PROSSER, Wash. -- Aerial spraying to control mosquitoes potentially carrying the West Nile virus will be conducted this evening and Wednesday morning in parts of the Lower Valley, according to the Benton County Mosquito Control Board.

A mosquito trapped near Grandview’s sewage lagoon tested positive for the virus and two more samples are likely positives, said Angela Balint, district manager.

Aerial applications are scheduled in the Mabton area and south of Grandview. The spraying will not occur over populated areas.

One in five infected people develop the symptoms of West Nile virus. Onset occurs from three to 14 days after the bite. Usually, the illness runs its course without medical intervention, but serious cases can result in neck stiffness, disorientation, coma, tremors, convulsions, paralysis and even death.