BLUE BELL, Pa. (CBS 3) The battle against West Nile virus took to the sky Tuesday evening as planes began two nights of spraying in the Delaware Valley to target mosquitoes.
The spraying will be conducted in parts of Bucks, Delaware, Montgomery and Philadelphia counties.
"Because of the high numbers of mosquitoes and the very high numbers of West Nile positive mosquitoes, it's time to spray, (time) to control the situation before it crosses over into the human population," Kevin Smith of the Montgomery County Health Department said.
Smith said aerial treatments are recommended when five of every 1,000 mosquitoes test positive for the virus. He added that in some areas being targeted, including Norristown, the number has tripled.
"These are the highest numbers that we have ever seen with regards to positive mosquitoes in the county," Smith said.
Officials said one human case of the West Nile virus has been confirmed in a 27-year-old Montgomery County woman.
Officials said the pesticide poses no danger to the public, but while it is being applied, people can stay inside.