Perkinsus marinus

Identification

Due to a long dormant phase, identification can be difficult but is possible using molecular analysis methods. When it infects oysters' blood cells, it can be seen in reduced growth and overall health.

Life Cycle

Single host, facultative parasite of oysters, especially the species Crassostrea virginica

P. marinus is free-living as a motile zoospore or non-motile trophozoite. It infects host oysters when consumed during filter-feeding. Phagocytic hemocytes take in trophozoites after recognizing a surface protein. Hemocytes migrate through the host and lead to infection throughout all tissues, which eventually results in death.

Host Information

Infection with P. marinus results in "dermo" disease in oysters. The transmission rate is highest when host mortality is also at its highest, usually in late summer at high infection intensity, and it has caused mass mortalities of C. virginica. Other species, like Mercenaria mercenaria, Crassostrea gigas and Crassostrea ariakensis, are more resistant to the disease.

Distribution

P. marinus is found along the East coast of the US, along the Gulf of Mexico coast, and in the Paraíba river in Brazil. Accidental introductions and increasing sea-surface temperatures have expanded its range in recent years. It survives and transmits best in waters over 20 degrees Celsius.

https://www.dfo-mpo.gc.ca/science/aah-saa/diseases-maladies/pmdoy-eng.html