Climate effects on West Nile virus vector development and transmission risk

Although daily weather and seasonal to inter-annual climatic variability influence mosquito vector biology and risk of vector-borne disease, this information is not readily employed in disease control programs. The reasons for this disconnect between climatic information and vector management are: (1) accurate relationships between climate and infectious disease are most likely dependent upon local scale parameters that have not been related to regional climate data and (2) interaction among climatologists, entomologists, public health and vector control professionals has not been integrated at the level at which information can be developed, validated, and readily incorporated into mosquito management plans. We have recently begun a study that seeks to bridge this divide. It integrates the expertise of climatologists, entomologists, social science/risk analysis experts and public health/vector control professionals to develop a system for predicting and monitoring risk of mosquito vectors, West Nile virus (WNV) transmission, and human health risk that will be readily usable by public health professionals for decision-making. Our results thus far focus on two metropolitan New Jersey counties. We have found that from June through August climatological conditions account for between 40 and 50% of the variation in monthly average adult mosquito (Culex) trap catch. In general, high monthly precipitation totals both in the month corresponding to the catch and the previous month were associated with increased catch. However, individual heavy rainfall events tend to reduce catch. Warm temperatures exerted a positive influence on mosquito abundance in June, but were associated with a low catch in August. Linear meteorological relationships explained only a small percentage of the variations in mosquito catch during May and September.