State health officials say a Bucks County woman has become the eighth person in the state to be infected with West Nile virus.

The mosquito-born disease has now struck five times in southeastern Pennsylvania with two cases in Delaware County, one in Lehigh, one in Bucks, and one in Lancaster counties.

Experts believe last year's mild winter, paired with a steamy summer, is ideal for growth of mosquitoes which carry West Nile virus.