West Nile Virus
Overview
Causes
The infection is caused by a virus. The virus is spread to humans from the bite of an infected mosquito. Rarely it has spread from an infected blood transfusion, organ transplant, and breastfeeding.
Risk Factors
Things that raise the risk of WNV are:
- Spending time outdoors—in areas with mosquitoes
- Not using insect repellent
- Mosquitoes in the home
- Certain gene defects—that may make some people get infected more easily
Severe WNV is more common in men and people over 50 years old. Other things that raise the risk of severe WNV are:
- A weak immune system
- High blood pressure
- Diabetes
- Cancer
- Kidney disease
- Alcohol abuse disorder
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SymptomsandDiagnosis
Symptoms
Most people with WNV have no symptoms. Others develop flu-like symptoms such as:
- Fever and chills
- Headache
- Muscle pain
- Nausea and vomiting
- Diarrhea
- Rash
- Swollen lymph nodes
- Eye inflammation— conjunctivitis
Symptoms can last from a few days to several weeks.
A small number of people with WNV develop serious symptoms, such as:
- Headache and sensitivity to light
- High fever
- Stiff neck
- Confusion
- Lack of responsiveness or coma
- Uncontrolled body movements
- Muscle weakness, or not being able to move
Treatments
Treatment
There is no specific treatment for WNV. Treatment depends on how severe the disease is. The goal is to manage symptoms and problems. In severe cases, hospital care is needed.
Depending on the symptoms, options may be:
- Pain medicines
- Medicine to ease nausea and vomiting
- Fluids by mouth or IV—to treat dehydration
Treatment for severe symptoms may include:
- Mechanical ventilation
- Medicine to control seizures
- Medicine to decrease brain swelling
This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.
Edits to original content made by Denver Health.
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