With 87 cases of West Nile virus reported in 2025, South Dakota seems to have avoided the widespread outbreak experts anticipated earlier in the year.

In July, shortly after the first human case of 2025 was detected, the South Dakota Department of Health released a report projecting more than 130 cases for the year. That would have been the most in a single year for the state since 2018, when 169 cases were detected.

However, Joshua Clayton , South Dakota's state epidemiologist, told the Argus Leader that a combination of factors helps explain why there were fewer cases than expected.

"Weather patterns likely played a significant role, as stretches of hot, dry conditions can reduce mosquito survival and limit the opportunity for transmission," Clayton said. "City and county

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