(KTXL) — West Nile Virus (WNV) is a disease that can infect people, horses and birds and is common throughout the United States. 

According to California health officials, WNV is the most common and serious vector-borne disease in the state. 

The disease is most commonly spread to people through a bite of an infected mosquito, according to the Center for Disease Control and Prevention. Health officials say cases of West Nile virus start around the summer and last through the fall, which is considered mosquito season. 

According to the California Department of Public Health, there have been more than 7,000 human cases and over 300 deaths reported in California since 2003. 

Through May 2023, there were only five cases of WNV in California, three of them coming from dead birds and the other two from mosquito samples. 

According to state data, the three dead birds were detected in Santa Clara County and mosquito samples were found in Los Angeles and Alameda counties.

How dangerous is WNV to people

According to the CDC, about one in five people who are infected develop a fever and other symptoms. 

However, approximately 80% of infected people will not show symptoms, according to the World Health Organization. 

According to the World Health Organization, an infection can either be asymptomatic or can lead to West Nile fever or severe West Nile disease. 

To those who become sick, symptoms may include fever, headache, tiredness, and body aches, nausea, vomiting, an occasional skin rash on the trunk of the body and swollen lymph glands. 

Health officials point out that that about 1 in 150 people infected with the virus will develop a sever form of disease. 

Serious illness can occur to people of any age, but the risk is higher for those who are over 50 years old or are immunocompromised. 

When the virus becomes severe, symptoms include a headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness and paralysis.

Symptoms develop between three to 14 days, according to health officials. 

How to reduce your risk of WNV

There isn’t a vaccine for people, but there are ways to reduce your risk of WNV.

The CDC says the risk of WNV can be reduced by using insect repellent and wearing long-shirts and pants. 

When using insect repellent, the CDC urges the use of a repellent that is registered by the Environmental Protection Agency (EPA) and has the following ingredients: 




•Oil of lemon eucalyptus



Click or tap here to find a repellent that is right for you.