Review on the Protozoan Parasite Perkinsus olseni (Lester and Davis 1981) Infection in Asian Waters

Perkinsosis is a shellfish disease caused by protozoan parasite belonging to the genus Perkinsus. Perkinsosis has been reported in some commercially important shellfishes including oysters, clam, abalone and scallop. Heavy infection with Perkinsus often results in tissue inflammation and mass mortalities. Perkinsus trophozoites are commonly occurring in gills, digestive glands, mantle and gonadal connective tissues. Perkinsus is also believed to be responsible for the decline in clam landings for the past decades in Korea. Perkinsus infection was also reported in China, Japan and Thailand, from Japanese short-necked clam and the undulated clam. Microscopic features of different life stages and DNA sequences from the non-transcribed spacer and internal transcribed spacer indicated that Perkinsus sp. discovered in Asian waters are P. olseni. Field survey results suggested that reduced growth and reproduction as well as mass mortalities observed in some major clam beds in Korea was in part, associated with high level of Perkinsus infection.Nagasaki University Major Research Project: Restoration of Marine Environment and Resources in East Asi