Dallas begins mosquito spraying to combat West Nile Virus, advising residents to stay indoors during the operation and take precautions to avoid bites and standing water.

This month, as mosquito activity reaches its peak, health officials have detected West Nile in additional Bucks County populations, the spokesperson said: one positive test in the Hulmeville/Bensalem area, and one in Quakertown. The first positive result in Philadelphia was identified at Pennypack Park in early July.