Regional and seasonal response of a West Nile virus vector to climate change

Abstract

Climate change will affect the abundance and seasonality of West Nile virus (WNV) vectors, altering the risk of virus transmission to humans. Using downscaled general circulation model output, we calculate a WNV vector's response to climate change across the southern United States using process-based modeling. In the eastern United States, Culex quinquefasciatus response to projected climate change displays a latitudinal and elevational gradient. Projected summer population depressions as a result of increased immature mortality and habitat drying are most severe in the south and almost absent further north; extended spring and fall survival is ubiquitous. Much of California also exhibits a bimodal pattern. Projected onset of mosquito season is delayed in the southwestern United States because of extremely dry and hot spring and summers; however, increased temperature and late summer and fall rains extend the mosquito season. These results are unique in being a broad-scale calculation of the projected impacts of climate change on a WNV vector. The results show that, despite projected widespread future warming, the future seasonal response of C. quinquefasciatus populations across the southern United States will not be homogeneous, and will depend on specific combinations of local and regional conditions. disease | insect | ecology P rojections of disease-related climate change impacts are currently limited and constitute a key research priority (1). During its expansion across North America, West Nile virus (WNV) led to major epidemics during the summers of 2002-2004 (2) and is now endemic in most areas. Although host-bird species behavior and viral strain temperature tolerances are critical components of WNV dynamics (2), vector ecology is also a key element of the virus ecology. Although climate and meteorological factors can moderate mosquito vector population dynamics (3, 4) and infection rates (5), the projected impacts of climate change on WNV vectors are not yet known. From a human health perspective, a better understanding of this complex system will facilitate the implementation of more effective control measures and reduce virus transmission to human populations (6).Studies relating climate to the incidence of other mosquitoborne diseases have been performed with varying success for malaria (7-9) and dengue fever (10, 11). The most effective way to study the complex feedbacks and impacts of climate change on vector populations is through dynamic modeling because it resolves some of the limitations associated with empirically based statistical techniques. These limitations include the lack of long-term and continuous mosquito surveillance data and the inappropriate extrapolation of projections from temperature and precipitation combinations outside the bounds of past measurements. Some of these issues, however, still manifest themselves in dynamic modeling because mosquito response to climate variables may change in time and between places as a result of evolutionary pressures. Limited test data from m...

Global mapping of highly pathogenic avian influenza H5N1 and H5Nx clade 2.3.4.4 viruses with spatial cross-validation

“…This observation matches earlier observations that association with eco-climatic variables were not consistently reproducible across countries and studies (Gilbert and Pfeiffer, 2012) and that H5N1 HPAI is probably not as strongly environmentally constrained as other authors have suggested (Williams and Peterson, 2009; Zhang et al, 2014). This strongly contrasts with vector-borne diseases, where clear eco-climatic boundaries of vectors can be mapped, and where climate has a strong influence on vector seasonality and population dynamics (McMichael and Lindgren, 2011; Morin and Comrie, 2013). In the case of a directly contagious disease such as avian influenza, successful transmission and clinical outbreaks have been observed over a wide range of temperature and humidity conditions (e.g.…”

Quantifying the Risk of Introduction of West Nile Virus into Great Britain by Migrating Passerine Birds

“…Furthermore, global warming would increase the suitability of the habitat for WNV in more northerly locations in Western Europe, so as WNV suitability increases in GB, the risk of establishment of WNV is also likely to increase (Paz and Semenza, ; Fischer et al., ; Schaffner and Mathis, ). However, the relationship with global warming may be detrimental to WNV vectors if temperatures and precipitation cause drying of habitats as forecast for areas of North America (Morin and Comrie, ). The impact of climate change on bird migration patterns remains less clear, but may be disruptive (Ovaskainen et al., ).…”

Climate change and the epidemiology of selected tick‐borne and mosquito‐borne diseases: update from the International Society of Dermatology Climate Change Task Force

“…For WNV, extremely high temperatures have been associated with increased incidence in Israel . Using a climate‐driven mosquito population model, investigators have noted that future climate change could lengthen the mosquito season, with a decrease in summer mosquito populations in the USA . In Volgogard, Russia, the number of WNV infections seems to be greater in the years with mild winters and hot summers .…”