West Nile virus infects four horses in California.

2004 JUL 24 - (NewsRx.com & NewsRx.net) -- California's first cases of horses with West Nile virus this year were confirmed in Riverside and San Bernardino counties as officials prepared for a second round of pesticide spraying in Fontana, where six humans contracted the mosquito-borne virus.

Four horses, three in Riverside and one in San Bernardino counties, were infected with West Nile and three were euthanized. A Riverside County horse that received the two-shot vaccination series survived, said Steve Lyle of the Department of Food and Agriculture.

Confirmation of the first cases of horses infected with West Nile sent owners to veterinarians and feed stores for vaccines.

"People come in and get 10 or 15 doses at a time. It goes pretty quick," Pedley Vet Tack and Feed owner Robert Ramirez said. His store has sold nearly 400 doses since it began carrying the vaccine earlier this month.

In Fontana, three trucks sprayed a 3-square-mile area with the pesticide resmethrin during a 90-minute operation one day. The application cut the number of mosquitoes roughly in half, said San Bernardino County vector ecologist Wakoli Wekesa. Officials planned another dawn spraying of the area, as well.

Northwest Mosquito and Vector Control District officials announced Friday that mosquitoes infected with the virus had been detected in the Santa Ana River bottom in the Mira Loma area and at Martha McLean Anza Narrows Park. Ground spraying at those locations was conducted Saturday.

The California State Horsemen's Association is working to organize a low-cost vaccination clinic for western Riverside County equestrians. The association's Jim Real said a similar clinic was organized in November 2002 and only 68 animals were inoculated at that time.