DAO 79:229-235 (2008)  -  DOI: https://doi.org/10.3354/dao01888

Perkinsus olseni detected in Vietnamese aquacultured reef clams Tridacna crocea imported to the USA, following a mortality event

Barbara J. Sheppard*, Ayanna Carla Phillips

Department of Infectious Diseases and Pathology, Box 110880, College of Veterinary Medicine, University of Florida, 2015 SW 16th Avenue, Gainesville, Florida 32611, USA

ABSTRACT: Morbidity and mortality were observed in a group of 30 reef clams Tridacna crocea that were imported to Florida, USA, from a Vietnamese culture facility and held in research facility aquaria. Clinical signs included an incompletely extended mantle, slow mantle responses to stimuli, and sloughing of byssal tissue beginning 2 to 5 d prior to death. Necropsy findings included emaciation, visceral mass edema, and rare multifocal 1 mm off-white to light-tan gill nodules. Histopathology revealed marked inflammation and necrosis within the visceral mass and gills, with interstitial edema and atrophy of glandular, gonadal, and muscular tissues. Inflamed tissues contained large numbers of 10 to 15 µm extracellular round organisms consistent with Perkinsus sp. trophozoites. The organisms often formed clusters of 1 to 4 cells and were surrounded by a 1 to 3 µm rim of eosinophilic material variably forming a radiating corona pattern and by 3 to 4 host hemocytes with dense round nuclei. Polymerase chain reaction assays indicated the presence of Perkinsus sp. DNA in these animals, and species-specific assays indicated the presence of P. olseni, and possibly other Perkinsus spp., but not P. marinus. Identification of Perkinsus spp. other than P. marinus in T. crocea imported from Vietnam confirms that importation of untested and unquarantined ornamental reef clams has possibly allowed incursion of P. olseni into the USA.


KEY WORDS: Perkinsus olseni · Tridacna crocea · Bivalve · Inflammation · Vietnam


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Cite this article as: Sheppard BJ, Phillips AC (2008) Perkinsus olseni detected in Vietnamese aquacultured reef clams Tridacna crocea imported to the USA, following a mortality event. Dis Aquat Org 79:229-235. https://doi.org/10.3354/dao01888

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