West Nile virus kills 12 in the Netherlands, which had recorded only 8 cases before this year

An outbreak of West Nile virus in the Netherlands has claimed 12 lives, with confirmed infections reaching 77.

Here's what to know

RIVM, the Dutch institute for public health and the environment, recorded one additional human infection in its weekly update, according to NL Times.

The case was reported in Zuid-Holland, which accounts for 45 confirmed infections — more than half of the national total.

Utrecht has recorded 14 infections, making it the province with the second-highest count. Noord-Holland and Noord-Brabant have reported seven infections each, while Gelderland and Overijssel have each recorded two infections.

More background

RIVM's monitoring covers infections in birds, horses, and people. Birds are part of the virus's transmission cycle, and mosquito bites can carry the infection to humans.

West Nile can produce serious complications or flu-like symptoms, but most infected people have mild symptoms or none at all.

Brain inflammation, inflammation of the membranes surrounding the brain, and a polio-like illness can occur in rare West Nile cases, according to NL Times.

West Nile infection is more likely to be fatal in people who have underlying health problems.

What's being done?

RIVM is monitoring the outbreak through weekly updates on human infections, deaths, and positive animal tests. Its report added two deaths, bringing the national total to 12.

The same update recorded positive tests in five additional birds and four additional horses, according to NL Times.

RIVM believes the outbreak's peak has passed, since mosquito season has ended.

Before the 2026 outbreak, the country's only detected human West Nile infections occurred in 2020, when eight cases were documented around Utrecht and Arnhem.

Where can I learn more?

West Nile infections and mosquito problems are affecting U.S. communities, too. 

• New York's West Nile case count has already surpassed its 2025 total.

• Massachusetts raised West Nile risk levels across 10 Berkshire County towns.

• In San Antonio, neighbors call a clogged stormwater basin a mosquito factory.

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