A Bucks County woman has tested positive for West Nile virus, the eighth human case of the mosquito-borne disease identified in Pennsylvania this year.

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 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."

Bensalem was supposed to show an outdoor movie Tuesday night, but officials moved the movie to Thursday so Smith and his team could spray, he said.

The Bucks County West Nile technicians also set traps to monitor adult mosquito populations across the county, and respond to complaints about abandoned pools or ponds where mosquitoes are breeding.

They advise homeowners to eliminate stagnant, standing water - think birdbaths, pools, water features, rain buckets - where mosquitoes like to breed.

How Do You Get It?

West Nile Virus is spread through the bite of an infected mosquito. The Culex species is the primary carrier, according to the Centers for Disease Control and Prevention.

The Asian tiger mosquito came across from New Jersey and has become a real nuisance, Smith said. Named for its black and white stripes, it rests in bushes or hedges around houses and loves to bite people, but it hasn't turned up positive for West Nile in Bucks County, he said.

Though many 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 from dusk to dawn," he said. "The Asian tiger mosquito will bite during the day."

Smith advised taking extra precaution to avoid mosquito bites from dawn to dusk. Click here for an interactive tool to compare the protection of different insect repellents.

In Texas this week, the state health department announced it has found the West Nile virus in the Asian tiger mosquito there.

Nearly half of this year's human cases of West Nile have occurred in Texas, according to the CDC.

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.

That is because robins - the birds that are both a favorite target of Culex mosquitoes and an effective host of West Nile virus - have departed for other climes.

"The mosquitoes bite the robins and pick up West Nile. But now, the hundreds of robins you probably saw all May, June and parts of July have started to leave the area," Smith said, adding that the mosquitoes then have to find new targets. "Th ey prefer the birds, but once the birds leave, they’ll take you."

West Nile was first detected in New York City in 1999, and its entry into Pennsylvania in 2000 was heralded by scores of dead birds. This year, 43 states have reported cases of the infection in humans, birds or mosquitoes, according to the CDC.

Since it first appeared on U.S. shores, more than 30,000 people have been diagnosed with West Nile virus, according to the CDC. This year alone, 693 people across the country have developed the infection, and 26 have died from it. Most of the human cases so far have occurred in six states - Texas, Mississippi, Louisiana, Oklahoma, South Dakota, and California.

The other seven Pennsylvania cases were found in Lehigh, Lebanon, Centre, Lancaster and Franklin counties, and two in Delaware County.