Three mosquito samples collected from the Santa Clarita Valley in the past week tested positive for West Nile Virus, a county agency said Friday.

Two mosquitoes tested positive in Newhall and one in Canyon Country, according to the Greater Los Angeles County Vector Control District, which said it was the first incidence of the virus in the two areas this year.

Countywide, the past week saw 23 dead birds and 29 mosquitoes test positive for the virus, along with another six sentinel chickens showing West Nile Virus antibodies, the agency said. No dead bird tested positive in Santa Clarita. Most of the sentinel chickens were in the Sepulveda basin.

The Vector Control district says West Nile Virus activity is “elevated” throughout the county, posing a health risk to all residents. The agency issued an advisory Friday warning people to protect themselves while outdoors over the Labor Day weekend.

Year to date, the county has collected 92 virus-positive dead birds, 278 positive mosquito samples and 13 sentinel chickens with antibodies. Totals for the state are 302 dead birds, 1,028 mosquitos and 79 sentinel chickens.

Statewide, 2011 has also seen one horse and one squirrel test positive.

Nineteen people across California, including eight in Los Angeles County,  have exhibited signs of the virus.

In addition to the year’s first positive mosquitoes in Newhall and Canyon Country, this week was also the first appearance of the virus in Canoga Park and Sun Valley, via dead birds.

Officials advise residents to take the following precautions:

1. Dump/Drain – Eliminate standing water because that’s where mosquitoes breed.

2. Dusk/Dawn – Avoid outdoor activities when mosquitoes are most active.

3. Defend – Wear insect repellent containing EPA-registered ingredients such as DEET, Picaridin or Lemon Eucalyptus Oil and long-sleeve shirts and pants when outdoors. Use properly-fitted screens free from tears on windows and doors around your home to keep mosquitoes out.

For more information or to report a dead bird or squirrel, visit www.westnile.ca.gov or call 1-877-WNV-BIRD.

Click on map below to enlarge.