A histopathology survey of California oysters

摘要

Pathogen surveys form an essential component of effective aquatic animal disease surveillance programs. We report the results of a histological examination of farmed (Crassostrea gigas, C. sikamea, C. virginica, Ostrea edulis) and wild Olympia (O. lurida) oysters collected from locations throughout the state of California during 2004-2005. Most of the symbionts encountered among 1676 oysters examined are commonly observed in oyster populations worldwide and are usually of negligible or minor significance as pathogens. These include ciliates, copepods, cestode larvae, gregarine protozoa, and Rickettsiales-like prokaryotes. Conditions or agents more commonly associated with disease include the protozoan Bonamia sp. in O. edulis and disseminated neoplasia in O. lurida. No organisms potentially pathogenic to humans were identified. Farmed and wild oyster populations in California generally appeared healthy in accordance with a lack of reports of significant mortality events with the exception of summer mortality of juvenile C. gigas in Tomales Bay which is associated with herpesvirus infection.