West Nile Virus Disease

Risks and Symptoms:
Even in areas where the virus is circulating, very few mosquitoes are infected with the virus. Even if a mosquito is infected, less than 1% of people who get bitten and become infected will get severely ill. The chances a person will become severely ill from any one mosquito bite are extremely small. Symptoms generally appear 3 to 14 days after exposure.

It is rare to catch West Nile Virus and most people who get infected do not get sick or have mild to moderate symptoms. Symptoms are similar to the flu. In rare cases, however, the disease can be fatal.

All residents of areas where West Nile virus activity has been confirmed are at risk, but people over age 50 seem to be especially vulnerable to the severe forms of disease. In rare cases, it can be fatal.

West Nile virus can cause encephalitis (inflammation of the brain) and/or meningitis (inflammation of the brain's lining). However, most infections are mild to moderate and symptoms include fever, headache, body aches, and occasionally include skin rashes and swollen lymph nodes.

More severe infections may include headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, muscle weakness or convulsions. Persons with these symptoms need to seek medical attention immediately.

West Nile Virus is a disease that is transmitted to humans by mosquitoes. It has been common in Africa, west Asia and the Middle East for decades. It first appeared in the U.S. in 1999 in New York and has traveled westward quickly. West Nile Virus has been found in Southern California.

How It Is Spread
West Nile Virus is carried long distances by infected birds and then spread locally by mosquitoes that bite these birds. Infected mosquitoes can then bite and pass the virus on to humans and animals, primarily birds and horses. There is a vaccine for horses. There is no vaccine for humans at this time. House pets do not spread the illness.

The Placer County Health Department is closely monitoring human and horse illnesses. Monitoring for the disease is being done by testing dead birds and mosquitoes. Placer County also has a sentinel flock of chickens that are tested frequently for the presence of West Nile Virus.

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	West Nile Virus Disease Risks and Symptoms: Even in areas where the virus is circulating, very few mosquitoes are infected with the virus. Even if a mosquito is infected, less than 1% of people who get bitten and become infected will get severely ill. The chances a person will become severely ill from any one mosquito bite are extremely small. Symptoms generally appear 3 to 14 days after exposure. It is rare to catch West Nile Virus and most people who get infected do not get sick or have mild to moderate symptoms. Symptoms are similar to the flu. In rare cases, however, the disease can be fatal. All residents of areas where West Nile virus activity has been confirmed are at risk, but people over age 50 seem to be especially vulnerable to the severe forms of disease. In rare cases, it can be fatal. West Nile virus can cause encephalitis (inflammation of the brain) and/or meningitis (inflammation of the brain's lining). However, most infections are mild to moderate and symptoms include fever, headache, body aches, and occasionally include skin rashes and swollen lymph nodes. More severe infections may include headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, muscle weakness or convulsions. Persons with these symptoms need to seek medical attention immediately. West Nile Virus is a disease that is transmitted to humans by mosquitoes. It has been common in Africa, west Asia and the Middle East for decades. It first appeared in the U.S. in 1999 in New York and has traveled westward quickly. West Nile Virus has been found in Southern California. How It Is Spread West Nile Virus is carried long distances by infected birds and then spread locally by mosquitoes that bite these birds. Infected mosquitoes can then bite and pass the virus on to humans and animals, primarily birds and horses. There is a vaccine for horses. There is no vaccine for humans at this time. House pets do not spread the illness. The Placer County Health Department is closely monitoring human and horse illnesses. Monitoring for the disease is being done by testing dead birds and mosquitoes. Placer County also has a sentinel flock of chickens that are tested frequently for the presence of West Nile Virus.