West Nile virus is a rare mosquito-borne illness. Most who contract it show no symptoms but it can also be serious.
Summer and fall bring with them many things to do in the great outdoors but not on that list is contracting West Nile virus.
This relatively rare illness is the leading mosquito-borne disease in the U.S., mostly spread to people by an infected mosquito’s bite.
The virus has been in the environment for some time and is everywhere in the U.S., said Jennifer Meece, Ph.D., a tick-borne disease expert who directs the Integrated Research and Development Laboratory, Marshfield Clinic Research Institute.
How do we get West Nile?
It all starts with infected birds being bitten by mosquitoes. Mosquitoes become infected and spread the virus to susceptible hosts, including more birds. This amplifies the virus which becomes infectious to more biting mosquitoes.
“Humans are considered a ‘dead end’ host when they bite us because we don’t attain high enough virus levels to infect mosquitoes when they feed on us. Most people, about 80%, with the virus do not feel sick or have symptoms,” Meece said.
About one in five people develop symptoms – fever, headache, body aches, joint pain, skin rash and swollen lymph nodes. These individuals recover but can have tiredness and other symptoms for several months after being infected.
About one in 150 people who become infected, Meece said, develop illness with severe neurological complications. Severe symptoms may be high fever, stiff neck, headache, sleepiness, disorientation, coma, tremors, convulsions, vision loss and paralysis. Some suffer with brain inflammation, or encephalitis; or inflammation of membranes around the brain and spinal cord, called meningitis. Some central nervous system damage may be permanent, Meece said, and about 1 in 10 with severe illness affecting the central nervous system die.
Diagnosis
If you think you’ve had a mosquito bite that’s led to symptoms, especially of neurological illness, Meece recommends you see your health care provider who can order tests to confirm an infection.
“The hard thing about these kinds of symptoms is they can be almost anything,” she said. “Rare tick-borne and mosquito-related diseases look the same. Because they’re rare it takes time to figure out what disease it may be and there aren’t commercial tests available yet so we rely on public health for diagnosis.”
If you don’t feel well and are not getting better see your health care provider. “Be your own health care advocate,” Meece said, “because it’s a rare disease in humans.”
Treatment
There are no vaccines or antiviral treatments. Over-the-counter pain relievers, though, can help reduce fever and relieve some symptoms, Meece said. When illness is severe, patients often need to be hospitalized for care that includes IV fluids and pain medication.
Prevention is key
So, an ounce of prevention is definitely worth a pound of cure. It’s simple. Prevent mosquitoes from biting. Meece offers this advice:
- Use EPA-registered repellents that are safe and effective. Spray repellent onto your hands and then apply, especially to your face, and always follow product label instructions. Reapply as needed. If you use sunscreen, apply it before using the repellent.
- Wear light-colored long-sleeved shirts and long pants.
- Treat your clothing and gear, including your tent, with permethrin or buy them pretreated. Permethrin is an insecticide that kills or repels mosquitoes.
- Control mosquitoes in your environment by reducing breeding habitats.
-
- Window and door screens provide indoor protection.
- Because mosquitos find stagnant pools of water to lay eggs, empty, turn over, cover or throw out “container breeding” items on your property that hold water, like tires or buckets.
- Safely handle dead birds. Use a shovel or gloves and double plastic bags to place them in the garbage.
- Report seeing dead birds, especially corvids – crows, blue jays, magpies and ravens – since they are susceptible and good sentinels for West Nile. Other birds may get West Nile and not die. Call the Dead Bird Reporting Hotline, Wisconsin Department of Health Services, open May 1 to Oct. 31, to report a sick or dead bird. From a Wisconsin area code, call 800-433-1610. Call 608-837-2727 from a non-Wisconsin area code. Also, Hotline staff will answer your West Nile questions.