Canada’s Atlantic oyster industry may be threatened because of a disease called MSX that has infected many oyster farms in the region.

The federal Department of Fisheries and Oceans has confirmed four of nine samples from different Cape Breton Island aquaculture areas were detected and two lower levels of the disease were found on nearby Prince Edward Island.

Multinucleated Sphere X (MSX) is a disease caused by a microscopic single-celled parasite that is not harmful to humans but kills oysters, wreaking havoc on stocks. Local harvesters and restaurant owners continue to sell oysters but the department has banned them from being shipped from one production area to another prevent further infection.