Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish

Haplosporidium costale (SSO) of Oysters

Category | Common Name | Scientific Name | Distribution | Host Species
Impact on Host | Diagnostic Technique | Methods of Control | References | Citation

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Category

Category 2 (In Canada and of Regional Concern)

Common, generally accepted names of the organism or disease agent

Seaside disease, Seaside organism, SSO, High salinity disease.

Scientific name or taxonomic affiliation

Haplosporidium costale, (=Minchinia costalis).

Geographic distribution

Long Island Sound, New York to Cape Charles, Virginia, USA, in high salinity waters (more than 25 ppt). Recently, plasmodia, but not spores, of H. costale were detected in low prevalence and intensity of infection in C. virginica from several locations in the Southern Gulf of St. Lawrence, Atlantic coast of Nova Scotia and Bras d'Or Lakes in Cape Breton, Nova Scotia, Canada.

Host species

Crassostrea virginica.

Impact on the host

Can cause a sharp (4-6 weeks) seasonal mortality in May and June in Virginia and Maryland which coincides with sporulation (Couch and Rosenfield 1968, Andrews and Castagna 1978, Andrews 1984). In Long Island Sound, rare cases (0.08%) of sporulation were detected in October to December (Sunila et al. 2002). The detection and confirmation of  plasmodia of H. costale using DNA probes in October in Virginia and Long Island Sound (Stokes and Burreson 2001, Sunila et al. 2002) is unprecedented and challenges historical criteria for the seasonality and epizootiology of this parasite. It is unclear whether this apparent change in seasonality is real or simply the result of improved diagnostic sensitivity (Burreson and Ford 2004). In situ hybridization assays indicate that co-infections with Haplosporidium nelsoni (MSX) occur.

Diagnostic techniques

Histology: Multinucleate plasmodia (typically less than 10 µm in diameter containing nuclei about 1.6 µm in diameter) and uninucleate spores containing bright red sporoplasm when stained by a modified Ziehl-Neelsen carbol fuschin technique. Synchronous sporulation of the parasite throughout the connective tissue of the digestive gland, mantle and gonads, but not in the epithelia of the digestive tubules. Plasmodia only easily detectable in March through June. Spores (about 3 µm in diameter) are usually found in moribund oysters (gapers). All stages of H. costale are approximately half as large as Haplosporidium nelsoni (MSX) and spores do not occur in the digestive tubule epithelia as for H. nelsoni. However, in the absence of spores, distinguishing between H. costale and H. nelsoni is nearly impossible using traditional histological examination. Haplosporidium costale cannot readily be detected between July and March.

Electron microscopy: During sporulation, plasmodia develop into sporocysts with spore walls forming around the nuclei. Spores (2.6 µm by 3.1 µm) are operculate and have a cap with an overhanging lid (Perkins 1969).

Immunological Assay: Polyclonal antibodies produced in rabbits against spores of H. costale recognized spores in paraffin sections of oyster tissue but not plasmodial stages of the parasite (Burreson 1988).

DNA Probes: A species-specific DNA probe from the small subunit ribosomal DNA sequence has been developed for H. costale (Ko et al. 1995). More recently, polymerase chain reaction (PCR) primers that target a region of the Small Sub Unit rRNA different from that of Ko et al (1995) have been identified and tested (Stokes and Burreson 2001). Multiplex polymerase chain reaction (MPCR which simultaneous tests for two or more pathogens in a single test reaction) was developed for H. costale, H. nelsoni, and Perkinsus marinus (Penna et al. 1999, 2001; Russell et al. 2000, 2004). PCR and in situ hybridization assays developed to specifically identify H. costale in conjunction with molecular tools previously developed for H. nelsoni have overcome the limitations of histological examination, which could not be used to differentiate between the plasmodial stages of these two parasites that overlap in geographic distribution (Stokes and Burreson 2001).

Methods of control

No known control methods. Losses can be minimized by harvesting oysters at 18-24 months of age. Salinities greater than 20 parts per thousand seem to favor M. costale (Andrews and Castagna 1978). The disease can be impeded by transplanting infected oysters to lower salinity waters (less than 25 ppt) (Ford and Tripp 1996). Particle filtration (1 µm filters) and UV irradiation of water entering hatcheries or nurseries should eliminate infective stages, as they do for H. nelsoni (ICES 2004). The mode of transmission is unknown.

References

Andrews, J.D. 1982. Epizootiology of late summer and fall infections of oysters by Haplosporidium nelsoni, and comparison to the annual life cycle of Haplosporidium costalis, a typical haplosporidian. Journal of Shellfish Research 2: 15-23.

Andrews, J.D. 1984. Epizootiology of diseases of oysters (Crassostrea virginica), and parasites of associated organisms in eastern North America. Helgoländer Meeresuntersuchungen 27: 149-166.

Andrews, J.D. and M. Castagna. 1978. Epizootiology of Minchinia costalis in susceptible oysters in seaside bays of Virginia's eastern shore, 1959-1976. Journal of Invertebrate Pathology 32: 124-138.

