Blue crabs affected with shell disease displayed a wide array of pathologies in response to this very common affliction. Grossly, shell disease lesions most commonly presented as variably sized brown to black foci. Such lesions ranged from very small (1 mm 2 ) to locally extensive (up to 200 mm 2 in area). The larger of the melanized lesions sometimes appeared ulcerated. The most severe lesions observed (Pamlico River shell disease-PRSD) resulted in loss of up to 25% of the entire carapace. A diverse bacterial flora consisting of aeromonads, vibrios and five other genera were isolated as the predominant organisms from shell disease lesions. Fungi were rarely observed in larger lesions. Protozoa and algae were also rarely observed on the surface of some lesions. Histologically, lesions
ranged from mild erosion of the epicuticle and
outermost layers of the calcified endocuticle to
more extensive endocuticle erosion with accompa-
nying inflammation. In the most severe cases, there
was total loss of the endocuticle and epidermis,
with pseudomembrane formation, intense haemo-
cyte infiltration, and involvement of adjacent vis-
cera. There was no apparent relationship between
the size of gross lesions and their histological
severity (as defined by the extent of tissue damage),
suggesting that gross examination of shell disease
lesions is not a reliable method for assessing the
damage to affected blue crabs.
Blue crabs affected with shell disease displayed a wide array of pathologies in response to this very common affliction. Grossly, shell disease lesions most commonly presented as variably sized brown to black foci. Such lesions ranged from very small (1 mm 2 ) to locally extensive (up to 200 mm 2 in area). The larger of the melanized lesions sometimes appeared ulcerated. The most severe lesions observed (Pamlico River shell disease-PRSD) resulted in loss of up to 25% of the entire carapace. A diverse bacterial flora consisting of aeromonads, vibrios and five other genera were isolated as the predominant organisms from shell disease lesions. Fungi were rarely observed in larger lesions. Protozoa and algae were also rarely observed on the surface of some lesions. Histologically, lesions
ranged from mild erosion of the epicuticle and
outermost layers of the calcified endocuticle to
more extensive endocuticle erosion with accompa-
nying inflammation. In the most severe cases, there
was total loss of the endocuticle and epidermis,
with pseudomembrane formation, intense haemo-
cyte infiltration, and involvement of adjacent vis-
cera. There was no apparent relationship between
the size of gross lesions and their histological
severity (as defined by the extent of tissue damage),
suggesting that gross examination of shell disease
lesions is not a reliable method for assessing the
damage to affected blue crabs.
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