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West Nile virus surge in North America and Europe

Updated 6 times since CLSTR started tracking revisions of this situation.

What changed

2026-08-21 19:39 UTC → 2026-08-22 03:06 UTC · added removed

Public health agencies in the United States, Canada, and increasingly Europe, have reported a Europe continue to report significant surge in West Nile virus activity. In the United States, states such as Utah and California recorded increased positive mosquito pool counts and confirmed human cases. In Arizona, 143 cases and five deaths were reported, accounting for approximately half of the current U.S. cases. Recent data indicates the CDC has reported 222 human cases nationally, with concentrations in Arizona, Texas, and California. In New York, health officials have intensified surveillance. Arizona has recorded 143 cases and five deaths. In New York City, the number of West Nile-positive mosquito pools nearly doubled compared to the same period in 2024. The city has officials confirmed its the first human case of 2026, 2026 involving brain swelling. In swelling, while Los Angeles County, officials County reported the its first death of the 2026 season due to neurological complications, while South Carolina has declared an outbreak in the Pee Dee region. complications. In Canada, positive mosquito pools and bird infections were detected in Ontario. Additionally, Manitoba has reported four human cases, prompting the government leading to increase increased mosquito fogging in high-risk areas like such as West St. Paul. Global In Georgia, activity has also expanded been detected in Europe. In Italy, DeKalb and Chatham counties. European activity has expanded significantly. Italy remains heavily impacted, with the Istituto Superiore di Sanità has confirmed confirming 312 cases and 13 deaths since the start of the year, year. Notably, 156 of these cases presented in neuro-invasive forms. The virus is circulating in 16 regions, including Lombardy and Campania, where Caserta has emerged as a regional epicenter. Greece has emerged as the second most affected country in Europe, recording 157 cases and 13 deaths, with significant clusters identified high activity in Campania the Attica and Lombardy. Thessaly regions. In Sardinia, the province of Oristano Thessaly, two deaths have been documented among elderly individuals. Additionally, North Macedonia has reported 20 recorded 43 cases, including hospitalizations. with 40 laboratory-confirmed. In Georgia, activity has been detected Skopje, health officials identified the virus in multiple regions, including DeKalb County a dead crow and Chatham County, the latter of which confirmed Georgia’s second human case of 2026. are monitoring high-risk areas such as canals and septic tanks.

Versions

  1. 2026-08-22 03:06 UTC West Nile virus surge in North America and Europe
  2. 2026-08-21 19:39 UTC West Nile virus surge in North America and Europe
  3. 2026-08-20 21:48 UTC West Nile virus surge in North America
  4. 2026-08-18 23:47 UTC West Nile virus surge in North America
  5. 2026-08-18 15:04 UTC West Nile virus surge in North America
  6. 2026-08-15 22:02 UTC West Nile virus surge in North America
  7. 2026-08-09 13:01 UTC West Nile virus surge in North America

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