The Pennsylvania Department of Environmental Protection announced the diagnosis Friday.
The Bucks County woman is from Falls Township, and the county is now stepping up its mosquito-eradication efforts there and in other hotspots.
New rules required that officials had to find at least 50 West Nile-infected mosquitoes in a monitoring trap before they could spray pesticides to kill adult mosquitoes, said Phil Smith, Bucks County's West Nile Virus program coordinator. Once a human being tests positive for the disease, however, that threshold drops to 25, Smith said.
"I’m setting up more sprays now based on these results," Smith said Friday.
The county already has sprayed for West Nile-infected mosquitoes in Buckingham and Warrington townships, along with Croydon and west Bristol, Smith said.
Next week, Smith and the three technicians in the Bucks County program will coordinate pesticide spraying in Falls Township on Monday and in Bensalem and Lower Southampton on Tuesday.
The application around the Bensalem Township building is particularly vital, Smith said.
"Out back, they have the outdoor movies for people and there are positive mosquitoes there," Smith said. "I want to get in there to spray before a lot of people come to the activities there."
How Do You Get It?
West Nile Virus is spread through the bite of an infected mosquito - but not all mosquitoes are carriers. The Culex species is the primary carrier.
The Asian tiger mosquito came across from New Jersey and has become a real nuisance, Smith said. It rests in bushes or hedges around houses and loves to bite people, but it doesn't carry West Nile, he said.
Though most people can't tell the difference between varieties of mosquitoes, Smith said to pay attention to when the buggers are biting.
"The Culex come out at dawn and dusk," he said. "The Asian tiger mosquito will bite during the day."
Translation: take extra precaution to avoid mosquito bites at dawn and dusk.
The Spread of West Nile
The Falls Township woman brings to eight the number of people - four men and four women - who have tested positive for West Nile so far this summer, according to Pennsylvania's West Nile Virus Control Program.
Of those eight people, three developed the milder West Nile fever, with flu-like symptoms. Five developed the more serious brain inflammation, West Nile encephalitis, or meningitis, inflammation of the membrane that surrounds the brain.
All eight were infected in August.
"This is the peak time, between now and mid-September," Smith said.