HOW LOCAL CONDITIONS AFFECT WNV SPREAD
A new study underscores how local conditions can influence the spread of disease.
Researchers at Mississippi State University did an in-depth statistical analysis of West Nile virus (WNV) encephalomyelitis incidence across the state in 2002, looking specifically at how rainfall and land cover---the amount and type of vegetation, water sources and areas developed by humans---correlated to reports of the disease at the county level.
A zoonotic disease first identified in this country in 1999, WNV is now considered endemic to the United States. Carried by birds--primarily crows and jays--WNV is transmitted by mosquitoes. Most horses exposed to the virus don’t become ill, but among the small percentage that do 30 percent die or are euthanatized. Clinical signs of infection include weakness and incoordination, muscle trembling and fever.
In analyzing data from the United States Department of Agriculture, the United States Geological Service