clearly increasing in the studied territory, (ii) changes were larger since approximately the year 1990, and (iii) these changes have a deep impact on the life cycle of the tick I. ricinus. Faster development rates could be part of the processes driving the reported spread of the tick in the target area and should be considered as a serious thread to human health.

epidemiology↗