West Nile Virus Has Spread to 41 of Californias 58 Counties

SACRAMENTO West Nile virus (WNV) has been detected in 11 more counties and the number of Californians who have tested positive for the virus has climbed to 148, State Public Health Officer Dr. Richard Joseph Jackson announced today.

"The months of August and September represent the peak time of the year for transmission of West Nile virus to people from mosquitoes," Jackson said. "I urge all Californians to act now to protect themselves from mosquito bites and West Nile virus."

Tests of dead birds confirmed that WNV has now spread to Calaveras, Lake, Lassen, Mariposa, Plumas, San Luis Obispo, San Mateo, Sierra, Yolo and Yuba counties. In addition, a horse in Alpine County has tested positive for the virus. In total, 41 of the states 58 counties have detected WNV.

Of the 148 Californians with WNV infections, five have died, including two each from Los Angeles and San Bernardino counties and one from Orange County. The WNV infections were reported in the following counties: San Bernardino, 62; Los Angeles, 41; Riverside, 35; Orange, 3; Fresno, 2; Kern, 2; Imperial, 1; Tulare, 1; Yolo, 1.

WNV has also infected 64 horses, of which 33 have died. Since horses are susceptible to WNV and a vaccine for horses is available, horse owners are advised to contact their veterinarians about timely vaccinations.

In recognition of the public health threat posed by WNV, the state budget includes $977,000 in state funds to boost efforts to monitor and control the spread of WNV. The funds will be used to expand surveillance activities to enhance both detection of the virus and prompt control efforts.

Most individuals who are infected with WNV will not experience any illness. Approximately 10 percent to 15 percent of infected individuals will have only mild to moderate symptoms, such as fever, headache and body aches. Less than 1 percent of individuals will develop serious neurologic illness such as encephalitis and meningitis. The elderly and those with lowered immune systems are more susceptible to serious illness.

WNV is transmitted to humans and animals through a mosquito bite. Mosquitoes become infected when they feed on infected birds. Individuals can reduce their risk of mosquito-borne diseases by taking these precautions:

The state's current interagency surveillance system for WNV includes testing of dead birds, mosquitoes, sentinel chickens, horses and people. Jackson asked the public to assist in the extensive monitoring effort for the virus by reporting any crows, ravens, magpies and jays that have been dead for less than 48 hours. Reporting can be done online by visiting the West Nile virus Web site at http://www.westnile.ca.gov/. Individuals should take note of the bird's location and condition before calling for further instructions, including assistance with identifying the type of bird found. The bird should show no signs of decomposition or maggot infestation. While there is no evidence that people can get WNV from handling live or dead infected birds, individuals should not attempt to catch or handle them. If the local agency is unable to pick up the bird, individuals should use gloves, a shovel or newspaper to put it in a plastic bag and place it in the trash. Priority for bird testing is being given to those areas where WNV has not yet been detected.

For the year to date, WNV has been found in 1,447 dead birds, 414 "pools" of mosquitoes and 200 sentinel chickens.

Source: California Department of Health Services