Transcript of USDA and DOI Avian Influenza Media Briefing August 14, 2006 - Washington, D.C.
MS. TERRI TEUBER: Good morning, everyone. This morning we'd like to provide an update on the Wild Bird Monitoring Program being conducted as an interagency project. With us today to offer some comments are Dr. Ron DeHaven, the administrator of the U.S. Department of Agriculture Animal and Plant Health Inspection Service; Dr. Sue Haseltine, associate director for Biology at the U.S. Department of the Interior, the U.S. Geological Survey; and Dr. Bill Raub, science advisor to the Secretary at the U.S. Department of Health and Human Services.
If you'd like spelling on any of those names, I'd be happy to assist you with those afterwards.
And with that, I'm going to turn it over to Dr. Ron DeHaven.
DR. RON DEHAVEN: Thank you, Terri. Routine surveillance testing has indicated the possible presence of H5N1 avian influenza subtypes in wild mute swans in the state of Michigan. Testing has ruled out the possibility that this is the highly pathogenic H5N1 virus that has spread through much of Asia, Europe and Africa. And I want to repeat that. This is not the highly pathogenic avian influenza virus that has spread through much of other parts of the world.
Further, we do not believe that this virus represents a risk to human health.
Genetic analysis of this particular virus indicates that it's similar to low pathogenic H5N1 avian influenza strains that have been found previously in North America. The fact that these swans showed no signs of sickness and there was no sign of disease in birds around them further suggests that we are dealing with a low pathogenic avian influenza virus.
Final confirmation of its pathogenicity will be made and reported when that testing is completed.
Let me explain that pathogenicity simply refers to the ability of a virus to produce disease. Thus, a low-pathogenic virus produces much less disease and mortality in birds that are affected than highly pathogenic viruses would.
Low pathogenic strains of the virus furthermore typically are of no human health concern, and this would include the low pathogenic H5N1 virus that has been found in wild birds previously in North America.
In fact there's another possibility with regard to this particular situation, and that is that these birds are not infected with an H5N1 virus at all; but instead they could be infected with two separate avian influenza viruses, one contributing the H5 component and the second virus contributing the N1 component. Further testing will determine whether or not that is the case.
Even if that is the case, this would not change our assessment relative to the low risk associated with this particular finding. These mute swans were resident wild birds, not migratory birds, and we have no reason to believe those birds that were positive had any connection with any commercial poultry. Again, these were wild birds, and we have no reason to believe that any commercial poultry have been exposed to these particular swans.
Confirmatory testing is continuing at the U.S. Department of Agriculture's National Veterinary Services Laboratories in Ames, Iowa, and this testing will determine the exact subtypes of the virus and confirm its pathogenicity, whether it's a highly pathogenic or a low pathogenic virus.
These results are expected within two weeks time, and we will make them public when they become available.
We are providing information about the sampling even though there is little reason for concern because of our commitment to transparency in the testing process.
I may also take this opportunity to give some background on avian influenza viruses in general. AI viruses are in the same family of viruses that produce flu in humans every year. AI viruses can infect chickens, turkeys, pheasants, quail, ducks, geese, guinea fowl, as well as a number of other birds including wild migratory fowl.
Worldwide there are literally hundreds of avian influenza viruses, each of which can produce varying degrees of illness in poultry. We typically characterize these viruses based on two proteins that are found on the surface of the virus. One is referred to as a hemagglutinin protein or H protein, and the other a neuraminidase or simply N protein.
There are 16 different H subtypes, 9 different N subtypes; so you have a combination of 144 different characterizations of this virus based on the particular H and N types.
The virus that's currently circulating in much of the rest of the world -- that is in fact highly pathogenic in poultry and is capable of producing disease in humans -- is by this characterization an H5N1 highly pathogenic virus. But I think it's important to point out that viruses within that same subtyping can be very different. So, for example, you can have two distinctly different H7N2 viruses, and as is the case with the H5N1 we have two distinctly different H5N1 viruses -- the highly pathogenic form that is producing disease in poultry and in some cases in humans in much of the rest of the world, and this North American H5N1 virus that heretofore has been low pathogenic in birds and is not known to produce any disease in people.
So not all viruses are created equal, even those that would have the same characterization such as an H5N1 are not always the same.
Because of increased disease surveillance testing that we are doing in wild birds in the United States, and given the number of avian influenza viruses out there, it is certainly not unexpected that we would find a number of low-pathogenic avian influenza viruses including an H5N1 virus that we know has been circulating before in wild birds in North America. In fact, this low-pathogenic H5N1 virus has been found on two occasions in wild birds in North America. These were in wild ducks in the U.S. in 1975, and 1986, and more recently late last year in Manitoba, Canada.
