In 2014 to date, Seven dead birds in San Mateo County has tested positive for WNV. For more info on West Nile virus - , Click here for the State Website

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West Nile Virus

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Programs -> Mosquitoes -> West Nile Virus

Spraying Update For Aug 21 2014 : click here for press release

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West Nile Virus Basics:

west nile virus
West Nile Virus

What is West Nile virus?

West Nile Virus is a mosquito-borne disease that originated in Africa. It first appeared in the United States in 1999 and it moved West until it reached California in 2003. It is present throughout the year, although illness is often associated with peaks during hot summer months.

How can I get West Nile virus?

West Nile virus is transmitted through the bite of an infected mosquito. Very few mosquitoes are actually infected with West Nile virus, but it only takes one infected mosquito to bite and transmit West Nile virus. Blood transfusions and organ donation account for a small number of West Nile virus cases nationwide.

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What are the signs and symptoms of West Nile virus?

Illness associated with West Nile virus varies by the severity of symptoms: 1) Severe illness associated with nervous system malfunctions 2) An extended flu-like illness with high fever and excessive sleep 3) No illness at all.
  1. Serious Symptoms: Less than 1% (1/150) of those infected with West Nile virus will have more severe symptoms that may include: high fever, headache, neck stiffness, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness, and paralysis.
  2. Milder Symptoms: About 20% ( 1/5 ) of those infected display milder symptoms which can include: fever, headache, body aches, nausea, vomiting, and a skin rash. Symptoms generally last for a few days, although some people have been sick for several weeks.
  3. No Symptoms: About 80% (4/5) of those infected with West Nile virus have no symptoms and feel nothing at all. In this group, the body produces an antibody that attacks the virus and the individual never gets sick.

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Is there West Nile virus in San Mateo County?

Yes, West Nile virus has been found in San Mateo County.

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What is the district doing to protect you?

San Mateo County Mosquito and Vector Control District has an extensive preventative mosquito control and disease surveillance program. Mosquitofish are also available at no additional cost to be used in backyard fish ponds and swimming pools.

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How can I protect myself and my family?

Mosquitoes develop in standing water. Eliminating standing water around your home will reduce your risk of getting West Nile virus. Here are some examples of how:
  • Turn over buckets and other containers.
  • Check your sprinkler system for leaks.
  • Use mosquitofish, at no additional charge from the district, in backyard fish ponds or stagnant pools that are breeding mosquitoes.
  • Fix broken pipes.
  • Use a sump pump to remove standing water from under your home.
  • Request help if you are breeding mosquitoes.
Personal protection around your home is also helpful:
  • Wear mosquito repellents containing DEET when you are outside.
  • Place screens over windows and ensure that they are tight fitting and do not have any holes.

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Why report dead birds and squirrels?

A dead bird or squirrel may indicate the presence of West Nile virus in a specific area. The California Department of Health Services uses these reports in a risk model that assist in determining areas of high risk to humans. Testing is performed on dead birds and squirrels that meet the following criteria:

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Can my cat or dog get sick from West Nile virus?

Cats rarely get sick from West Nile virus and dogs have been known to get sick but few cases have been detected. For more information regarding West Nile virus and cats and dogs - Click Here

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Can mosquitoes transmit AIDS?

No they cannot. For more information on this - Click Here

To request Service, please call (650) 344-8592.

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Click here to find out how to protect yourself and your family from West Nile Virus

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