West Nile Virus Infections in California at All-Time High (Map of Cases by County)

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West Nile virus is hosted primarily by birds — and spread by mosquitos. (Getty Images)

West Nile Virus infections in mosquitoes are at their highest recorded level ever in California. Last week, 52 new human cases were reported, bringing the total to 181.

Eight people have died from the illness.

“If you’re out there at a time of day when the mosquitoes are out — particularly at dawn and dusk — the risk of being bitten with an infected mosquito is higher than it’s been in the past,” said James Watt of the California Department of Public Health.

Wear insect repellent and get rid of standing water.

The department recommends precautions like wearing insect repellent and getting rid of standing water where mosquitoes can breed.

More from a State of Health post by Brittany Patterson, whose 80-year-old grandmother contracted the virus.

West Nile virus is a neurotropic arbovirus, meaning that it is a virus spread by blood-feeding insects. In some cases the virus can infect the brain. West Nile is hosted in birds and some other small mammals and spread by mosquitoes.

It was first discovered in 1937 in the West Nile District of Uganda and the disease has long plagued other parts of the world. Here in the United States, West Nile’s tenure has been more recent. The first confirmed cases began showing up in New York in 1999. Quickly, the disease began to spread and by 2004, it had been found in every state in the landlocked U.S.

Since its appearance in California in 2003, 4007 people across the state have contracted the disease, and 145 have died, according to numbers from the California Department of Public Health. …

Most people who contract West Nile won’t know that they did. Typically it takes between two and 15 days from being bitten by an infected mosquito and contracting the virus to see symptoms. Of those who are infected with West Nile, only about one in 5 persons will show symptoms, which include include fever, headache, fatigue, muscle pain and rash.

Fewer than one percent of those who do get West Nile will develop the neuroinvasive form of the disease, in which a patient will contract a serious neurological illness such as encephalitis or meningitis. People age 50 and older have a higher chance of getting sick and are more likely to develop complications.

Of those who do contract the neuroinvasive variant of West Nile, about 10 percent die — usually the elderly and the very young, according to the Centers for Disease Control..

You can view a map of cases by California county at the state’s West Nile Virus website.

Orange County leads the state in reported cases, with 61, followed by Los Angeles County with 24 and Fresno County with 23.

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