I should point out too that according to the International Standards put out by the OIE, or the World Organization for Animal Health, finding of this virus in wild birds should be no basis for any country imposing trade restrictions on the United States and our commercial poultry.
A little bit of additional information about this particular Michigan situation-- the samples in question were collected as part of our routine surveillance program on Tuesday, August 8, and they were collected by some our Wildlife Services employees within the Animal and Plant Health Inspection Service of USDA. The samples were collected at Point Mouillee, which is a game area in Monroe County, Michigan, which is found in the southeastern tip of the state of Michigan.
Screening tests on these samples were conducted at the Diagnostic Center for Population Animal Health at Michigan State University on August 9, and when they came back with positive results for H5 those samples were then forwarded to our National Veterinary Services Laboratories in Ames, Iowa, where confirmatory testing began on August 12.
It was those screening tests originally conducted at the laboratory at Michigan State University that indicated that these birds had been exposed to H5 avian influenza viruses.
With that, let me turn the microphone over to Dr. Sue Haseltine from the U.S. Geological Survey at Department of Interior where she is the associate director for Biology, to give an Interior perspective on this situation. Sue?
DR. SUE HASELTINE: Well, thanks, Ron, and good morning, everyone. I guess from Interior's perspective I'd like to bring you up to date a little bit on the sampling that we're doing in wild birds across the country for avian influenza. As Ron has said, this finding of an H5N1 is not a surprising event to us even though it's in a wildlife species of a resident mute swan. And in fact we have been increasing our surveillance for all avian influenza subtypes throughout wildlife species in this country as sort of an early warning system for this particular strain in Asia.
And just to give you a sampling of that, in Interior we have tested so far over 8,000 samples from migratory birds in this country since early June. About 4,000 of those are from subsistence hunters in Alaska-- the subsistence hunt in the spring harvests all kinds of migratory birds as they return from their wintering grounds to breed, many of them from Asia. And then about 4,000 additional samples have been run on live birds that we know have a life history of spending time in Asia during the wintering months of their life cycle.
In that sampling as a whole, we found less than 2 percent of them to have contained avian influenza viruses of any subtype, and that's about standard for what we would find sampling wildlife species across the country. We tend to find a bimodal distribution in avian influenza viruses. They tend to build up and we find more when we sample in the fall.
But we're about on point, and we are continuing to sample both live birds as they return, especially to the Pacific Flyway and the Pacific Islands, and as I said the spring subsistence hunt.
We've also increased our capability to detect mortality events around the country, and Interior as a whole has responded to about 18 large-scale wildlife mortality events since early June, and none of those have been caused by avian influenza. But that's another increased surveillance that we, and the states, are all looking out for.
DR. DEHAVEN: Thank you, Sue. I think this points out an important thing. It is certainly no surprise that we're here this morning given the level of surveillance that we're doing in wild birds and knowing what we know about the prevalence of avian influenza in those species. It's really not surprising that we have found this particular virus. Certainly we will continue the testing that would be relevant in terms of characterization of this virus. But again the fact that we're here this morning reporting this is certainly no surprise given the volume of testing that we're doing as part of our overall highly pathogenic AI program in the U.S.
And I have to say, too, that it is, I think, a model of cooperation in that some of the testing is being carried out by Department of Interior, some by Department of Agriculture, and much of it by our colleagues in the State Departments of Natural Resources and Game and Fish.
With that, let me turn the microphone over to Dr. Bill Raub who's the science advisor to the Secretary of Health and Human Services for a human health perspective. Bill?
DR. BILL RAUB: Thank you, Ron. I appreciate the opportunity to join you this morning. I reinforce Dr. DeHaven's point that the evidence accumulating here suggests no threat to human health. We see no cause for public health and medical authorities to take any special actions as a result of this information.
We are dealing by all evidence with a matter of wildlife biology. From the perspective of Health and Human Services, we very much appreciate the initiatives of our colleagues in the Department of Agriculture and the Department of Interior for mounting and operating this wildlife surveillance activity.
We appreciate our partnership with them. The response here demonstrates the smooth and effective capabilities and coordination amongst the agencies and augers well should there be the time when a somewhat more troublesome set of information emerges than we have as of now.
All of our agencies have offered a variety of general precautions with respect to such things as dealing with sick and dying animals, which is not the case here; precautions with respect to workplace exposures such as in handling sick and dying animals, which is not the case here but we remain vigilant and prepared.
And again, I appreciate the initiative of our two colleague cabinet departments. Thank you.
DR. DEHAVEN: With that we would like to open it up for your questions and would only ask that you get a microphone before you ask your question.
