A comparison of diagnostic assays for detection of Perkinsus spp. in the softshell clam Mya arenaria

Perkinsus spp. infections are increasing in prevalence and intensity in sof tshell clams Mya arenaria, a commercially and ecologically important bivalv e of the Chesapeake Bay. In the present study, the gills, labial palps, rec tal tissue, and hemolymph from softshell clams were compared for their suit ability in thioglycolate diagnosis of Perkinsus spp. infection. Gill and pa lp tissues were more sensitive than either rectal tissue or hemolymph for d etecting light infections. Rectal tissues became effective measures of para site burdens as infections increased in intensity. Hemolymph samples were p ositive only in advanced infections. Further examination of paraffin-embedd ed tissue sections from lightly infected clams resulted in false negatives when compared with gill or palp thioglycolate assays. Hence, the use of bot h rectal and gill thioglycolate assays are recommended for routine diagnosi s of softshell clam Perkinsus spp. (C) 1999 Elsevier Science B.V. All right s reserved.