“White spot” disease, which is not harmful to humans but can kill of crawfish, has been confirmed in commercial ponds across southwest Louisiana and in the Atchafalaya Basin.

The disease was first detected last month at a crawfish farm near Arnaudville. More testing has confirmed the disease in 20 ponds in six parishes and in at least two samples of wild crawfish from the Basin, according to information from LSU Agricultural Center and the state Department of Agriculture and Forestry.

State Agriculture and Forestry Commissioner Bob Odom said the 20 positive results for commercial ponds were out of 29 tested, raising fears the disease is widespread.

Test results are pending on more than 70 other samples.

Crawfish season is drawing to a close and most farmers are draining their ponds.

Farmers who are restocking with “seed” crawfish in preparation for next year have been cautioned to carefully screen for white spot disease.

The disease is named for the spotty calcium deposits on the shells of infected shrimp, but crawfish with the disease dont always exhibit the spots.

Mark Shirley, southwest regional aquaculture specialist for the LSU Agricultural Center, said infected crawfish show signs of weakness and lethargy and may die.

The disease is believed to pose less of a threat to wild mudbugs than to crawfish raised in a pond.

Still unknown by researchers is how the disease spread to crawfish and what its effect on next years crop will be.