Three additional waterways in the Canadian province of Prince Edward Island (PEI) have been quarantined due to the MSX oyster disease.

Boughton River, New London Bay/Stanley Bridge and Birds Island to Black Banks are the latest areas affected, joining Bedeque Bay, where the pathogen was first detected in early July, CBC reported.

The Canadian Food Inspection Agency (CFIA) is implementing controls to prevent further spread and minimize the impact on the local shellfish industry.

The CFIA announced and declared primary control zones in the affected areas; this means shellfish movement within or out of these zones now requires a CFIA permit to prevent the disease from spreading.

MSX, or multinuclear sphere X, which is caused by the parasite Haplosporidium nelsoni, can lead to an oyster bed mortality rate of up to 95%, though it poses no health risk to humans.

Fortunately, MSX does not impact mussels, which are the cornerstone of PEI's shellfish industry. According to Canada's Department of Fisheries and Oceans, PEI produces 80% of all mussels in Canada, generating an annual value of approximately CAD 30 million ($21.7m), as reported by Undercurrent News.

The oyster industry is nonetheless vital to PEI's economy and faces significant disruption. CFIA has committed to working around the clock to manage the low-risk movement of shellfish for human consumption or retail.

Provincial legislator Matt MacFarlane has urged PEI premier Dennis King's government to support research into MSX and provide financial aid to the affected industry.

Lawrence MacAulay, the Canadian member of Parliament who serves as the country's agriculture minister, also has expressed concern about the impact on PEI's oyster sector.

"The oyster industry is an integral and iconic part of the Island economy and countless Islanders depend on it to earn their living," his statement reads. 

"[DFO], the Province of PEI, and the [CFIA] are working together to co-ordinate the response to and management of this disease, along with industry, processors, and harvesters, and implement controls to prevent the movement and spread of the disease," he assured.