Document Type

Article

Department/Program

Virginia Institute of Marine Science

Publication Date

1988

Journal

Journal of Shellfish Research

Volume

7

Issue

1

First Page

19

Last Page

25

Abstract

Diagnosis of the oyster pathogen Haplosporidium nelsoni (MSX) by paraffin histology is compared with a technique in which hemolymph drawn from the oyster adductor muscle sinus is examined for parasite plasmodia. Oysters from seed beds of the James River, Virginia imported to an MSX endemic area in May, 1986 were sampled monthly through December, 1986 and in February, 1987. A sample of 25 oysters was bled each month and then processed for sectioning. Of the 200 oysters sampled, 89 (44.5%) were diagnosed as infected using histology and 61 (30.5%) were diagnosed as infected using hemolymph examination. All the heavy and moderate infections diagnosed by paraffin histology were also diagnosed by hemolymph, but only 64.3% of the light infections and only 43.5% of the rare infections were diagnosed by hemolymph analysis. However, 92.3% of the undetected rare infections and 60.0% of the undetected light infections were localized in gills and plasmodia had not entered the circulatory system. The hemolymph technique, which takes about 4 h, detected 89.7% of the systemic infections diagnosed by paraffin histology.

Keywords

Haplosporidium nelsoni, MSX, oyster, diagnosis, techniques

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