Press Briefing Transcript

CDC Update: Anthrax Investigation Telebriefing Transcript

November 30, 2001

CDC MODERATOR: Good afternoon. We have with us today Dr. Jeffrey Koplan, the director of the Centers for Disease Control and Prevention. We also have joining us Dr. Tony Fauci from the National Institutes of Health, and Dr. D.A. Henderson from HHS's Office of Public Health Preparedness.

Dr. Koplan will make a few brief opening remarks, and then we will open it up for questions. We ask that you limit your questions to one per person so that we might get to as many people as possible. Thank you.

Dr. Koplan?

DR. KOPLAN: Good afternoon to you all. What's going on is we continue to have intensive investigations with the Connecticut State Health Department in Connecticut looking at the fatal inhalation anthrax case in the 94-year-old woman from Oxford, Connecticut. We obviously continue to focus investigations in New York on the unexplained inhalation case and death there that we have been looking at for several weeks now.

Back to Connecticut. As part of the ongoing investigation there, we and the Connecticut health authorities, have looked at all possible avenues of transmission, and they are all being vigorously pursued, including the mail. The Connecticut Public Health Lab has tested hundreds of environmental assessments from the victim's home and Postal facilities in areas around Oxford and Seymour, Connecticut, looking for possible clues for the source of exposure to anthrax. All of those tests up till now have been negative.

The U.S. Postal Service was asked to check as to whether, through their systems, whether they could find out whether any letters were going to this same Oxford-Seymour area where the fatal case lives and whether any of those had passed through on October 9th the same sorter that had processed the Leahy and Daschle letters.

And they only found letter that was identified as such, and the people who had received that letter were identified, and they were visited. The letter was retrieved and tested, and swabs from that letter indicated that it was positive for anthrax, suggesting cross-contamination with either the Leahy or the Daschle letters or the sorter itself as it passed through the central office in Trenton.

This is not an unexpected finding. We have had other positive cross-contaminated mail in other locations, and the recipients of this letter in Connecticut are well, and they have no evidence of anthrax. Nevertheless, while we may never be able to determine the exact way the woman in Connecticut was exposed, we and our colleagues continue to aggressively pursue mail as one of many, but one possible source, and we'll continue to do so.

Previous incidents of, for example, cutaneous anthrax in a resident in New Jersey suggests that cross-contamination is a potential risk, albeit a low risk, and millions of pieces of mail have gone through those known-contaminated facilities, but active surveillance in many, many states and across the country has suggested very few cases of illness have occurred.

So, at this stage, we're 7 weeks past October 9th, but have found this one letter with anthrax on it in Connecticut, and this doesn't focus an answer on what caused the case in this woman in Connecticut, and we're still looking to see what are the possible exposures that she might have had.

CDC MODERATOR: We'll take questions now.

AT&T MODERATOR: Thank you. Ladies and gentlemen, if you wish to ask a question, please press the one on your touch-tone phone. You will hear a tone indicating you've been placed in queue, and you may remove yourself from queue at any time by pressing the pound key. If you're using a speaker phone, please pick up your handset before pressing the number.

Our first question will come from the line of Andrew Revkin [ph] with the New York Times. Please go ahead.

QUESTION: Hi. I was hoping you would elaborate on something you said a minute ago, which was when you said we've had other positive cross-contaminated mail in other locations. Was that--do you have--for example, have you and/or the Postal Service already generated some kind of a map, essentially, BF [ph] bar codes in computers, backtracking of mail that went out through Hamilton? In other words, is there sort of a grid or a map of possible Oxford?

DR. KOPLAN: Well, we don't have it down to home levels. What we have that indicates cross-contamination is the fact that, as far as we can tell, the target letters didn't go through every one of the places where we have some positives in Postal facilities in Washington, D.C. Washington, D.C., is where the most extensive testing has taken place; you know, radiating out from the initial contamination at Brentwood, and it has been found to be positive in other places.

And, again, without having the individual pieces of mail with spores on them, there is evidence that spores travel to these other places, which is a form of cross-contamination.

In addition, we have one case in New Jersey of a woman who was not part of the Postal system, and we could find no evidence that she was targeted with a letter, and who developed cutaneous anthrax. And, again, the working assumption there is that she was contaminated or exposed to anthrax through mail that had passed through one of those Post Offices, and thus became "cross-contaminated" with anthrax.

QUESTION: Is she the only case you're talking about, though, in other words?

DR. KOPLAN: There's a Postal worker in New Jersey who also didn't have a direct exposure to sorting machines and places where you would say it's a primary exposure, and so our assumption was [inaudible]--

QUESTION: Yeah.

DR. KOPLAN: --that it was again cross-contamination with anthrax.

QUESTION: Just a last tiny question or update. Not to house level you said, but do you have it to Post Office level? In other words, do you have a map of [inaudible]?

