West Nile Virus Symptoms

By Sherry Baker @SherryNewsViews
May 14, 2018

West Nile virus may cause few symptoms — and sometimes serious health problems. Know the West Nile virus symptoms and when to seek help.

West Nile virus, like Zika, dengue, yellow fever, and several other diseases, is most commonly spread by mosquitoes. If you are infected with West Nile, the odds are you’ll experience few serious symptoms. But while West Nile virus is relatively harmless for many, that’s not always the case.


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West Nile can also cause brain damage and even death. That’s why getting the facts about the disease — knowing what West Nile virus symptoms are and which ones indicate you need immediate medical care — could save your life.

First documented in Uganda in the l937, West Nile virus was later found in Europe and the Middle East, India, parts of Asia, and Australia. But it wasn’t detected in North America until l999, when West Nile virus infections turned up in New York City, causing acute inflammation of the brain in 62 people and several deaths.

Since that time, nearly 44,000 cases of West Nile virus have been reported to the Centers for Disease Control and Prevention (CDC), including over 20,000 people with neurological complications from the infection. Almost 2,000 Americans have died from the virus.

However, the CDC notes many more cases of West Nile virus have no doubt occurred but were never reported. The reason is simple: The majority of people, 70 to 80 percent, who are infected with the West Nile virus don’t feel sick. Only one in five will experience fever and other West Nile virus symptoms, and even fewer will have severe complications.

In addition to fever, the most common West Nile virus symptoms include body aches, headache, joint pains, vomiting, diarrhea, and a rash. If you experience these symptoms from the infection, you’ll likely recover completely, although you may feel tired and even weak for up to a few months, according to the CDC.

Unfortunately, others aren’t so lucky. In about one percent of those infected with West Nile, the mosquito-borne virus crosses the blood-brain barrier, the National Institute of Allergy and Infectious Disease points out. This can cause life-threatening neurologic illnesses such as encephalitis (acute inflammation of the brain) or meningitis (inflammation of the lining of the brain and spinal cord). The West Nile Virus symptoms of neurologic illness include headache, high fever, neck stiffness, disorientation, tremors, seizures, paralysis, and even coma. About one in 10 people who experience neurological symptoms from West Nile virus die, according to the CDC.

Although West Nile virus can make people of any age ill, those over 60 appear to be at the highest risk for more severe symptoms and disease. In addition, having some health conditions — including cancer, diabetes, high blood pressure, and kidney disease — also places you at an increased risk for serious illness from West Nile.

It takes about two to six days for any symptoms of West Nile virus to become apparent if you’ve been bitten by an infected mosquito, but in some cases it takes up to two weeks. If you develop West Nile virus symptoms, contact your doctor. The infection can be diagnosed with laboratory tests, a physical exam, and a health history. While there’s no specific treatment for West Nile virus, most people who are symptomatic start to feel better in a few days.

But for those with severe symptoms, it’s important to get help right away. People who have severe West Nile illness often need to be hospitalized and given intravenous (IV) fluids, according to the American Academy of Family Physicians. They may also require a ventilator and medication to help prevent other infections, such as pneumonia.

There is no vaccine available to prevent West Nile, so the best way to avoid infection with the virus is to minimize your possible exposure to mosquito bites by using insect repellent and wearing protective clothing when outdoors. And be sure to eliminate areas of standing water around your yard where mosquitoes can breed.


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March 26, 2020

Reviewed By:  

Christopher Nystuen, MD, MBA