28 - Symposium Introduction: The importance of environmental conditions for understanding West Nile virus dynamics

Abstract: West Nile virus (WNV) is a versatile pathogen, able to infect a wide variety of primarily avian hosts. WNV has multiple pathways for amplification and overwintering. Environmental variables have the potential to influence many of these pathways, both directly and indirectly. Temperature plays a major role in mosquito development and lifespan and WNV replication time. Precipitation determines potential breeding sites for mosquitoes. Drought may change interaction dynamics between mosquitoes, birds, and mosquitos’ predators. The effects of humidity and vapor pressure deficit on mosquito life history are understudied, but affect lifespan and behavior through desiccation and desiccation risk. In spite of these strong environmental drivers of mosquito and pathogen dynamics, recent forecasting challenges have found that models based on historical patterns have performed similarly or better than models with environmentally-informed parameters. This is likely due to non-linear relationships between environmental variables and WNV amplification and spread. An improved understanding of environmental variables will be necessary, as the future will include no-analog temperature and precipitation patterns that do not correspond to any present-day locations. In addition, better incorporation of key unmeasured variables such as avian immunity, species community, and public health responses to increased risk of cases may be necessary to improve model prediction.