West Nile virus (WNV) first arrived to North America in 1999 and rapidly spread from New York city to much of North and South America in one decade, and has become one of the most widely distributed arboviruses in the world. The viral agent is maintained by a mosquito-bird cycle, primarily involving Culex spp. mosquitoes which transmit WNV to a variety of avian hosts and mammals, including humans (Figure 1). By a process known as amplification, this mosquito-bird cycle typically increases the virus to peak levels in late summer. In the last decade, around a million people in the United States have been estimated to have been exposed to WNV, resulting in nearly 30,000 people with clinical cases, and just over 1,000 fatalities.
Figure 1. West Nile virus transmission cycle.
Since 2005, our team of researchers have been conducting field-based research in several areas in suburban Chicago (Figure 2). We have utilized a multidisciplinary approach to studying WNV which has yielded many new insights into the transmission, amplification, and evolution of WNV.
Figure 2. Map of West Nile virus project study region with red regions indicating study sites.