MARINE CORPS BASE CAMP PENDLETON, Calif. -- Camp Pendleton has never had a known case of West Nile Virus, a potentially deadly agent transmitted by mosquitoes. But base health officials aren-t taking any chances.
They-re biting the mosquitoes first -- and hopefully last.
Pendleton received its first aerial application of a mosquito larvicide May 13. The substance is designed to kill mosquito larvae that could carry West Nile Virus. Larvicide will be dropped monthly via helicopter here through September.
"It-s too early to tell what the threat will be this year, but it-s expected to be equal or greater (than) last year," said Navy Lt. Cmdr. Scott McKenzie, Pendleton-s public health officer.
A mosquito pool in Orange County tested positive for the virus already this year, McKenzie added.
In 2004, the virus caused 88 deaths nationwide -- including 23 in California, according to the federal Centers for Disease Control and Prevention in Atlanta. So far, there have been no reports of human infections in 2005, McKenzie said. But the virus has been detected in 21 California counties.
Last year, 182 human infections of West Nile Virus in Orange, Riverside and San Diego counties were diagnosed.
West Nile Virus was first detected in the United States in 1999 near New York City. By 2003, the virus was showing up across the nation, according to the CDC. Mosquitoes contract the virus through infected birds. Humans become infected when bitten by an infected mosquito. There is no evidence of human-to-human transmission, health officials said.
"The key to preventing West Nile Virus is controlling the mosquito population," McKenzie said. "Right now, no public health threat has been identified, but their (mosquito) presence is being felt."
Orange, San Diego and Riverside counties also are being sprayed with larvicide in preparation for summer, said Brad Sherman, an environmental protection specialist with the Facilities Maintenance Department here.
"By getting it, we are being good neighbors, and we are protecting the Marines, sailors and family members on base," Sherman said.
The larvicide is not harmful to humans or animals, officials said. Hummingbird Inc., a Valley Center-based company, is distributing the larvicide for $175,000.
The larvicide -- not the application -- accounts for most of the cost, said Buck McLean, operations manager for Hummingbird. "The high cost is worth the quality of material we use," he said. "It-s the best."
The larvicide, which is attached to ground corncob, is dropped via helicopter into bodies of water. Twenty pounds of larvicide is used per acre. The applications ultimately will cover around 400 acres on Camp Pendleton.
Thirteen areas across base ultimately will be covered in the applications, including Lake O-Neill, the Santa Margarita River and various creeks, Sherman said.
Prime season for the virus here is May through October. Naval Hospital Preventive Medicine is conducting adult mosquito surveillance to track the number of mosquitoes on base and to determine if any have the virus, McKenzie said.
Only 20 percent of humans infected will display symptoms such as nausea, vomiting and headaches. The death rate of the virus is less than 1 percent, according to CDC Web site.
The disease mostly kills elderly victims. But an especially virulent strain of the virus prevalent in the United States can produce polio-like paralysis in even young victims, according to a report Tuesday in the San Diego Union Tribune.
Base residents can protect themselves by wearing appropriate clothing and insect repellent, McKenzie said.