A confirmed case of West Nile virus in New York City may raise questions about what the virus means for you. If you’ve seen the headlines, here’s what you need to know: Most people infected with West Nile virus never develop symptoms, and serious illness is rare.
West Nile virus may sound alarming, but the data gives a little more perspective. About one in five people infected develop a mild illness, while fewer than one percent (one out of a hundred) develop serious neurological disease, according to the U.S. Centers for Disease Control and Prevention. Still, knowing the signs of illness and how to prevent mosquito bites can help you protect yourself and your family.
This article explains what West Nile virus is and how it spreads, symptoms to watch for, who faces the greatest risk and steps you can take to protect yourself and those around you.
Quick Takeaways
- Most people infected with West Nile virus have no symptoms.
- About one in five people develop a mild illness, while fewer than one percent develop serious neurological illness.
- Adults age 65 and older and people with weakened immune systems have a higher risk of severe illness.
- Preventing mosquito bites is the best way to reduce your risk.
What Is West Nile Virus and How Is It Transmitted?
West Nile virus is a infection that can affect people and sometimes animals as well. Mosquitoes pick up the virus when they feed on infected birds and can then spread it when they bite people or animals.
West Nile virus was first identified in the United States in 1999 after an outbreak across New York State. It has since spread across much of the country and is now considered an established mosquito-borne disease in the United States. The virus is most active during warmer months, when mosquitoes are most prevalent.
What Are the Symptoms of West Nile Virus?
Most people infected with West Nile virus do not develop any symptoms, while others develop a mild illness. Typical symptoms include:
- Fever
- Headache
- Body and muscle aches
- Joint pain
- Nausea, vomiting or diarrhea
- Skin rash
- Muscle weakness
Symptoms can develop two to 14 days after an infected mosquito bite. It is worth noting that these symptoms overlap with many common illnesses, so their presence alone does not confirm West Nile virus infection.
Most people with mild illness recover completely, although fatigue and weakness can sometimes last for weeks or months.
What Are the Signs of Severe West Nile Virus?
Severe West Nile virus disease can affect the brain and spinal cord and requires prompt medical attention.
Warning signs may include:
- High fever
- Severe headache
- Stiff neck
- Confusion or disorientation
- Severe or progressive muscle weakness
- Tremors
- Seizures
- Numbness or paralysis
- Loss of consciousness
These symptoms may indicate neuroinvasive disease, including meningitis or encephalitis. If someone develops severe neurological symptoms, they should seek immediate medical attention.
Who Is At Risk for Serious Illness?
The risk of serious illness is higher for certain people, including:
- Adults age 65 and older: The risk of serious neurological illness increases with age.
- People with certain health conditions: This includes people with cancer, diabetes, high blood pressure or kidney disease.
- People with weakened immune systems: Certain medical conditions or medications can weaken the immune system and increase the risk of severe illness.
How Is West Nile Virus Diagnosed?
If your healthcare provider suspects West Nile virus, testing can help confirm the infection.
Testing may include:
- Blood test: A blood sample is usually checked for antibodies that show your immune system has responded to West Nile virus.
- Spinal fluid test: If West Nile virus may have affected the brain or spinal cord, your doctor may test a sample of cerebrospinal fluid (CSF), the fluid surrounding the brain and spinal cord.
- Additional testing: People with weakened immune systems may need other types of testing to look for the virus itself.
Because West Nile virus can cause symptoms similar to other infections, testing can help your healthcare provider determine the cause of your illness and recommend appropriate care.
How Is West Nile Virus Treated?
There is no specific medicine to treat West Nile virus. Remember, antibiotics do not work against viruses. Most people with mild illness can recover at home with rest, fluids and medication to relieve symptoms.
People with severe illness may need to be hospitalized. Treatment focuses on managing symptoms and preventing or treating complications. This may include IV fluids, breathing support and other supportive care.
How To Prevent West Nile Virus
While there is no vaccine to prevent West Nile Virus infections, You can lower your risk by reducing your exposure to mosquitoes.
- Apply EPA-registered insect repellent containing DEET, picaridin or IR3535 when spending time outdoors.
- Wear long sleeves and pants while outside, particularly around dawn and dusk, when mosquitoes are most active. Mosquitoes can bite at other times, too, so continue to use protection whenever mosquitoes are present.
- Maintain window and door screens to limit mosquito entry into your home.
- Eliminate standing water from your property at least once a week. Mosquitoes breed in still water, including in flower pots, birdbaths, buckets and clogged gutters.
- Maintain swimming pools and other outdoor water features by keeping them clean and properly maintained.
Reducing mosquito exposure in and around your home is one of the most effective ways to lower your risk of infection.
West Nile Virus FAQs
Can West Nile virus spread from person to person?
No. You cannot get West Nile virus through casual contact, touching someone who has the virus, coughing or sneezing. It also is not spread through food or water.
Does every mosquito carry West Nile virus?
No. Most mosquitoes are not infected with West Nile virus, so just being bitten by a mosquito does not mean you will become infected.
Can West Nile virus spread in other ways besides a mosquito bite?
Very rarely. The virus has been transmitted through blood transfusions, organ transplants and from mother to baby during pregnancy, delivery or breastfeeding.
Most people who contract West Nile virus never develop symptoms, and serious illness is rare. If you develop symptoms that concern you, talk with your healthcare provider, particularly if you are at higher risk for complications. Taking simple precautions to reduce mosquito exposure can help lower your chances of infection and give you peace of mind during mosquito season.
