There are variety of parameters that influence the WNV outbreak like - urban habitats in Northeast, agricultural habitats in the western United States, rural irrigated landscapes, increased temperature, specific precipitation patterns, several socioeconomic factors such as housing age and community drainage patterns, per capita income, and neglected swimming pool density. All these parameters are associated with WNV but a clear long time prediction model for WNV is still lacking. So, to understand and predict the now unpredictable nature of WNV, necessitates the need of WNV surveillance.
There are two different complimentary aspects of the WNV surveillance –
1) Epidemiological surveillance - quantify human disease burden with emphasis on seasonal, geographic, and demographic patterns in human morbidity and mortality.
2) Environmental surveillance – emphasizes local WNV activity in vectors and non-human vertebrate hosts before epidemic activity affecting humans.
Using human case surveillance by itself is insufficient for predicting outbreaks. It can take several weeks, from the time the person get infected to actual diagnosis of the disease and to finally report the case. Resulting in time gap and thus the human case reports lag well behind from the time