In early July, CDC reported 48 human West Nile virus cases through June 30, 2026, and 38 of them were neuroinvasive, the serious form that reaches the brain or spinal cord. A typical year has about 10 cases by the end of June. Medical Daily noted that the last season to start this early was 2004, which ended with more than 2,500 cases and 100 deaths. Arizona's Maricopa County was hit first and hardest, with 29 cases and five deaths by July 1.
That pace produced a summer of worst-in-decades headlines, and our June post covered the early mosquito detections behind them. With the season winding down, CDC's own weekly tables tell a more complicated story, and the gap between the numbers is worth understanding before you decide how worried to be.
What CDC's weekly tables show now
CDC publishes West Nile counts through two systems. ArboNET, run with state health departments, produced the early-summer figures. The National Notifiable Diseases Surveillance System (NNDSS) publishes a weekly table of the cases states have formally reported. In the NNDSS table for the week ending September 12, 2026, the year-to-date count of West Nile disease in U.S. residents was 317. At the same point in 2025 it was 1,891.
Several of last year's hot spots are far quieter. Colorado had 14 reported cases against 264 at the same point in 2025, Minnesota 4 against 142, and Illinois 5 against 122. California, at 66, was close to last year's 74, while Texas, at 48, was well below its 112.
Why the numbers don't line up
The weekly table counts only what each state has submitted, and CDC labels the 2025 and 2026 figures provisional. Arizona's row lists no 2026 cases submitted at all, even though Maricopa County alone had reported 29 cases by July 1, so the national total is missing at least one of the year's worst-hit areas. Delayed reports and reclassified cases keep moving these numbers for months.
Both things can be true at once: 2026 started unusually early, and the cases states had formally reported by mid-September were well below last year's. For your household, local activity matters more than either national figure.
Local reports still show real risk
New Jersey shows why. Its health department's report for September 27 to October 3 counted 30 human cases in 14 counties so far this year, including two deaths, plus five blood donors whose donations tested positive. Cases in recent weeks were higher than average, and 1,250 mosquito pools had tested positive, above historical trends. The state was still adding cases in October.
What to do before the first hard frost
The Culex mosquitoes that carry West Nile breed in standing water and keep biting into the fall. Empty or turn over anything that holds water at least once a week, clear clogged gutters, and change birdbath water. Use an EPA-registered repellent such as DEET or picaridin when you are outside at dawn and dusk, and repair torn window screens.
Older adults and people with weakened immune systems face the highest risk of severe illness, so they have the most reason to avoid bites. There is no licensed vaccine or specific treatment for West Nile in people.
The bottom line
A fast start does not guarantee a record year, and a quiet national table does not mean your county is quiet. Check your state health department's weekly arbovirus report through October, keep up the standing-water routine until a hard frost, and wear repellent at dusk. Our mosquito pages explain which species carry West Nile and how to cut breeding around your home.
Sources: Drug Topics, CDC ArboNET data through June 30, 2026, and Maricopa County figures (July 8, 2026); Medical Daily (July 2026); CDC National Notifiable Diseases Surveillance System, weekly table for the week ending September 12, 2026; New Jersey Department of Health vector-borne disease report, September 27 to October 3, 2026. The Wire summarizes and contextualizes primary reporting; we do not republish.