Decontamination of Bonamia exitiosa

Mollusc aquaculture worldwide has suffered significant losses from disease caused by haplosporidian parasites. Bonamia exitiosa Hine, Cochennac & Berthe, 2001 has caused significant epizootics in oyster populations in New Zealand, America and Australia and threatens oyster industry expansion. Decontamination of equipment is an important management tool to limit spread of infection. There are no decontaminants with a regulatory authority for controlling B. exitiosa and no efficacy data are available. We assessed the efficacy of three disinfectants permitted by the Australian Pesticides and Veterinary Medicines Authority for decontaminating oyster pathogens against B. exitiosa. Purified B. exitiosa cells from infected Ostrea angasi Sowerby, 1871 were exposed to a quaternary ammonium compound (QAC), an iodine or chlorine based disinfectant for 1 min, 5 min or 10 min. After disinfectant exposure cell viability was determined using trypan blue staining and light microscopy. 40,000 ppm chlorine for 10 min and 2000 ppm iodine for 1 min provided 100% efficacy against B. exitiosa. QAC did not effectively decontaminate B. exitiosa, but QAC can be used for cleaning before decontamination. Understanding how to decontaminate B. exitiosa will aid development of management strategies for B. exitiosa in industry and laboratories.