Submitted to: Journal of Shellfish Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/7/2002
Publication Date: 6/20/2003
Citation: DELANEY, M.A., BRADY, Y.J., WORLEY, S.D., HUELS, K.L. THE EFFECTIVENESS OF N-HALAMINE DISINFECTANT COMPOUNDS ON PERKINSUS MARINUS, A PARASITE OF THE EASTERN OYSTER CRASSOSTREA VIRGINICA. JOURNAL OF SHELLFISH RESEARCH. 2003. Interpretive Summary: The protozoan parasite commonly known as "Dermo" (Perkinsus marinus) has caused extensive mortality in Eastern oyster (Crassostrea virginica) populations, especially along both the Gulf and East Coast of the United States. This study evaluated the effectiveness of a new class of compounds, N-halamines, on both survival and reproduction of this parasite in salt water. The two N-halamine compounds used are commonly called MC (1-chloro-2,2,3,3-tetramethyl-4-imidazolidinone) and DC (1,3-dichloro-2,2,3,3-tetramethyl-4-imidazolidinone). Both compounds kept these parasites from reproducing or eliminated them in saltwater at levels that will not harm larval oysters. These compounds have the potential to be used in oyster hatcheries to disinfect the incoming water as well as preventing the spread of the parasite throughout the hatchery.
Technical Abstract: The pathogenic protozoan Perkinsus marinus (Mackin, Owen and Collier) is the cause of extensive mortalities in Eastern oyster, Crassostrea virginica, populations along both the Gulf and East Coasts of the United States. A series of experiments was undertaken to determine the effect of N-halamine disinfectants on this protozoan parasite. The organic N-halamine disinfectants, 1,3-dichloro-2,2,5,5-tetramethyl-4-imidazolidinone (DC) and 1-chloro-2,2,5,5-tetramethyl-4-imidazolidinone (MC), apparently damage the permeability of the parasites outer membrane and alter the osmoregulatory functions of the cell. Damaged parasites were unable to reproduce at concentrations as low as 5.0 mg/L total chlorine as DC at 8 hours exposure, or for the chemical MC at 5.0 mg/L at 12 hours exposure. The chemical compounds appear to lyse the larger meronts first, followed by lysis of the daughter spores. These studies strongly suggest that the chemical compounds DC and MC can be used to disinfect seawater allowing the production of specific pathogen-free stock in oyster hatcheries, as well as having the potential to prevent the spread of these parasites from contaminated oysters to uninfected oysters.