Andrews, J.D., J.L. Wood and H.D. Hoese. 1962. Oyster mortality studies in Virginia: III. Epizootiology of a disease caused by Haplosporidium costale, Wood and Andrews. Journal of Insect Pathology 4(3): 327-343.

Burreson, E.M. 1988. Use of immunoassays in haplosporidan life cycle studies. American Fisheries Society Special Publication 18: 298-303.

Burreson, E.M. and S. Ford. 2004. A review of recent information on the Haplosporidia, with a special reference to Haplosporidium nelsoni (MSX disease). Aquatic Living Resources 17: 499-517.

Couch, J.A. and A. Rosenfield. 1968. Epizootiology of Minchinia costalis and Minchinia nelsoni in oysters introduced into Chincoteague Bay, Virginica. Proceedings of the National Shellfisheries Association 58: 51-59.

Ford, S.E. and M.R. Tripp. 1996. Diseases and Defense Mechanisms. In: Kennedy, V.S., R.I.E. Newell, A.F. Eble (eds.) The Eastern Oyster Crassostrea virginica. Maryland Sea Grant College, College Park, Maryland. pp. 581-660.

ICES. 2004. Trends in important diseases affecting fish and molluscs in the ICES area 1998-2002. International Council for the Exploration of the Sea, ICES Cooperative Research Report No. 265. Copenhagen, Denmark. 26 pp. (Prepared and edited by the Working Group on Pathology and Diseases of Marine Organisms. For electronic publication see: http://www.ices.dk/pubs/crr/crr265/crr265.pdf).

Ko, Y.T., S.E. Ford and D. Fong. 1995. Characterization of the small subunit ribosomal RNA gene of the oyster parasite Haplosporidium costale. Molecular Marine Biology and Biotechnology 4: 236-240.

Mortensen, S., I. Arzul, L. Miossec, C. Paillard, S. Feist, G. Stentiford, T. Renault, D. Saulnier and A. Gregory. 2007. Molluscs and crustaceans, 5.3.21 Haplosporidiosis due to Haplosporidium costale. In: Raynard, R., T. Wahli, I. Vatsos, S. Mortensen (eds.) Review of disease interactions and pathogen exchange between farmed and wild finfish and shellfish in Europe. VESO on behalf of DIPNET, Oslo. pp. 408-409. (For electronic publication see www.dipnet.info under "Documents", subgroup "Reports and project deliverables").

Penna, S., R.A. French, J. Volk, J. Karolus, I. Sunila and R. Smolowitz. 1999. Diagnostic screening of oyster pathogens: preliminary field trials of multiplex PCR. Journal of Shellfish Research 18: 319-320. (Abstract).

Penna, M.-S., M. Khan and R.A. French. 2001. Development of a multiplex PCR for the detection of Haplosporidium nelsoni, Haplosporidium costale and Perkinsus marinus in the eastern oyster (Crassostrea virginica, Gmelin, 1971). Molecular and Cellular Probes 15: 385-390.

Perkins, F.O. 1969. Electron microscope studies of sporulation in the oyster pathogen, Minchinia costalis (Sporozoa: Haplosporida). The Journal of Parasitology 55: 897-920.

Russell, S., S. Penna and R. French. 2000. Comparative evaluation of the multiplex PCR with conventional detection methods for Haplosporidium nelsoni (MSX), Haplosporidium costale (SSO), and Perkinsus marinus (Dermo) in the eastern oyster, Crassostrea virginica. Journal of Shellfish Research 19: 580-581. (Abstract). This abstract was repeated verbatum in Journal of Shellfish Research 19: 648.

Russell, S., S. Frasca Jr, I. Sunila and R.A. French. 2004. Application of a multiplex PCR for the detection of protozoan pathogens of the eastern oyster Crassostrea virginica in field samples. Diseases of Aquatic Organisms 59: 85-91.

Stokes, N.A. and E.M. Burreson. 2001. Differential diagnosis of mixed Haplosporidium costale and Haplosporidium nelsoni infections in the eastern oyster, Crassostrea virginica, using DNA probes. Journal of Shellfish Research 20: 207-213.

Sunila, I., N.A. Stokes, R. Smolowitz, R.C. Karney and E.M. Burreson. 2002. Haplosporidium costale (seaside organism), a parasite of the eastern oyster, is present in Long Island Sound. Journal of Shellfish Research 21: 113-118.

Wood, J.L. and J.D. Andrews. 1962. Haplosporidium costale (Sporozoa) associated with a disease of Virginia oysters. Science (Washington D C) 136: 710-711.

 

Citation Information

Bower, S.M. (2007): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Haplosporidium costale (SSO) of Oysters.

URL: http://www.pac.dfo-mpo.gc.ca/science/species-especes/shellfish-coquillages/diseases-maladies/pages/hcoy-eng.htm

Date last revised:  October 2007
Comments to Susan Bower