Posted: July 26, 2007

FOR IMMEDIATE RELEASE
Contact: Leigh Hall, MD
Deputy Health Officer
707-565-4400

Sonoma County Health Department Confirms First 2007 Human West Nile Virus Case

Sebastopol Resident Tests Positive for West Nile Virus

A Sonoma County man in his early twenties has been diagnosed with West Nile meningitis caused by West Nile virus (WNV), making him the county’s first reported case of the mosquito-borne illness in 2007. Positive preliminary test results were confirmed today by the State Viral and Rickettsial Disease Laboratory in Richmond, California. The man developed symptoms and sought care while visiting in another county earlier this month. He was treated for symptoms and has recovered from the illness. Prior to the onset of his symptoms, he traveled to Kern County, an area with the most human cases of WNV in California this year, making it uncertain whether or not he contracted the infection in Sonoma County.

"Summer is the peak season for West Nile virus and we are starting to see more positive cases around the State," says Dr. Leigh Hall, Deputy Health Officer for Sonoma County. "We are pleased that this case was not severe and that the man has recovered."

West Nile virus is most often transmitted to humans through a mosquito bite. Mosquitoes become infected with the virus when they feed on infected birds. Rarely it can be transmitted through a blood transfusion, organ transplant or through breastfeeding. The virus is NOT spread by person-to-person contact.

Most individuals who are infected with WNV will not experience any illness. Fewer than one out of 150 people who are bitten by an infected mosquito get severely ill, according to the Centers for Disease Control and Prevention. In most cases, people who are infected never become sick or have only mild symptoms that include fever, headache nausea, body aches, or a mild skin rash. The virus, in rare cases, causes encephalitis, meningitis, paralysis and death. The elderly and those with lowered immune systems are more susceptible to serious illness. Symptoms usually appear 2 to 14 days after exposure and can last several weeks. Individuals with severe symptoms should immediately seek medical attention for supportive care.

As of July 24th, 36 human cases of West Nile disease statewide have been detected in 8 California counties, resulting in 2 deaths, in 2007. Nine of the 36 cases were reported last week. Sonoma County has also had 2 horses diagnosed with WNV this year. "Mid to late August is the peak of the West Nile virus season, and the number of cases in California is definitely on the rise for 2007," said Hall.

"The risk of acquiring the virus is low, though it will increase over the next month or so, and we urge residents to take the necessary precautions to reduce exposure to mosquitoes and eliminate breeding grounds," Hall emphasized. He continued, "Sonoma/Marin Mosquito Vector Control District has been very active in reducing the spread of West Nile virus by preventing breeding of mosquitoes through routine abatement efforts and working with the community to identify areas conducive to mosquito breeding, such as ponds, creeks, abandoned pools or other areas of standing water. We are fortunate to have such a comprehensive mosquito abatement program in our county."

How Individuals Can Prevent West Nile Virus:

• Avoid spending time outside when mosquitoes are most active, especially at dawn and dusk.
• When outdoors, wear long pants and long-sleeved shirts.
• Use mosquito repellent with DEET according to label instructions. Products with 10-35% DEET will provide adequate protection under most conditions. For children over the age of two months, use repellent less than 30% DEET as recommended by the Academy of Pediatrics. Products with 10% are effective for about two hours; with 24%, about 5 hours. Alternatives to DEET include products with picaridin or oil of lemon eucalyptus.
• Make sure that doors and windows have tight fitting screens. Repair or replace screens that have tears or holes.
• Eliminate all sources of standing water on your property that can support mosquito breeding.
• Contact the Marin/Sonoma Mosquito and Vector Control District if there is a significant mosquito problem where you live or work at (707)285-2200.

For more information about WNV visit these websites or call the Department of Health Services Disease Control Unit at (707) 565-4567. To report dead birds, visit the State website below or call the State at (877) WNV-BIRD.

California West Nile Virus Website (www.westnile.ca.gov)

Sonoma County Public Health Preparedness West Nile Virus Information (www.sonoma-county.org/wnv)

Marin/Sonoma Mosquito & Vector Control District (www.msmosquito.com)

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