© 2003 Alistair Dove, Cornell University You can contact one of the offices listed below What is QPX? for additional information on QPX disease and The acronym stands for Quahog Parasite the status of the hard clam fishery in New York. Unknown. It is a single-celled microscopic parasite that causes a disease in hard clams Debra Barnes known as ‘QPX disease’. QPX is understood New York State Department of to be a species-specific parasite of the north- Environmental Conservation ern hard clam or quahog (Mercenaria Bureau of Marine Resources mercenaria), only. QPX is not a threat to 631.444.0483 human health. There are no known cases of the QPX parasite infecting other marine Bassem Allam, Ph.D. animals or humans. Marine Disease Pathology & Research Consortium Microscopic view of QPX parasites in hard Stony Brook University Where does QPX come clam tissue sample. 631.632.8745 from? tive parasite, the theory suggests that the Ken Gall The QPX parasite is one member of a large QPX organism is routinely present in New York Sea Grant group of organisms that are common in the sediment and waters throughout the range, Stony Brook University water column and sediments in the marine and it doesn’t cause disease until there is 631.632.8730 environment. They are unique because they extraneous environmental stress, or some possess characteristics of both a fungus and other factor that makes clams less able to an animal. While the QPX parasite infects fight infection. Another theory is that QPX The Marine Disease Pathology & Research hard clams specifically, other members of this is an obligate parasite. Obligate parasites Consortium is a collaboration between the New group have been found in diseased inverte- must live in a host at some stage in order to York State Department of Environmental brates including abalone, sea hare (nudi- complete their life cycle. As an obligate Conservation, Stony Brook University, Cornell branch), octopus and squid. Another relative parasite, the theory is that QPX is a recently University College of Veterinary Medicine, of QPX is believed to be the cause of wasting introduced disease organism that is spread- South Hampton College, Long Island Univer- disease in eelgrass. ing when infected clams are transferred sity, and New York Sea Grant. from one location to another. Neither How does QPX infect hard theory has been proven at this time. Labo- © 2003 New York Sea Grant ratory experiments have demonstrated that clams? QPX organisms from a diseased clam can infect adjacent clams, but exactly how this New York Sea Grant is funded by the U.S. Department of Commerce The origin of QPX disease is currently the National Oceanic and Atmospheric Administration and the State of New subject of scientific debate. The life cycle of process occurs is still not understood. York. It is a joint program of Cornell University and SUNY. the QPX organism and the way it causes Situations where clam density is very high disease in clams are not well understood. are thought to enable the QPX organism to One theory suggests that QPX is a facultative transmit more easily. Scientific research is parasite. Facultative parasites are organisms needed to understand the QPX parasite, it’s that may either lead an independent exist- life cycle, strain variations, and how it is ence, or live as a parasite (but do not need a transmitted.

New York host to complete its life cycle). As a faculta-

July 2003 Where has QPX disease been What are the signs of QPX adequately pump and cleanse themselves for a minimum of 21 days before they are released found? disease? into the market. Hard clams harvested under Although the first reports of QPX-like organ- Several signs have been reported in hard the Raritan Bay Shellfish Transplant Program isms were in dead or dying clams in New clams infected with the QPX organism. Prior have increased since the program began in Brunswick, Canada in 1959 and in Barnegat to 1995, clam death was the only reported 1987, and as many a half of the hard clams Bay, New Jersey in 1976, it wasn’t until the gross sign of the disease. Decreased new shell that were marketed in 2001, came from this 1990s that QPX disease began to be more growth, swollen and discolored mantles, and program. National Marine Fisheries Service widely associated with clam die-offs in the chipping shell edges were reported in the statistics indicate that the total dockside value Northeast and Mid-Atlantic. A QPX-like 1995 outbreaks in Provincetown and (amount of money paid to baymen) for hard organism was identified in diseased clams in Duxbury. The QPX parasite was found most clams harvested in New York was approxi- the Mitchell River in Chatham, MA in 1992, frequently in the mantle and gills of clams. mately $13.5 million in 2001. The dockside when high clam mortality was observed for a Clams usually show an intense inflammatory value of the clam resource directly affected by period of more than 8 months. A significant response to the parasite. Parasite infection the QPX disease outbreak in 2002 is estimated the center of the most productive part of the die-off associated with a high prevalence of was found throughout the internal organs of to be between $4-$5 million. fishing ground. The New York State Depart- the QPX organism was documented during infected hard clams in the 2002 outbreak in ment of Environmental Conservation has summer and fall of 1995 in both farm-raised New York, and the previously reported signs What is being done about since announced its decision to suspend the and wild hard clam populations in Duxbury associated with the mantle and shell were not Raritan Bay Shellfish Transplant program for and Provincetown, MA. Hard clams being common. QPX in New York? 2003, based on the results of the survey. The farmed in the Watchapreague, VA area on the The New York State Department of Environ- agency will evaluate the status of clam popu- ocean side of the eastern shore were diag- Why are we concerned mental Conservation collected samples for lations in the marine district, and continue to nosed with QPX in 1996, but there were no analysis after receiving reports of dead and monitor the Raritan Bay clam population for other clam mortalities associated with QPX in about QPX in New York? dying clams in the Staten Island area in QPX prevalence in cooperation with the VA until 2001. QPX was also discovered in It is not known with certainty whether or not August of 2002. The transplant program was Marine Disease Pathology and Research Pleasant Bay (Orleans, MA) and Barnstable QPX disease has occurred in New York’s hard suspended immediately after the presence of Consortium. Harbor (Barnstable, MA) on Cape Cod in clams prior to 2002. However, large numbers QPX organism was confirmed in infected hard Adapted from Massachusetts Division of winter and spring of 2001. The QPX organ- of dead or dying clams were reported in clams, in order to prevent possible transmis- Marine Fisheries and the South Eastern ism was found in a population of hard clams Raritan Bay off the coast of Staten Island in sion to wild clams in the Peconic Bay and Massachusetts Aquaculture Center, January, from Raritan Bay near Staten Island, New 2002, and the QPX organism was identified other receiving waters of the state. New York 2002. York in summer 2002; these clams were in these clams. A dense population of hard State Department of Environmental Conserva- being harvested as part of a controlled trans- clams has been harvested from this area since tion will be collecting samples from various Published through a grant from Stony Brook plant program. 1987 under the Raritan Bay Shellfish Trans- wild populations of hard clams in Peconic Bay University Marine Sciences Research Center. plant Program supervised by the New York to determine possible background levels of State Department of Environmental Conserva- QPX. A major survey of the Raritan Bay tion. This transplant program allows licensed population was undertaken as a collaboration baymen to harvest clams from uncertified between the New York State Department of waters under state supervision. Shellfish Environmental Conservation and the Marine transplanting is normally undertaken on a Disease Pathology and Research Consortium seasonal basis from April through October, at Stony Brook University. An unacceptable when water temperatures are high enough to high level of QPX was found during the © 2003 New York State Department of Environmental Conservation allow the shellfish to remain active and survey, and the disease was most prevalent in