Factors driving the circulation and possible expansion of Crimean–Congo haemorrhagic fever virus in the western Palearctic

Authors

  • A. Estrada-Peña,

    1. Department of Parasitology, Faculty of Veterinary Medicine, University of Zaragoza, Zaragoza, Spain
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  • F. Ruiz-Fons,

    1. Instituto de Investigación en Recursos Cinegéticos IREC (CSIC-UCLM-JCCM), Ciudad Real, Spain
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  • P. Acevedo,

    1. Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, Bellaterra, Spain
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  • C. Gortazar,

    1. Instituto de Investigación en Recursos Cinegéticos IREC (CSIC-UCLM-JCCM), Ciudad Real, Spain
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  • J. de la Fuente

    Corresponding author
    1. Instituto de Investigación en Recursos Cinegéticos IREC (CSIC-UCLM-JCCM), Ciudad Real, Spain
    2. Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK,, USA
    • Department of Parasitology, Faculty of Veterinary Medicine, University of Zaragoza, Zaragoza, Spain
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Correspondence

José de la Fuente, Instituto de Investigación en Recursos Cinegéticos, Ronda de Toledo s/n, 13071 Ciudad Real, Spain. E-mail: jose_delafuente@yahoo.com

Abstract

Aims

To produce a spatial risk map regarding spread of Crimean-Congo haemorrhagic fever virus (CCHFV) in the western Palearctic by linking a process-driven model of the main tick vector, Hyalomma marginatum, to a Next Generation Matrix.

Methods and Results

Process-driven model was composed of deterministic equations that simulate developmental and mortality rates of different tick stages by using temperature and atmospheric water vapour data. The model used climate data at 10-day intervals at a spatial resolution of 10 min over western Palearctic. The model estimated the basic reproduction number, R0, for CCHFV transmission by H. marginatum ticks and evaluated how changes in temperature and biological parameters may alter the geographical range of CCHFV. In particular, variation in the rate of transovarial transmission of CCHFV in the tick produced the greatest change in CCHFV circulation in the tick population. Parameters affecting the rates of tick bite, non-systemic transmission and efficiency of tick-to-tick transmission had little effect on R0. Temperature changes that affect tick development, survival and activity rates increased the suitable area for CCHFV transmission at higher latitudes in the western Palearctic.

Conclusions

Non-systemic transmission had little impact on virus transmission under all scenarios. In the area studied, increase of temperature has no impact on the routes of transmission of CCHFV. However, climate conditions favouring tick survival, which increase infected adult tick populations, together with large numbers of hosts for adults were predicted as the most likely scenario for the spread of the virus in the studied area.

Significance and Impact of the Study

The proposed framework is able to capture the dynamics and the relative contribution of the different routes (hosts, ticks) in the transmission and spread of an important pathogen affecting human health. The high contribution of the transovarial transmission route makes the process highly dependent upon suitable hosts for adult ticks, like large domestic and wild ungulates. Climate seems to have a very reduced effect on such spread.

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