What is Whirling disease?

Whirling disease, Myxobolus cerbalis, is spread by microscopic spores found on the bottom of ponds, lakes, and rivers. It cannot be contracted by humans and fish carrying the spores are safe for consumption. In the life cycle of the disease, the spores are eaten by tubifex worms and develop into Triactinomyxons while inside the worms. The Triactinomyxons are released from the tubifex worms into the water, where they cling to the bodies of trout and burrow into the fish’s nervous system. Another metamorphosis within the fish results in a mature spore attacking the cartilage right behind the fish’s head. After several weeks, that results in spinal deformities and “whirling” motions by the fish. Black tails are additional evidence of a whirling-disease infection. Young rainbow and cutthroat trout, birth to nine months, are particularly vulnerable to whirling disease, although brown trout are relatively resistant to it. Brown trout are native to Europe and evolved with whirling disease.

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How can Whirling disease be prevented?

Anglers can take many steps to reduce its spread. Moving live infected fish, or parts of dead infected fish, is probably the biggest source of contamination. Anglers should never move live fish and always should dispose of fish entrails and skeletons properly in trash receptacles on land rather then throwing fish parts into the waters. Do not use kitchensink disposals to dispose of fish parts. Anglers also can thoroughly wash and dry their boots and other gear after fishing in public waters.

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