What are the symptoms of WNV?
No symptoms in most people.
About 4 out of 5 people who are infected with WNV don't have any symptoms and most likely don't know they have or had WNV.
Milder symptoms in some people.
About 1 out of 5 people who are infected with WNV will have symptoms including:
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Fever
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Headache
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Body aches
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Nausea
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Vomiting
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Skin rash
Symptoms usually start 3 to 14 days after being bitten by an infected mosquito. Most symptoms get better on their own and usually last only a few days, although fatigue and weakness can last for weeks or months after being sick.
Serious symptoms in a few people.
About 1 out of 150 people (less than 1%) infected with WNV will become very sick. In these cases, the virus affects the brain or nervous system and can cause encephalitis or meningitis (infection of the brain or surrounding tissue). Severe symptoms can include:
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High fever
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Headache
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Neck stiffness
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Vision loss
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Numbness
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Confusion
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Muscle weakness
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Paralysis
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Coma
These symptoms may last several weeks, and effects on the brain and nervous system may be permanent. WNV can be fatal, and each year in California, people die from WNV. About 1 out of 10 people who develop severe WNV disease affecting the brain and nervous system die.
There is no specific treatment for WNV. In more severe cases, people may need to go to the hospital where they can receive supportive care, such as IV fluids, pain management, and nursing care.
Learn more about symptoms, diagnosis, and treatment of WNV
Who is at greatest risk of getting very sick from WNV?
People 55 years of age and older are at greatest risk of getting sick from WNV and are more likely to develop serious symptoms. People with certain medical conditions (such as cancer, diabetes, hypertension, and kidney disease) and people who have received organ transplants are also at greater risk of developing severe symptoms from WNV. People in these groups should be extra careful to prevent mosquito bites and should talk to a healthcare provider if they are worried about WNV or think they have it.
āHow can WNV be prevented?
āThe best way to prevent WNV is to protect yourself from mosquito bites:ā
Defend
Apply insect repellent containing DEET, picaridin, oil of lemon eucalyptus, or IR3535 to clothes and exposed skin according to label instructions. Repellents keep mosquitoes from biting you. Also make sure doors and windows have tight-fitting screens to keep mosquitoes out of your home. If screens have tears or holes, fix or replace the screens to keep mosquitoes out.āā
Dawn and Dusk
The mosquitoes that spread WNV bite in the early morning (dawn) and the evening (dusk), so it's especially important to wear long sleeves, pants, and repellent if you are outside during these times.āāā
Draāin
Mosquitoes that spread WNV lay their eggs on standing water. To keep mosquitoes from breeding around your home, get rid of any sources of standing water around your home and property. Dump and drain any containers that hold water, including buckets, old car tires, birdbaths, and pet bowls. Swimming pools that aren't maintained can also be a breeding source for mosquitoes.