Abstract
Climate change is affecting the distribution of pathogens and their arthropod vectors worldwide, particularly at northern latitudes. The distribution of Culicoides sonorensis (Diptera: Ceratopogonidae) plays a key role in affecting the emergence and spread of significant vector borne diseases such as Bluetongue (BT) and Epizootic Hemorrhagic Disease (EHD) at the border between USA and Canada. We used 50 presence points for C. sonorensis collected in Montana (USA) and south-central Alberta (Canada) between 2002 and 2012, together with monthly climatic and environmental predictors to develop a series of alternative maximum entropy distribution models. The best distribution model under current climatic conditions was selected through the Akaike Information Criterion, and included four predictors: Vapour Pressure Deficit of July, standard deviation of Elevation, Land Cover and mean Precipitation of May. This model was then projected into three climate change scenarios adopted by the IPCC in its 5th assessment report and defined as Representative Concentration Pathways (RCP) 2.6, 4.5 and 8.5. Climate change data for each predictor and each RCP were calculated for two time points pooling decadal data around each one of them: 2030 (2021–2040) and 2050 (2041–2060). Our projections showed that the areas predicted to be at moderate-high probability of C. sonorensis occurrence would increase from the baseline scenario to 2030 and from 2030 to 2050 for each RCP. The projection also indicated that the current northern limit of C. sonorensis distribution is expected to move northwards to above 53°N. This may indicate an increased risk of Culicoides-borne diseases occurrence over the next decades, particularly at the USA-Canada border, as a result of changes which favor C. sonorensis presence when associated to other factors (i.e. host and pathogen factors). Recent observations of EHD outbreaks in northern Montana and southern Alberta supported our projections and considerations. The results of this study can inform the development of cost effective surveillance programs, targeting areas within the predicted limits of C. sonorensis geographical occurrence under current and future climatic conditions.
Highlights
The geographic ranges of arthropod vectors and the diseases they transmit, are determined by host and virus availability under suitable climatic and environmental conditions [1]
In 2013 both viruses were isolated in the two westernmost provinces of Canada (EHDV in Alberta and BTV in British Columbia) raising the concern that the risk of orbivirus transmission might increase in the region [11,12,13,14]
Cross-correlation was investigated for 10 variables; Land Cover was not included because it is a nominal predictor
Summary
The geographic ranges of arthropod vectors and the diseases they transmit, are determined by host and virus availability under suitable climatic and environmental conditions [1]. Two of the most important pathogens of ungulates in North America are the Orbiviruses that cause Bluetongue Disease (BT) and Epizootic Hemorrhagic Disease (EHD). These diseases can cause high morbidity and mortality resulting in significant economic loss for the livestock industry as well as impacts on the wildlife recreation and hunting sector due to their dramatic impact on wild populations. Orbiviruses are currently not endemic in Canada, despite sporadic virus incursions of BTV and EHDV [9] in the Okanagan Valley of British Columbia and EHD outbreaks in Alberta in 1962 and in 2013 [10, 11]. Modeling the current and future distribution of C. sonorensis will help to develop targeted vector surveillance programs, contributing to EHD and BT control in this region
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
