Reported legionellosis surveillance for United States (USA) — ▲ Rising · 2025 — latest record 2026-10-25
As of 25 October 2026, the United States has reported 4,988 legionellosis cases in 2026, compiled from figures published by CDC NNDSS Weekly Notifiable Diseases (State-Level). The full year 2025 closed at 7,779 cases. The three-year baseline for United States is 2,092 cases a year. 2025 closed 272% above 3yr avg (WHO historical series), which is why the trend reads “Rising”.
Of the 7 countries reporting legionellosis to ENCLAI in 2026, United States accounts for 76.9% of reported cases and ranks 1 by case count.
ENCLAI has logged 1,948 surveillance records for legionellosis in United States in 2026, with the most detailed reporting in Aug 2026 (245 records). 147 of those arrived in the last 30 days; the case counts run to 2026-10-25. 1 distinct surveillance sources reported this pair in 2026.
Reporting authorities for these counts: CDC NNDSS Weekly Notifiable Diseases (State-Level)
One email a day: what changed in official disease reporting worldwide, with the source named for every number. Reported facts only — no forecasts and no interpretation.
| Year | Reported cases | Share of worldwide reports |
|---|---|---|
| 2023 | not reported | — |
| 2024 | incomplete year | — |
| 2025 | 7,779 | 82.0% |
| 2026 (year to date) | 4,988 | 76.9% |
Reporting bounds and case definitions vary; historical baselines are a separate comparison measure. Worldwide share compares this country's reported figure with the sum of all countries reporting legionellosis to ENCLAI for that year. "Incomplete year" means our sources cover less than ten months of that year, so no full-year figure is shown; "outbreak total to date" is a running total since an outbreak began, not a count for one year.
| Month | Records | Reporting sources |
|---|---|---|
| Jan 2026 | 154 | 1 |
| Feb 2026 | 155 | 1 |
| Mar 2026 | 216 | 1 |
| Apr 2026 | 179 | 1 |
| May 2026 | 229 | 1 |
| Jun 2026 | 186 | 1 |
| Jul 2026 | 192 | 1 |
| Aug 2026 | 245 | 1 |
| Sep 2026 | 196 | 1 |
| Oct 2026 | 196 | 1 |
A record is one dated surveillance publication or one row of an official table; a month with many records is a month with detailed reporting, not necessarily more cases. 147 records were logged in the last 30 days.
Areas within United States with the most legionellosis records this year:
| Area | Records |
|---|---|
| Arizona | 44 |
| Arkansas | 44 |
| California | 44 |
| Colorado | 44 |
| Florida | 44 |
Legionellosis in the US: 1,555 reported cases in the 90 days to 2 November, 590 of them in the 30 days to 2 November, 487 in the 30 days before that, 424 in the same 30 days a year earlier. Counts are as reported by the
Legionellosis in the US: 1,544 reported cases in the 90 days to 24 October, 599 of them in the 30 days to 24 October, 538 in the 30 days before that, 443 in the same 30 days a year earlier. Counts are as reported by the
| Country | 2026 cases | Trend |
|---|---|---|
| South Korea | 723 | ▲ Rising · 2025 |
| Australia | 646 | |
| New Zealand | 64 | ≈ Stable · 2025 |
| Lithuania | 42 | ▲ Rising · 2025 |
| Singapore | 19 |
| Disease | 2026 cases | Trend |
|---|---|---|
| Chlamydia infection | 620,278 | |
| Gonococcal infection | 202,064 | |
| Hepatitis C | 62,543 | ▲ Rising · 2025 |
| Campylobacteriosis | 38,167 | ▲ Rising · 2025 |
| Non-typhoidal salmonellosis | 26,618 |
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One email a day: what changed in official disease reporting worldwide, with the source named for every number. Reported facts only — no forecasts and no interpretation.
