The Protozoan Parasite <i>Perkinsus marinus</i> in Bivalve Mollusks From Mexico: A Review

ABSTRACT Unusual mortalities of the Eastern oyster Crassostrea virginica were reported in 1946 along bays of the Mississippi River, USA, and later attributed to the protozoan Perkinsus marinus . Initially described as Dermocystidium marinum , the parasite was reclassified and has since become one of the most extensively studied pathogens of bivalve mollusks. It is listed by the World Organization for Animal Health (WOAH) because of its significant impact. In Mexico, the parasite was first detected in C. virginica from Gulf of Mexico coastal lagoons during the 1950s. Despite decades of research, no international‐scale review of Mexican studies has been conducted. Twenty‐five articles and eight postgraduate theses were identified that have investigated P. marinus and presumptive P. marinus in Mexico. One of the most significant findings is its detection on the Pacific coast, linked to oyster translocations. The parasite has been reported in a wide diversity of bivalve mollusks belonging to the families Mytilidae, Ostreidae, Pinnidae, Veneridae, and possibly Arcidae. Only two field studies have associated the parasite with mortalities, and their results remain inconclusive. Current evidence suggests that strain variability, host susceptibility, and environmental conditions of Mexico may reduce the lethality of P. marinus . Further research is needed to clarify parasite virulence, host–parasite interactions, and environmental influences. Such studies would not only improve risk assessment in Mexico but also alert other regions to the potential biosecurity significance of P. marinus in diverse bivalves. In addition, Perkinsus chesapeaki and Perkinsus spp. have also been tentatively detected by molecular genetic analyses, which deserve research.