West Nile virus is a disease spread through the bites of infected mosquitoes. It’s the No. 1 mosquito-borne illness in the United States, according to the Centers for Disease Control and Prevention.
West Nile Virus Causes and Transmission
“People get West Nile virus infection from mosquitoes,” said Dr. Jason Bowling, chief epidemiologist at University Health. “You can't get West Nile virus from another person. It's specifically mosquito borne, so you have to get it from a mosquito bite.”
Symptoms of West Nile Virus
Most people (80%) infected with West Nile don’t have any symptoms, according to Bowling. About 20% of people will have mild symptoms including fever and muscle aches.
“Less than 1% of people will have severe infection with meningitis or encephalitis, which is inflammation of the brain,” Bowling said. “A very, very small number of people can progress into coma, have paralysis and even die from this novel virus infection, which is why we worry about it.”
Diagnosis and Treatment of West Nile
There is not currently a vaccine to prevent West Nile virus in people. Health care providers can diagnose West Nile with a lab test. There is no cure or treatment for West Nile, but you can take medications to reduce symptoms of fever, headache, and aches and pains.
West Nile Prevention and Safety Measures
“The best way to reduce your risk of West Nile virus infection is to prevent yourself from getting mosquito bites,” Bowling said.
You can prevent mosquito bites by:
- Using insect repellent containing DEET
- Wearing long-sleeved shirts and long pants, especially at early morning or at dusk, when mosquitoes are most active
- Removing standing pools of water around your yard or house where mosquitoes tend to breed
Pools of water can be in lots of different places. Even the small amount of water that can collect in a dish under a pot or a birdbath is enough for mosquitoes to breed, Bowling said.
Frequently Asked Questions
Is West Nile Virus seasonal?
We do see a seasonal pattern with West Nile virus infections. We tend to see it in the late summer, sometimes mid-to-late summer because that's when we see the most issues with mosquito bites and mosquitoes.
What percentage of people become severely ill from West Nile Virus?
The percentage of people that become severely ill with West Nile virus infection toward less than 1%. About 1 in 150 people can develop what we call West Nile fever with meningoencephalitis, which means inflammation of meninges, which cover your spinal cord and brain. You can have confusion, go into a coma, and worst-case scenario even die from West Nile virus infection.
Can animals be infected with West Nile Virus?
Animals can be infected by West Nile virus. The cycle of West Nile virus is actually between mosquitoes and birds, and it's only when mosquitoes bite a different animal like a horse, a dog or a person, where you start to see infection outside of that bird-mosquito cycle.
What should I do if I find a dead bird?
One of the concerns with a dead bird is potentially the bird died with West Nile virus infection. Even if it wasn't symptomatic, they could be potentially colonized with it.
It's important not to pick up a dead bird with your hands, if you can avoid it. If you do need to pick up a dead bird, so it’s out of the way of pets or children, use a plastic bag to grab and dispose of it. This will keep your hand protected while you're moving it.
Does the West Nile Virus come in waves?
We see a variation in West Nile virus infections from year to year. This is an infection we have to report to the health department so they can keep records.
Every year we see some pretty different numbers. There have been some years with high levels of West Nile virus infection. It's been a while since we've had one of those. You never know which year it's going to be.
What is the County and hospital, since they are separate entities, doing to prevent and manage West Nile virus?
There are a few things that are being done to prevent West Nile virus infections in the community. Metro Health does mosquito pool testing, so they go out and capture mosquitoes tested for West Nile virus. If they find a positive result, they increase the amount of abatement or killing mosquitoes in that area. They'll do some fogging in the early morning when mosquitoes are more active to try to reduce the number of positive mosquitoes with West Nile and the number of infections.
The hospital screens people who are donating blood to make sure they don't have West Nile virus in their blood so it's not transmitted by giving that blood product from an infected person to someone who’s not infected.
Infectious Disease Care at University Health
Learn more about infectious disease care at University Health.
