Disease treatments for aquaculture are limited

When a fish farmer struggles with a disease or pathogen there is a very limited selection of approved treatment options available to fight it. This is even more apparent when a farm raises non-salmonid species as there are currently no approved medications and a limited number of vaccines available.

            Aquaculture in Canada is regulated by a myriad of agencies including numerous federal departments working in combination with various provincial and local authorities. Veterinary drug use is governed by two main divisions within Health Canada under four different Acts. Fish health and disease management lies with the Canadian Food Inspection Agency (CFIA) and the Department of Fisheries and Oceans (DFO) under the National Aquatic Animal Health Program (NAAHP) which was launched in 2005.

            Dr. Grace Karreman knows how to navigate this complicated regulatory system.  She

has spent 20 years working with the BC salmon farming industry as a clinical veterinarian and as a consultant on fish health projects to the private sector, provincial and federal governments. She also spent 3 years in Ottawa with the CFIA as the National Manager for Disease Control and Contingency Planning for aquatics. Since 2010 she has been the VP for Regulatory Affairs for Syndel Laboratories/Western Chemical Inc. 

                  In an interview with Aquaculture North America, she explained the difficulties in getting new treatments approved for use in aquaculture. “There are five main sections that each drug has to go through before it is approved for use with fish in Canada,” These sections include evaluating potential drugs for target animal efficacy, target animal safety, chemistry of manufacturing, human food safety and environmental safety.

            “The cost of developing products to these rigorous standards deters development of new treatments,” she added. On average it takes approximately twelve years for a drug to go through the approval process with some taking up to twenty years. In Canada, the most recent drug sanctioned for fish was Emamectin benzoate (Slice) which was approved in 2010. However, its use began as early as 2000 in Canada under the Emergency Drug Release process.  

            According to Dr. Karreman, Health Canada and the US Food and Drug Administration (FDA) have recently teamed together to work on joint approvals in order to expedite the process. The US Fish and Wildlife department established the Aquatic Animal Drug Approval Partnership Program (AADAP) in 2003 which was instrumental in collecting the experimental field data that led to the recent FDA approval of Chloramine-T (Halamid Aqua) as a therapeutic drug for fish. This was only the second waterborne drug approved by the FDA for use in fish within the last 30 years. The AADAP is currently collecting data on Eugenol (Aqui-S®20E), which is extracted from clove oil, and plan to add this as a second anesthetic option for fish. Currently, Isoeugenol is an approved anesthetic for fish in Europe but due to its potential carcinogenicity is not approved for use in North America.

            With the suite of drugs available to treat fish being so limited, it is vital that new products are developed and started through the approval process while maintaining rigorous safety standards. New products are required because as Dr.Karreman says “old treatments are not as effective – there are new emerging pathogens and diseases and general management requirements may be changing.  The reality is we are not going to get approvals very quickly.”

            One possible solution suggested by Dr. Karreman is to “incorporate new ways of discussing effective off-label usage of approved products.”

            With the focus on aquaculture to feed the growing population, a number of large pharmaceutical companies have shown interest in aquatic medicine which may lead to the development and approval of new drugs for use in aquaculture. However, the suite of drugs available will likely remain limited in North America due to the current low volume of usage and the cost getting drugs to the approval stage. This is especially true for non-salmonid aquaculture species and the inability to treat disease is a hindrance to the development of many new aquaculture species.

            Also complicating the situation is that new products in the pipeline may be closely guarded secrets known only to the pharmaceutical company.  Dr. Karreman predicts that, “in the future we are going to be focused on prevention of disease rather than treatments.”

            This will likely take many different forms such as new vaccines, strict water quality management, biosecurity products and genomics. Simply put, economics drives industry practises and it is cheaper to prevent disease than to treat it.

— Amanda Bibby