Placer County Reports Its First Three Human West Nile Virus Cases of 2012

Roseville, CA…A Roseville resident and two Lincoln residents have tested positive for the West Nile virus (WNV) recently, becoming the first cases in Placer County this year to have a documented infection of the disease. All three residents, two adults and one child, became ill with meningitis earlier this month, were hospitalized and tested positive for WNV, and are now recovering.

“Because West Nile infections are preventable, these cases, and the positive mosquitoes and birds found this season in western areas of the County, remind us all that we must take some simple precautions to avoid mosquito bites,” said Dr. Richard Burton, Health Officer and Director of Placer County Health and Human Services.

West Nile virus is transmitted by the bite of a mosquito, usually in the two weeks before illness. The risk of serious illness to most people is low. However, some individuals – less than 1 percent – can develop a serious neurologic illness such as encephalitis or meningitis. People 50 years of age and older have a higher chance of getting sick and are more likely to develop complications. Recent data also indicate that those with diabetes and/or hypertension are at greatest risk for serious illness.

The California Department of Public Health reported Tuesday that 44 people from 15 counties have tested positive for WNV during 2012. California’s West Nile virus website,, includes the latest information on West Nile virus activity in the state.

The Placer County Health and Human Services Department and the Placer Mosquito and Vector Control District recommend that individuals prevent exposure to mosquito bites and West Nile virus by practicing the “Three Ds”:

1. DEET – Apply insect repellent containing DEET, picaridin, oil of lemon eucalyptus or IR3535 according to label instructions. Repellents keep the mosquitoes from biting you. DEET can be used safely on infants and children 2 months of age and older.

2. DAWN AND DUSK – Mosquitoes bite in the early morning and evening so it is important to wear proper clothing and repellent if outside during these times. Make sure that your doors and windows have tight-fitting screens to keep mosquitoes out. Repair or replace screens with tears or holes.

3. DRAIN – Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property, including flower pots, old car tires, rain gutters and pet bowls. If you know of a swimming pool that is not being properly maintained, please contact the district at 888-768-2343.

Horses are vulnerable to West Nile virus, and the mortality rate for unvaccinated horses is very high. Owners should contact their veterinarians about protective immunizations. West Nile does not spread between humans and horses.

Residents are encouraged to report all dead birds and dead tree squirrels on the state website or by calling toll-free 1-877-WNV-BIRD (968-2473).