DISEASE FILE · GRADE C: WHO/CDC, CHECKED 2026-09
West Nile: the red flags are neurological.
About 1 in 5 infected people get fever; about 1 in 150 get the dangerous form, which touches the brain and nerves. The signs to know are weakness, confusion and stiff neck.
PLATE 204
- Gloves first: never bare-hand a dead bird
- Bag, label, call: the surveillance chain starts here
Bird to mosquito to human
West Nile is a surveillance disease before it is a household disease. The chain is how health departments see it first.
Dead crows and jays often appear before human cases. Do not handle the bird; report it.
Culex breed in organic standing water and bite at dusk. That is the hour the chain reaches people.
People do not pass the virus on. About 1 in 150 infections become the neurological form.
Neurological red flags: emergency care
These mark neuroinvasive disease: the 1-in-150 form that hospitalizes.
Dead bird, or your own signs
Two different jobs: report what you see outside, and know which signs mean an emergency for you.
Leave it. Call local health or wildlife. The specimen is data; handling it is not your job.
Most West Nile is mild. Watch for weakness, confusion or a stiff neck over the next days.
That is emergency care. Those three are the 1-in-150 form.
THE QUESTION PEOPLE ACTUALLY TYPE
How serious is West Nile virus? Most infections are silent; about one in five cause fever, and about one in 150 cause neuroinvasive disease with weakness, confusion or stiff neck. Those flags mean emergency care.
CDC West Nile clinical summary, checked 2026-09
The numbers, in context
Every row sourced, every page dated.
| FACT | VALUE | SOURCE |
|---|---|---|
| Silent infections | About 80% of cases | CDC |
| Fever form | About 20% | CDC |
| Neuroinvasive form | About 1 in 150 | CDC |
| Vector | Culex, night biters, organic water | CDC |
| Treatment | Supportive only; no vaccine | CDC |
The 2024 US year, from the MMWR
West Nile is the domestic mosquito disease Americans actually get. It is not rare, and it is not mild when it reaches the brain.
| UNITED STATES, 2024 | COUNT |
|---|---|
| Human disease cases | 1,808 in 48 states and DC |
| Neuroinvasive | 1,347, 75% of cases |
| Deaths | 173, almost all neuroinvasive |
| Texas | 456 cases, a quarter of the national total |
CDC West Nile current-year maps and ArboNET tables
CDC MMWR, West Nile and other nationally notifiable arboviruses, United States 2024, checked 2026-09.