Ok......
Dr. Sheppard has a few concerns about posting here on the forum after reading some of the comments, but has agreed to allow me to post her thoughts on the matter.
If we can have this discussion move forward in a civil manner, and work towards a common goal, then I think Dr. Sheppard and others will be more willing to participate here with us all. So here are her comments:
Dr. Sheppard Wrote:
They are correct that animals dying of something infectious, even if they are imported, is not a general cause for concern and does reflect stress (some of which is avoidable with expert husbandry). It would generally just make this a finding for us veterinary pathologists to like having a quick reference paper on so we knew quickly what it was and could move on to other work that day. That was the original reason for writing this up. The number of organisms and amount of tissue damage are absolutely spectacular and the finding helps to explain the mortality observed by hobbyists. Even heavily infected animals with severe tissue damage to their visceral mass structures have extended mantles and look fantastic until a day or two before becoming completely moribund and dying. This is a frequent pattern in chronic infections of pathogens, such as Perkinsus, which are highly adapted to their hosts. It is a solid practical strategy to avoid killing one's host.
Unfortunately, the thing that makes this finding the focus of wider interest is that this is a pathogen causing financial issues for shellfish industries in other parts of the world in a variety of shellfish hosts such as abalone in South Australia, cockles in New Zealand, etc.. That means that it has the potential (albeit unproven since it is not in US waters- knock on wood) to cause damage to our domestic ecosystems and associated oyster industries. For that reason, finding it meant that it had to be reported to the USDA and international authorities by the editor who is involved in policy regarding the oyster industry and international trade of shellfish. His concern reflects his extensive expertise in this organism and his concern for the people who could be affected.
Our domestic shellfish industries, while not typically interested in ornamental clams or their husbandry-associated diseases, already face economic hardship from the North American form of this pathogen called Perkinsus marinus which causes heavy losses during harvesting and hot weather. Their representatives are concerned by the possibility that the Indo-Pacific form of the pathogen, P. olseni, has a potential source of entry in the form of ornamental clams. As you know, ornamental species are not subject to the testing etc experienced by the heavily regulated shellfish industries in our country.
Although hobbyists will point out that they discard their tank water down a drain leading to a water sanitation system of some type with virtually no exceptions, the presence of exotic species of animals and plants in various habitats including the Everglades and domestic waters is well-documented and solidly linked to inappropriate releases by the public.
The EU, for example, can request restrictions on export of live agricultural products citing concerns over the pathogen status of the US. That means a loss of revenue. The shellfish industry, and possibly environmentalists, may request new restrictions for entry of animals with pathogens that endanger their industry and foreign trade. This is reflected in voluntary efforts spear-headed by a consortium of USDA and industry stakeholders in Florida to test for Perkinsus. Heavy infections of this pathogen have subsequently been found in many T. crocea tested from 2005 to the present even upon immediate arrival. Perkinsus, a single cell protozoa with some physical similarities to organisms such as intestinal coccidia and malaria, is a chronic pathogen which infects animals long-term with rapid increases in the associated morbidity and mortality when the host is stressed. This means that the hosts arrive infected regardless of the good intentions of the importers or the husbandry skills of the consumer. It is a pathogen causing disease and is not a component of normal flora. It is not a bacteria or fungus and is not found long-term in water lacking an appropriate host.
The effect of the pathogen on the ornamental clams, while important to people who sell, buy and enjoy beautiful tridacnid clams, is of absolutely no significance to the shellfish industry or our foreign trading partners. The issue is based completely on their role as hosts to a foreign pathogen which could impact our domestic shellfish industries and acceptance of our products by international trading partners that have stricter regulations. Vietnam's geographical proximity to the P. olseni-infected waters of China and the Gulf of Thailand makes the finding of P. olseni in shellfish living in Vietnamese waters less than surprising, although unfortunate as their T. crocea are genuinely beautiful.
The original set of T. crocea are designated as aquacultured, a designation devoid of political meaning by the author, due to their origin from facilities maintained by those regional industries although it is my understanding that the stocks are collected from the wild; their exposure to the infected waters of that region whether during time spent in the wild or a contained area is the key element. Any clams co-housed with an infected clam can become infected and the water will contain infectious forms- this is because every known life stage of P. olseni is infectious, it does not require intermediate hosts such as snails or fish to replicate, and it releases infectious forms into the water while alive from its damaged internal tissues and after dying.
Identifying a source of tridacnids from a geographical location that does not have endemic P. olseni (perhaps isolated islands?) would be a constructive focus for the ornamental industry and its supporters.
I encourage your participants to move past their initial frustrations to become aware of the core issues, help find alternatives, and seek to educate enthusiasts on safe disposal of water/carcasses. I can make recommendations with regard to hygiene and potential strategies for removal of the organism based on its biology if requested. I believe your industry leaders and the hobbyists can make a positive impact on future decisions if they move forward in these areas.
I appreciate your making the step to call me and I hope I can help you all find some good alternative sources.
Thanks again,
B
Ok...me again....Pretty deep stuff there, and honestly I feel that we need to work with some suppliers to gather specimen samples from many regions, to do more studies. Dr. Sheppard was willing to do the lab work to further the study. Seems like this nasty pathogen is region specific, so if we can prove that same species are not all infected, then we stand a chance to continue importation. I have discussed this with the good Doctor and we have a plan on how to handle water samples, tissue samples and specimens etc.....
Open for comment.
