The Centers for Disease Control and Prevention says a sample from Mohave County tested negative for brain-eating amoeba infection.
County officials sent in the specimens Tuesday out of concern that they could contain the free-living amoeba, known as Naegleria Fowleri. They did not say where it was found or why they suspected the amoeba to be present.
Infections are relatively uncommon in the U.S. with no more than five cases diagnosed from 2013 to 2022.
However, they are usually fatal.
One confirmed case was found in Lake Havasu in 2007. A Nevada teen died last year after he was exposed to the rare disease in the Kingman Wash on the Arizona side of Lake Mead.