REPORTER: Dr. DeHaven, Bill Tomson, Dow Jones. You've said before, and correct me if I'm wrong, that low-path can evolve into high path. Is that the case here? Is this something you're concerned about this evolving into a highly pathogenic strain?
DR. DEHAVEN: One of the characteristics about influenza viruses in general is their ability to mutate and mutate quickly, and it's really for that reason that the flu shot that you obtained last year won't protect you from the flu viruses that we'll encounter next year or the year after. It's no different in birds. In fact, these viruses do mutate quickly.
It's only the H5 and H7 subtypes, low pathogenic H5 and H7 subtypes, that have ever been known to mutate into a highly pathogenic form. So the fact that we are dealing here with what looks like a low pathogenic H5 virus would be reason for concern simply because any H5 or H7 virus has that potential.
But let me emphasize again the fact that there is no known exposure of these birds to commercial poultry, and we also know that again wild bird populations have a number of different avian influenza viruses out there. So this is no surprise. We've known that there's been an H5N1 low-pathogenic virus circulating in wild birds in this country for a number of years. So not a surprise. But again, any H5 or H7 virus is of concern from a commercial standpoint in that it has the potential to mutate to a highly pathogenic form.
In the back?
REPORTER: Irv Chapman. I work for Bloomberg. First a factual question. We heard that 8,000 birds have been tested by Interior. Is there an overall number for how many birds have been tested this season and nationwide?
And second, how did this particular swan get the virus or get sick -- or if it's not sick, just get the virus?
DR. DEHAVEN: Let me take the second question first in terms of how this bird might have gotten the virus and its clinical symptoms and turn over to Dr. Haseltine to talk about the numbers of testing.
Again I think it's important to emphasize that these avian influenza viruses are in our wild population. In fact wild birds serve as the reservoir, the ongoing source of virus for avian influenza viruses. So it's not surprising. And in some species of birds the birds are completely healthy and normal, as was the case here. These birds were sampled as part of our routine surveillance program. There was no morbidity or mortality associated with these birds at the time that they were tested.
So what we have are healthy, normal-appearing birds that appear to have been carrying a low pathogenic virus as best we can tell at this point in time.
I mentioned that the cooperative effort between Department of Interior and USDA in carrying out this wild bird surveillance program, Dr. Haseltine mentioned some 8,000 samples collected thus far by Department of Interior-- our USDA APHIS Wildlife Services colleagues thus far have collected in the neighborhood of 2,000 to 3,000 samples. But let me defer to Sue for some more definitive information.
DR. HASELTINE: I think the answer is, we can't really tell in the samples yet because in addition to federal efforts there are also state efforts and university efforts going on. And I guess this would be a good time to put a plug in for our joint information systems, which are being prototyped at the moment. And by this fall, we have a commitment from the whole community to deposit their information in those. And we should, in a much more rapid way by September or October, be able to give you a total that have been tested and where those are. But I'm sorry I can't do that right now.
DR. DEHAVEN: It's important to point out too that while we've been doing a lot of testing in Alaska, because those are the nesting and breeding grounds where these birds are now, we'll be doing a lot of testing in the lower 48 throughout the United States beginning in late August through September and the fall migration season. So much of the testing in the rest of the country will begin late August and continue on through the fall.
REPORTER: Salli Kidd with Hearst TV. What is happening with the birds that tested positive? Are you destroying them?
DR. DEHAVEN: We actually -- it's a unique situation with these particular mute swans in that they are a species of swan that was introduced in the area and as Dr. Haseltine pointed out they are actually residents in this game area in Monroe County. Because of the overpopulation of mute swans and because of the fact that they compete better than some of the native species of birds -- for example the trumpeter swan as well as loons -- we actually had a contract in APHIS with the Michigan Department of Natural Resources to decrease the population of these particular species of birds.
So the animals that were tested were actually part of that reduction in population effort, and we're just taking good advantage of that fact in collecting samples from those birds that are being sacrificed. So these birds in fact were sacrificed and then samples collected from them. Again, there are many more of these species, these mute swans, in that game area. And there is no evidence of any mortality or morbidity, no sickness or dying in that population of birds.
Yes, sir -- gentleman in the yellow shirt?
REPORTER: -- Bridges, Associated Press. Could you explain a little bit the scene, what other bird species are present in this preserve? Have you stepped up testing of those species? Numbers of birds that are there? And also, what might have been the source of the virus? Was it something, was it indeed a reservoir? Is it something that may have recently arrived carried by migratory birds? Just if you could explain a little bit the mechanics.
DR. DEHAVEN: Let me ask Dr. Haseltine to take that.
