MARION, Va. – Officials had to euthanize 40,000 trout in Virginia to prevent the spread of whirling disease, the Virginia Department of Wildlife Resources announced Thursday.

Whirling disease is caused by a microscopic parasite and leads to skeletal deformities in fish from the trout and salmon family, according to the DWR.

Humans cannot catch whirling disease, even if they consume infected fish.

The euthanized trout were at the Marion Fish Hatchery in southwest Virginia.

The fish account for about a 20% reduction in normal stocking levels for Southwest Virginia and a 5% reduction statewide, according to the DWR.

Officials noted that this reduction will result in lower trout numbers in certain areas, such as Dickenson, Buchanan, Wise, Lee, Scott, Russell, Washington, Smyth, Tazewell and Grayson counties.

The DWR is working to reallocate fish to mitigate the shortfalls.

The DWR said whirling disease is quite widespread and is found in more than 20 states.

The parasite and disease are native to Europe and were first detected in the U.S. in 1958.