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Identification of the Causal Agent of Malpeque Disease in Oysters



The oyster industry has been plagued on several occasions by a highly infectious malady named Malpeque disease. Initially, the disease appeared in 1915 in Malpeque Bay, PEI, and new epizootics in the 1950's and 60's greatly affected the industry, with losses of up to 90% of affected stocks. Losses from the disease continued throughout the Gulf of St-Lawrence with disease tolerance developing over extended periods of time followed by recovery of most stocks. In 2007, new outbreaks of Malpeque disease were observed in the Bras D'Or Lakes and St Ann's Harbour, Cape Breton. Malpeque disease is believed to be caused by a pathogen, although all attempts to identify the cause of this abnormal condition have been inconclusive. The disease is diagnosed on various gross and histological observations e.g. mantle regression, gaping, nodules in the mantle, accumulation of ceroid-containing cells, haemocyte infiltration and focal haemocyte accumulations.

We propose a two parts project leading to the development of molecular-based tools for the diagnosis of Malpeque disease. The first part of the project will be to confirm the presence of a pathogen in infected oyster tissues, by isolating small parts of its genetic material. Using these data, the second part of the project will be the development of a PCR-based test to determine the presence or absence of the pathogen from animal tissues.

Program Name

Aquaculture Collaborative Research and Development Program (ACRDP)


2008 - 2010


Atlantic: Gulf of Maine, Scotian Shelf

Principal Investigator(s)

Nellie Gagné

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