(Beyond Pesticides, July 23, 2008) Aerial spraying for West Nile virus (WNv) over urban areas of Sacramento County, California has been halted for one week, after three days of spraying, in order to determine the success of the treatment. The results from a series of before-and-after mosquito trapping, dead bird testing and testing for infected mosquitoes are expected to take one week to complete before it is determined whether spraying should continue.
The Sacramento-Yolo Mosquito and Vector Control District is hoping that previous treatments were successful in reducing infected mosquitoes and that it will not need to do more aerial spraying this season. Assistant manager, Gary Goodman, indicated that the possibility of continued spraying remains uncertain, as new data from dead bird testing, mosquito trap analyses and from human cases become available.
To combat WNv, the Sacramento-Yolo district has sprayed the pesticide, Evergreen Crop Protection EC 60-6T (which contains pyrethrins) over selected urban areas. Spraying for mosquitoes over urban areas of the county started in 2005, even though aerial sprayings over agricultural fields and from the ground using trucks or hand crews have occurred for a long time. In 2005 however, WNv began spreading broadly in northern California, and Sacramento was especially hard hit. Reported human cases, which usually involve either more severe symptoms or detection during routine blood donation, peaked at 880 in California in 2005. Nineteen people statewide died of WNv that year. In 2007, there were 380 reported human cases and 21 deaths, and so far this year there have been six reported cases and no deaths, according to the California Department of Public Health. The Sacramento-Yalo area reported 182 human cases in 2005. The disease most commonly passes with no symptoms, but it can be deadly or permanently disabling.
Spraying began late last week for three consecutive days after a delay due to smoke from wildfires that have ravaged the region. WNv often appears in late July, but this year signs of infection were confirmed earlier, with the first dead bird that tested positive for WNv found in March in the Sacramento-Yalo area. The public is now being urged to take precautions. Along with eliminating sources of standing water where mosquitoes breed, including abandoned pools and spas, the district is encouraging people to wear long sleeves and pants and mosquito repellant if they venture out at dawn or dusk, when mosquito activity is at its peak.
TAKE ACTION: To learn more about protecting yourself from mosquitoes and WNv this summer, read our factsheet, â€śHow to Repel Mosquitoes Safely.â€ť and visit Beyond Pesticidesâ€™ West Nile Virus/Mosquito Management program page.
Source: Sacramento Bee