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1. Introduction
West Nile virus (WNV) was first reported in 1999 in New York City, NY, USA. By 2000 the disease has spread throughout the northeastern USA [1,2,3]. The virus reached Louisiana in the fall of 2001, when a dead crow in Jefferson Parish was identified as being infected with WNV [4]. By 2003, WNV infections occurred in 60 of the 64 Louisiana’s parishes. In the New Orleans metropolitan areas (Orleans and Jefferson Parishes) focal transmission activity occurs principally during mid-July [4].
Culex quinquefasciatus Say, as the main vector, with Cx. salinarius Coquillett possibly acting as a secondary vector, were incriminated in the WNV outbreak in southern Louisiana during 2002 [5,6,7]. The former mosquito species, with a feeding preference for mammals, was responsible for enzootic/epidemic transmission, especially in urban and sub-urban settings [7,8,9,10,11,12,13,14]. The primary mosquito vector showed biological and ecological resilience in space and time based on the available environmental resources. This resilience may influence the spatio-temporal distribution of the WNV vector, which may or may not bring them to the vicinity of both reservoir host(s) and human populations. Eventually this will affect the amplification and transmission cycles of WNV in areas under risk.
In New Orleans, the confluence of availability of competent mosquito vector(s), susceptible reservoir host(s), suitable natural systems and climate for both mosquitoes and host(s) enabled the autochthonous transmission of WNV with hundreds of human cases and major mortality of wild native and exotic birds [2,4]. Nonetheless, the transmission dynamics of WNV in terms of space and time in relationship to the biology, ecology of mosquito vector(s), and their biophysical systems remains unclear. In fact, the distribution, blood-feeding preference, flight range and vectorial capacity of mosquito vectors are very critical inputs for predicting the transmission cycle of this disease.
Furthermore, mosquito vectors often shift their feeding preference seasonally or spatially, depending on the availability of the blood meal source. For example, Cx. quinquefasciatus showed an opportunistic preference for blood meal. In peninsular Florida, it is responsible for an epizootic cycle and sustaining the virus circulation within reservoir host bird(s) [15,16]. However, it has been incriminated with the enzootic/epidemic transmission cycle of WNV in urban and sub-urban areas in Louisiana due to feeding preference to humans and other mammals [4,6,7,17,18,19].
Currently, most...