West Nile Virus and Mosquitoes: Separating Myth From Guidance
West Nile Virus and Mosquitoes: what people commonly get wrong, set against what published US guidance says.
Most people never feel ill, but a small share develop serious infections of the brain or spinal cord, and there is no vaccine or specific treatment.
Key takeaways
- No symptoms: about 8 in 10 infected people
- Fever and flu-like illness: about 1 in 5
- Most useful single change: Use an EPA-registered insect repellent on exposed skin, and apply sunscreen first if you use both.
- Commonest mistake: Leaving standing water in gutters, toys or plant saucers.
- See a doctor if any of the signs under "When to speak to a doctor" below apply to you.
What the guidance actually says
Here is what guidance actually publishes. The rest of the page is measured against it.
| Measure | Figure |
|---|---|
| No symptoms | about 8 in 10 infected people |
| Fever and flu-like illness | about 1 in 5 |
| Serious illness of the brain or spinal cord | about 1 in 150 |
| Highest risk of severe illness | people over 60 and those with certain medical conditions or weakened immune systems |
| Season | most cases occur from summer through fall |
| Vaccine for people | none available |
Where people go wrong
All of these come up regularly. All of them run against the published position.
- Leaving standing water in gutters, toys or plant saucers
- Using repellent on babies under 2 months, or oil of lemon eucalyptus on children under 3
- Relying on bug zappers or citronella candles alone
What to do instead
- Use an EPA-registered insect repellent on exposed skin, and apply sunscreen first if you use both
- Wear long sleeves and long pants when mosquitoes are active
- Empty, scrub or cover items that hold water, such as buckets, birdbaths, tires and planters, once a week
- Keep window and door screens in good repair and use air conditioning if you have it
The part that is genuinely uncertain
Guidance changes, and it changes because evidence does. The figures above reflect current US guidance from the bodies named at the foot of this page; where those bodies revise their position, theirs is the account to follow rather than this one.
Related topics
- What the Guidance Really Says About Malaria Prevention (Travel Health)
- What the Guidance Really Says About HIV (Sexual Health)
- Raw Milk: Sorting the Evidence From the Noise (Food Safety)
- Shingles Vaccination: What the Evidence Actually Says (Vaccinations)
Where to go next
- What West Nile Virus and Mosquitoes Is, and Why It Matters
- West Nile Virus and Mosquitoes: The Practical To-Do List
- West Nile Virus and Mosquitoes — the reference entry
- Infectious Diseases: The Complete Guide
- What the Guidance Really Says About Norovirus
- Strep Throat: What Published Guidance Supports
When to speak to a doctor
See your doctor if you develop fever, headache, body aches or a rash after mosquito bites, especially if you are over 60. Call 911 for a severe headache with a stiff neck, confusion, a seizure, sudden weakness, or trouble staying awake.
Where this comes from
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.
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