Genome Sequencing takes aim at Dermo to protect the industry

March 12, 2026

Genome sequencing is homing in on Dermo, one of the emerging parasitic diseases endangering Atlantic Canada’s farmed and wild oyster industry.

“If nothing is done,” Dr. Attiq Rehman, Director of Biosciences at the Research and Productivity Council (RPC) in Fredericton, predicts, “Dermo could cause major losses for oyster farmers, wipe out wild oyster populations that keep coastal ecosystems healthy and permanently change where and how oysters can be grown in Atlantic Canada.”

Doing nothing is not an option for either Dr. Rehman or Dr. Tony Manning, RPC’s Senior Research Scientist, Aquatic Health, and their RCP team. Supported by Genome Atlantic’s Genomics Opportunity Review Program, they are carrying out a pilot study to sequence strains of Perkinsus marinus in Atlantic Canada, the parasite that causes Dermo. The pilot study is the first critical step to counter the latest threat to the oyster industry.

Like MSX, another parasitic disease nipping at the industry’s heels, Dermo poses no risk to food safety or human health, but it kills oysters. “Unlike MSX which appears to have some seasonal limits and may require an immediate host, Dermo spreads easily through water and directly from infected oysters to healthy ones,“ said Dr. Rehman. “ The parasite is released in feces and decaying tissue and taken up by other oysters during filter-feeding.” In oysters over a year old, Dermo can retard growth and produce 50-70 per cent mortality rates. In contrast, MSX infects oysters of all ages although usually they are older than two years, with mortality rates of up to 95 per cent. Crucially, however, Dermo is proving much harder to control.

First discovered in late 2024 in New Brunswick, Dermo reached Prince Edward Island in mid 2025, and it has now spread to waters throughout Atlantic Canada and Quebec.

“Sequencing the parasite’s genome is essentially like reading its instruction manual,” Dr. Rehman explained. “By decoding the genetic blueprint of multiple strains, we can learn more about how the parasite evolves, spreads, and why certain strains are more virulent or resilient.”

According to Dr. Rehman, the information is vital to design diagnostic tools for the disease, to improve tracking of Dermo outbreaks, and to enable selective oyster breeding programs to develop Dermo-resistant oysters. Also, the keys to develop targeted treatment and chemotherapeutic responses – particularly effective in controlled environments like hatcheries – lie in identifying the genes and proteins involved in host-parasite interactions.

“Ultimately,” he said, “these genomic insights [will] support the production of oysters that remain disease-free and reach market size, helping to ensure the recovery of wild populations, preserving critical ecosystem services and securing a sustainable and profitable shellfish industry.”

For this study, the team is using Oxford Nanopore long-read sequencing. It produces “extremely long DNA reads,” said Dr. Rehman, giving significantly more detailed information about the parasite’s genetic code. “It’s like reading whole chapters of a book instead of just a few words. Plus, it lets us do the sequencing faster and locally at RPC,” he said.

“By comparing strains from different places, we want to see if the parasite is the same everywhere, or if it changes, based on local conditions like water temperature and salinity,” said Dr. Rehman. The team also expects to learn about the relative harmfulness and adaptability of the different strains to gain insight into the way climate and location affect the spread of the disease. Samples of infected oysters for the study are expected to come from all four Atlantic Provinces.

The gathered genetic data will help regulators “monitor outbreaks, set movement controls and strengthen early-warn systems for Dermo outbreaks,” said Dr. Rehman, while giving oyster farmers, the ability “to make smarter choices about where to get seed oysters and when to harvest to reduce losses.”

'RPC is “uniquely positioned to lead this work.” Atlantic Canada’s oyster industry is relying on it.'

- Dr. Attiq Rehman

Essentially, he said, “understanding the parasite’s genetic code makes it easier to track, predict and control outbreaks before they cause serious problems.”

All data from this project will be made public using the open-science model in a move to accelerate scientific collaboration to control Dermo. “Open science,” he said, “turns this project into a shared global effort, helping speed up solutions that protect Atlantic Canada’s oyster industry. In short, open data makes teamwork easier and drives innovation much faster.”

RPC, with its mission to support industry with innovative scientific solutions, has a history of helping aquaculture. It began a Fish Health diagnostic service in 1984 and helped the Atlantic salmon industry by first identifying the infectious salmon anemia virus in the 1990s and then developed a surveillance program that helped save the industry from significant losses. “Now oysters need the same proactive approach,” said Dr. Rehman.

With its ISO-17025 accredited lab, strong partnerships and track record in disease surveillance, he said RPC is “uniquely positioned to lead this work.” Atlantic Canada’s oyster industry is relying on it.

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