DR. HASELTINE: Well, I can only give you a general answer to that question. I don't know the specifics. But you know mute swans are a wetlands species as they are around here, so you would expect to have shore birds, waterfowl, and it's a semi-forested area so raptors and passerine birds in the area.
As far as how the virus might have gotten there, as Dr. DeHaven said we've found this virus, this particular strain of the virus, in several other wetlands situations around the U.S. and Canada over the last 20 years, and no doubt this virus is cycled through feces and what not. So that would be my best guess as to how these particular birds picked it up.
REPORTER: To follow up, wouldn't this maybe establish a precedent for the high path mode where it could have made it to these shores? Or as you suggested is it something that perhaps has been present in the background?
DR. HASELTINE: I think it's present in the background in this country and in Canada and cycles -- you know mute swans are an introduced species that while they tend to be fairly resident they move back and forth with weather fronts in open water and all kinds of migratory species then use the same wetlands that they do. So it makes sense to me that this is not a precedent. It's just a normal avian influenza event.
DR. DEHAVEN: Let me clarify with three points. One, we can definitively say this is not the H5N1 virus, highly pathogenic virus that's been found in Asia and other parts of the world. That we know for certain, so it's not the introduction of that virus into North America.
Secondly, we do have reports of a number of different species of birds in this game area, various species of ducks, loons, other types of swans. So there's a number of different species.
And the third point is that we will be coordinating with the Michigan Department of Natural Resources to do additional testing in those species of birds in this particular game area.
But again, not surprising that we would find avian influenza viruses in our native population of wild birds. We know they are the reservoir, and we also know that there's been a low pathogenic H5N1 virus circulating in North America. So here again no surprise that we just happened to find it in this particular area.
Gentleman in the blue shirt?
REPORTER: Scott Foster with NBC News. How many birds tested positive?
DR. DEHAVEN: The samples were collected from 20 birds and two of the 20 tested positive.
Next question? Next, ma'am.
REPORTER: Jane Zhang of the Wall Street Journal. The tests you are conducting in Iowa right now, are they going to be different from the ones you conducted in Michigan and the [inaudible]?
DR. DEHAVEN: There's a number of tests that we run on any of these samples. We have a network of over 50 laboratories, most of them state diagnostic laboratories, state veterinary diagnostic laboratories that are doing the screening test for us. They are doing what's called the PCR, polymerase chain reaction test, which looks for the genetic material of the virus. So that's a screening test that's being carried out at this laboratory at Michigan State as well as the other laboratories in our National Animal Health Laboratory network.
If any of those laboratories find an H5 or an H7 virus, again because of the potential for the H5 and H7 subtypes to mutate to a highly pathogenic virus, those samples then go to our National Reference Laboratory, which is the National Veterinary Services Laboratory in Ames, Iowa.
When samples are received there, as they were in this case, we repeat that PCR testing for H5 and H7. We also do a PCR testing to determine whether or not it's an N1 test. And so it's those two PCR tests conducted in Ames that show that we have the antigens compatible with an H5 and N1.
The additional testing that we're doing would include sequencing the genetic material. What is the sequence of the genes, and is that consistent with a North American strain or an Asian strain? The fact that this was compatible with our North American virus and not compatible with the Asian high path avian influenza virus that we are able to say that this is not the incursion of that Asian high path H5N1 virus.
There's also another test to determine pathogenicity or really two ways to determine pathogenicity. One is, looking at that sequence, that gene sequence. It's through that gene sequence testing that we're able to say that from a genetic standpoint this looks like a low pathogenic virus.
But the other test that we run involves inoculating baby chickens, eight baby chickens with this virus and then the test is that if six or more of those baby chickens die within a 10-day period then it would be characterized as a highly pathogenic virus.
So we're just starting that work. We have to grow more virus before we can inoculate it into the baby chickens. And so we're estimating it could take us upwards of two weeks before we would have that second test done that determines pathogenicity.
So two pathogenicity tests, one that looks at the gene sequence, one that looks at the impact on baby chickens. Either one or both that came back highly pathogenic, we would be bound to call this a highly pathogenic virus. The first test is done, indicates a low path virus. The results from that second test which should be forthcoming in the next two weeks.
Next question, please?
Very good. I see no other hands. We appreciate your time and attention. Again, we'll continue this testing that's being done on these samples, and as we get the additional results we'll certainly make them public to you.
MS. TEUBER: I will just add that you should have packets that have both the news release about what has just been discussed, a fact sheet that compares low path H5N1 to high path H5N1. I know that's a little bit confusing, so hopefully that will help to clarify that. And also a fact sheet about our testing procedures because that too is somewhat complicated, and that sort of walks you through step-by-step what tests are conducted and where.
For those not present listening via telephone or on the web, all this information will also be posted on the USDA website.