5 More Have West Nile Virus

Five Fontana residents have tested positive for the West Nile virus in what health officials said Friday was a significant sign of its advance into metropolitan Southern California.

The announcement brings to six the total number of people in the state to contract the virus this year -- double the number California saw in all of 2003. All six are from San Bernardino County.

Health officials have been predicting that this summer California would see its first substantial outbreak of the virus, which has slowly moved west across the country.

No one has died from the virus in California, and the number of cases is small compared with the thousands recorded in other states over the last five years.

But state and local health officials have expressed concern over increasing numbers of West Nile-infected birds and mosquitoes in urban areas the last few months.

Mosquitoes spread the virus by feeding on infected birds, usually crows, and infecting people, horses and other animals.

Less than 1% of people infected experience major complications from the virus.

Across the country, nearly 600 people have died from West Nile disease since 1999.

The latest human cases were diagnosed earlier this week, officials said. They are a 64-year-old woman, a 19-year-old man, a 17-year-old boy and two 12-year-old boys. Doctors treated the Fontana residents in May for flu-like symptoms, including fever, muscle aches, headaches and rashes, officials said. None were hospitalized, and all have recovered.

They contracted the virus about the same time and in the same city as a 40-year-old woman who was the first confirmed California case this year. She has also recovered.

“There is an area of concentrated mosquito activity that has the virus,” said Dr. Eric Frykman, a health officer with the San Bernardino County Department of Public Health.

“We expect people in Fontana to be somewhat worried about it. Fortunately, the virus doesn’t kill everyone,” he said.

In the areas where the latest cases were found, Frykman said, the local vector control agency has been intensively cleaning stagnant and dirty water supplies, typical breeding grounds for mosquitoes.

Robert Miller, a spokesman for the California Department of Health Services, said San Bernardino County’s environment was prime habitat for mosquitoes.

“It’s a warm area; a lot of agriculture going on down there, so you have pools of water,” he said. “It doesn’t take much water” to attract mosquitoes.

Health officials are worried because West Nile cases are occurring much earlier than normal. They typically develop in August or September, but this year, dead birds infected by the virus were found as early as February.

The first discovery of West Nile in California occurred last year in remotely populated areas. That has changed. Officials have found more than 200 dead birds infected with the virus in Los Angeles County and nearly 500 across Southern California this year.

West Nile was initially detected in the United States in 1999, infecting people and animals first in New York and then making its way across the country. Last year, nearly 10,000 people were infected.

Less than 20% of people infected experience flu-like symptoms. About one in 150 human cases progress to encephalitis, swelling of the brain.

Dr. Carol Glaser, acting chief of the state health department’s viral disease laboratory, said that California has been warned for years about West Nile but that the latest human cases would make people realize how important it was to take precautions.

“When humans become infected and affected by it, that does change the equation quite a bit,” Glaser said. “Once you have human cases, then it’s a reality. It’s not just circulating in the environment out there.”

Health officials continue to stress the need to rid areas of standing water, including in potted-plant containers, tires, pools and puddles. Screens on windows should be intact and in good shape to prevent mosquitoes from entering homes.

People are encouraged to wear long sleeves and pants and insect repellent containing DEET when outside, especially during mosquitoes’ main feeding times, which is between dusk and dawn.