Scientific name or taxonomic affiliation Bonamia ostreae . Crassostrea gigas could not be experimentally infected. Actual pathology appears correlated to haemocyte destruction and diapedesis due to proliferation of B. ostreae .
Lesions occur in the connective tissues of the gills, mantle, and digestive gland.
Although some flat oysters die with light infections, others succumb to much heavier infections. Heavily infected oysters tend to be in poorer condition than uninfected oysters. Examine for 2-5 m spherical or ovoid organisms with a central nucleus within or outside the haemocytes. This method will also detect B. ostreae in hearts of oysters frozen and stored at -20 C for at least four years and held at 4 C for several hours before testing. Bonamia ostreae is distributed systemically in advanced infections.