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Symptoms of West Nile Virus Can Feel Like the Flu, According to Doctors

Prevention logo Prevention 6/5/2020 Korin Miller

a insect on the ground: West Nile virus still appears in the U.S. each year. Doctors explain the symptoms of the mosquito-borne illness, and how to protect yourself from bites. © Noppharat05081977 - Getty Images West Nile virus still appears in the U.S. each year. Doctors explain the symptoms of the mosquito-borne illness, and how to protect yourself from bites. While most people in the U.S. are understandably worried about contracting COVID-19, there’s another virus that’s once again surfacing in select parts of the U.S. West Nile virus has already been identified in Florida, Michigan, and California this year, and it’s expected to show up in more areas as summer progresses.

The good news: Even though West Nile virus appears in the U.S. each year, it’s not overly common, explains William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine.

That said, it’s still the leading cause of mosquito-borne disease in the continental United States, according to the Centers for Disease Control and Prevention (CDC). Cases of the virus tend to show up in the summer and continue through the fall. Last year, 47 states and D.C. reported West Nile virus infections in people, birds, or mosquitoes, according to CDC data. Overall, 958 infections in humans were reported.

Here, everything you need to know about how West Nile spreads, the symptoms to look out for, and what you can do to prevent a nasty bite in the first place.

How does West Nile virus spread?

EM of West Nile virus © Callista Images - Getty Images EM of West Nile virus West Nile is most commonly transmitted through the bite of an infected mosquito. The blood-sucking bug carries the virus after it feeds on infected birds, and then goes on to infect people and other animals by biting them, the CDC explains.

However, in a small number of cases, West Nile has also been spread through exposure in a lab setting, blood transfusion and organ donation, and from mother to baby during pregnancy, delivery, or breastfeeding.

What are the symptoms of West Nile virus?

People who contract West Nile virus generally fall into three camps, according to Amesh A. Adalja, M.D., senior scholar at the Johns Hopkins Center for Health Security: People who develop flu-like symptoms, serious neurological complications of the virus, or no symptoms at all.

“Most people who are infected with West Nile virus do not have symptoms,” Dr. Adalja explains. But about 1 in 5 people can start to experience the following signs of infection:

West Nile virus symptoms can also overlap with those of COVID-19, Dr. Schaffner points out, but there is one major difference: West Nile doesn’t cause respiratory symptoms, like coughing or trouble breathing. If you develop the symptoms of West Nile, “it’s pretty certain you’ll be given a COVID test, too,” he says.

About 1 in 150 people infected with West Nile virus develops a serious, sometimes fatal, illness that infects the central nervous system, the CDC says. This can manifest as inflammation of the brain, called encephalitis, or inflammation of the membranes that surround the brain and spinal cord, called meningitis. Symptoms of those conditions include:

  • High fever
  • Headache
  • Stiff neck
  • Disorientation
  • Tremors
  • Convulsions
  • Muscle weakness
  • Vision loss
  • Numbness and paralysis
  • Coma

People over the age of 60 are at the greatest risk of these complications, the CDC says, along with those who have underlying medical conditions like cancer, diabetes, hypertension, and kidney disease. Recovery from this form of West Nile virus can take weeks to months, but some people have lingering side effects, Dr. Adalja says. About one in 10 people who develop the severe form of West Nile virus dies from it.

How is West Nile virus treated?

Most people with a flu-like form of West Nile virus recover completely in a few days, Dr. Adalja says, but they can suffer fatigue and weakness afterward for weeks or months.

Unfortunately, there is no vaccine or specific anti-viral medication to fight a West Nile infection. “Treatment is supportive care,” Dr. Schaffner says. That can include taking over-the-counter pain relieving medication to reduce fever and aches if you have a less severe form of the virus or hospitalization if you develop a more severe form, he says.

How to prevent mosquito bites

The best way to lower your risk of contracting West Nile virus is to avoid mosquito bites altogether, says Richard Watkins, M.D., an infectious disease physician and professor of internal medicine at the Northeast Ohio Medical University.

While that can be easier said than done, your first line of defense should be an effective insect repellent. The CDC specifically recommends repellents with the following active ingredients: DEET, picaridin, IR3535, oil lemon eucalyptus (OLE), para-menthane-diol (PMD), and 2-undecanone.

Wearing long pants and long sleeves in areas where mosquitos are common, getting rid of standing pools of water around your home, and trying to avoid peak mosquito hours (dawn and dusk) is a good idea, too, Dr. Schaffner says.

If you suspect that you or one of your loved ones has been infected with West Nile virus, call your doctor immediately. While there is no specific treatment, they should be able to help guide you on care for your particular symptoms.

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Video: Why mosquitoes choose to bite some people over others (Veuer)

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