DAO 81:219-229 (2008)  -  DOI: https://doi.org/10.3354/dao01948

Environmental distribution and persistence of Quahog Parasite Unknown (QPX)

Rebecca J. Gast1,*, Dawn M. Moran1, Corinne Audemard2, M. Maille Lyons3, Jackie DeFavari4, Kimberly S. Reece2, Dale Leavitt5, Roxanna Smolowitz4

1Woods Hole Oceanographic Institution, and 4Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA
2Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, Virginia 23062, USA
3Department of Marine Sciences, University of Connecticut, Groton, Connecticut 06340, USA
5Roger Williams University, Bristol, Rhode Island 02630, USA

ABSTRACT: Quahog Parasite Unknown (QPX) is the cause of mass mortality events of hard clams Mercenaria mercenaria from Virginia, USA, to New Brunswick, Canada. Aquaculture areas in Massachusetts, USA, have been particularly hard hit. The parasite has been shown to be a directly infective organism, but it is unclear whether it could exist or persist outside of its clam host. We used molecular methods to examine water, sediment, seaweeds, seagrass and various invertebrates for the presence of QPX. Sites in Virginia and Massachusetts were selected based upon the incidence of QPX-induced clam die-offs, and they were monitored seasonally. QPX was detectable in almost all of our different sample types from Massachusetts, indicating that the parasite was widely distributed in the environment. Significantly more samples from Massachusetts were positive than from Virginia, and there was a seasonal pattern to the types of samples positive from Massachusetts. The data suggest that, although it may be difficult to completely eradicate QPX from the environment, it may be possible to keep the incidence of disease under control through good plot husbandry and the removal of infected and dying clams.


KEY WORDS: Quahog Parasite Unknown · QPX · Environmental detection · Remediation


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Cite this article as: Gast RJ, Moran DM, Audemard C, Lyons MM and others (2008) Environmental distribution and persistence of Quahog Parasite Unknown (QPX). Dis Aquat Org 81:219-229. https://doi.org/10.3354/dao01948

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