[REVISION HISTORY]

West Nile virus cases rise in Europe and US

Updated 18 times since CLSTR started tracking revisions of this situation.

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2026-08-04 12:29 UTC → 2026-08-04 15:17 UTC · added ~~removed~~

Mosquito surveillance in July confirmed a rapid expansion of West Nile virus across Europe and North America. In the Balkans, Macedonia reported two laboratory‑confirmed cases on July 4 and later confirmed ten infections with seven additional suspected cases, three of which are in critical condition. Italy’s Emilia‑Romagna region detected the virus in mosquitoes across six provinces, prompting a heightened alert, while the national report later recorded 84 human infections, 37 neuro‑invasive and two deaths, leading to stricter blood‑donor and organ‑transplant screening. Spain’s Andalusia confirmed virus‑positive Culex mosquitoes in Seville and Almería and issued alerts for multiple municipalities, including Coria del Río and Dos Hermanas, where a neuro‑invasive case was hospitalized. Greece logged its first 2026 case in early July and, by late July, reported 21 confirmed infections—most with neurological complications—triggering mosquito‑spraying campaigns in Glyfada, Orestiada and other districts. In the United States, the season proved the earliest and most severe since 2004, with 48 cases (38 neuro‑invasive) by end‑June, a surge in Arizona (32 cases, five deaths), new cases in California’s Los Angeles and Long Beach counties, severe cases in El Paso, and first human infections reported in Utah, Maryland and Salt Lake County. France confirmed its first locally acquired case in Pyrénées‑Orientales. The European Centre for Disease Prevention and Control recorded 81 locally acquired infections across the continent, the majority in Italy (46) and Greece (21). Researchers in the United States identified a rapid brain‑protective response to West Nile infection, underscoring the need for continued vector control, public‑health alerts and personal‑protection measures throughout the summer. By early August, Italy’s outbreak grew to 84 confirmed infections (including two deaths) with 37 neuro‑invasive cases, spanning eight regions; Lombardy reported the highest tally and virus‑positive mosquitoes were also found in Abruzzo.

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