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West Nile Virus

5730 Packard Avenue, Suite 100, Marysville, CA 95901

(530) 749-6366    Fax  (530) 749-6397


I.      Updates
II.    Frequently Asked Questions
III.   Reporting  Dead Birds
IV.     For Clinicians
V.   Downloads
VI.    Resources

Counts of human cases of West Nile Virus by County as well as Counts of cases in horses, dead bird counts, and sentinel mosquito samples, sentinel chicken flocks and squirrel cases updated regularly are available on California's West Nile Virus Website 


West Nile Virus activity in the Yuba-Sutter region has started.  There are positive mosquito pools and WNV-positive dead birds found in both counties.  There will be no more bird pick-up for Yuba County; however, please continue to report dead birds by calling 1-877-WNV-BIRD (1-877-968-2473) or by going here to report online.  Reporting dead birds will help the state in mapping WNV hotspots in California.


Please be reminded to continue protecting yourself from WNV by applying mosquito repellent with DEET, avoiding the outdoors during dusk and dawn and emptying out items with water where mosquitoes can breed.  For the latest updates regarding West Nile Virus activity in California, please visit California's West Nile Virus website. 


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Frequently Asked Questions (FAQs)

1.  What is West Nile Virus (WNV)?

2.  How do people and animals get West Nile Virus?

3.  What are symptoms of West Nile Virus in people?

4.  How soon do infected people get sick?

5.  How can you minimize the risk of WNV infection?

6.  How is WNV detected and monitored in California?

1.  What is West Nile Virus (WNV)?

West Nile virus (WNV) is a mosquito-borne disease that is common in Africa, west Asia, the Middle East, and more recently, North America. Human infection with WNV may result in serious illness. Experts believe WNV is established as a seasonal epidemic in North America that flares up in the summer and continues into the fall.

2.  How do people and animals get West Nile Virus?

West Nile Virus is transmitted to people and animals by infected mosquitoes.  Only certain species of mosquitoes carry the virus and very few mosquitoes are actually infected.  A mosquito first acquires the infection by feeding on a bird with virus in its blood.  The virus lives in the mosquito and is transmitted to a new host in the mosquito's saliva when the insect bites a person or animal.  Human-to human transmission of WNV generally does not occur.  West Nile Virus can also be transmitted via blood transfusion, transplants or mother to child.  All donated blood is checked for WNV before being used. The risk of getting WNV through blood transfusions and organ transplants is very small, and should not prevent people who need surgery from having it. Transmission during pregnancy from mother to baby or transmission to an infant via breastfeeding is extremely rare.

3.  What are symptoms of West Nile Virus in people?

Most people who are infected with WNV have no symptoms whatsoever.  However, of those who become ill, symptoms can include fever, headache, nausea body aches, mild skin rash, or swollen lymph nodes.  In few cases, the disease will progress to encephalitis (inflammation of the brain).  The time between the mosquito bite and the onset of illness, known as the incubation period, ranges from 5-15 days in humans.

4.  How soon do infected people get sick?

People typically develop symptoms from 3 to14 days after they are bitten by an infected mosquito.

5.  How can you minimize the risk of WNV infection?

 To decrease exposure to mosquitoes and the infections they may carry:

 Avoid spending time outside when mosquitoes are most active, especially dawn and dusk

 When outdoors, wear long pants, long sleeve shirts and other protective clothing

 Apply insect repellant, preferably with DEET,  according to label instructions

 Make sure that doors and windows have tight fitting screens.  Repair or replace screens that have tears and holes.

 Eliminate all sources of standing water on your property that can support mosquito breeding

 Contact your local mosquito and vector  control agency if there is a significant mosquito problem where you live or work.

6.  How is WNV detected and monitored in California?

California is well prepared to detect, monitor, and respond to WNV through ongoing collaboration between over 100 public agencies. The California surveillance system includes human and horse case detection and testing of mosquitoes, sentinel chicken flocks, and dead birds for WNV.

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What do I do if I see a dead bird?

If you find a dead bird, particularly a crow, jay, magpie, or raven, please call (877) WNV-BIRD or
  You can also go to the CA West Nile website and report online.   Do not touch the bird with bare hands!  Yuba County Animal Control and Sutter-Yuba Vector Control are no longer picking up dead birds.  Please dispose the dead bird appropriately by using gloves and making sure that the bird is wrapped properly.   Before calling the hotline, examine the bird without touching.  Make sure it is a recent death and that the bird do not show signs of decay.

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West Nile Virus is locally mandated for reporting to the Yuba County Health Department.  Please fax or mail in Confidential Morbidity Reports to the Health Department.






Public Health • 5730 Packard Avenue, Suite 100, Marysville, CA 95901 • (530)749-6366 • Fax: (530)749-6397


©2009 County of Yuba, CA