DR. KOPLAN: Ultimately the valley--yeah, we do have. We've been learning a lot more about the postal service, and that there is cross linkage, obviously, with every post office in the country at some level, and every one of our homes and businesses. So we have been moving from place to place. You know, when we find a facility like Brentwood or Hamilton Township, in which these letters have passed through with [inaudible], that we then have moved out with the postal service to do testing as we move away from these sites. And we have information with, you know, some positives and many negatives for many of them around. 

The most extensive testing there has been in the Washington metropolitan area and in New Jersey.

CDC MODERATOR: Next question, please.

AT&T MODERATOR: And our next question will come from Seth Borenstein at Knight Ridder. Please go ahead.

QUESTION: Yes, Dr. Koplan, if you can revisit--does this cause you to revisit the whole LD-50, you know, the lethal doses of--for inhalation anthrax and does it--how does that relate to someone who's obviously got a compromised immune system at age 94? In other words, are people--should people with compromised immune systems be a little bit more nervous about their mail than other people, and are you going to do something to check to see if that 8000 to 10,000 range that you have been talking about in the past for inhalation anthrax, maybe that is wrong or maybe it is not for the general population and more aimed at younger people?

DR. KOPLAN: Seth, thank you. Let me reemphasize, we have used--we have mentioned in the past that the LD-50, the lethal dose 50 for anthrax spores was 8000 to 10,000 tested in macaque monkeys, not in people, and so we do not have adequate information on dose response for this disease, that it could be lower for some people and higher for other people. And the point you make about people with lowered immunity, could they be infected by a much lower dose, you know, is a very appropriate question and hypothesis. As in many other diseases, folks with lowered immunity may well be more susceptible. Does someone who is 94 years old have a less robust immune system than someone who's 35? Absolutely. And that may have played a role in this. We don't know. 

We would love to have good information on dose response, and I think some of the facts that probably go into this, and my colleagues Dr. Henderson and Dr. Fauci, may want to weigh in, but some of the factors that would go into this is, is all anthrax the same when it comes to the dose response, and I would suspect the answer is not, that it may depend on the physical properties as to how likely it is to infect someone at a lower dose, and also then the host plays a role in it as to what shape they're in for the receipt.

Should people that--Tony is--Dr. Fauci is much closer to clinical care of patients with immune deficiencies and so I think he might be better to answer your question.

QUESTION: Follow-up here.

DR. FAUCI: You bring up a very good point that we've actually discussed, I think, repetitively over the last couple of weeks. The question that you asked Dr. Koplan, he answered quite appropriately. You've got to be careful when you talk about LD-50 because LD-50 means the dose was 50 percent of the animals in the study that were killed. But if you look at a bell-shaped curve of responses, that means that some monkeys had to take a lot more spores to get killed and others had to take much, much fewer. So if you're talking about an LD-10 or an LD-1, which would mean what is the dose that would kill only 1 percent, it is conceivable that you may get down to a very low number.

If you compound that with the hypothetical situation that you might have a combination of a fraction of the population would get infected from an inhalational exposure with much less spores, which is quite conceivable and biologically quite feasible, and that if you compound that with a--what we call a diminished host defenses or the diminished capability of the body to deal with whatever microbe you're talking about, and in this case a 94-year-old woman, those two things compounding each other could be one explanation of what you're talking about now.

I'm not saying that it is, but it certainly needs to be put on the table as a possibility, among others. And the others may be we still don't know how it happened. This could explain it, but we don't know for sure.

QUESTION: To follow up--

CDC MODERATOR: Next question, please, from the next reporter, please.

AT&T MODERATOR: Our next question will come from Kim Dixon at Bloomberg. Please go ahead.

QUESTION: Hi. What are officials advising people with weak immune systems and older people to do with their mail, with the very small percentage of people who may be at risk for cross-contamination. And also can you just clarify where the number 300 is coming from, where the estimate is coming from, and does it mean--is that all mail that was slated to go to Connecticut?

DR. KOPLAN: I think that 300 is based on the numbers of letters that went through a given sorter in some few seconds during the course of the sorting. So there's really nothing magical about that number. During the course of a couple of hours, I think tens of thousands of letters go through the sorter, and with the sorter agitating the air all the time, the neighboring sorters become just as prone, I think, to becoming contaminated, and so that limiting it to some finite or very small number of letters in this just doesn't work, I think, in terms of potential spread of a cross-contaminant.

Tony, do you want to address the immunologic deficiency point?

DR. FAUCI: I'm sorry, the question about the immunologic deficiency, I thought I just mentioned.

DR. KOPLAN: Oh, I'm sorry.

DR. FAUCI: In other words, what would we recommend? You know, it really is going to depend as we and others have said before, it depends on what you're comfortable with. I mean obviously if you want no risk in a situation in which there's mail, then you won't have people who have compromised immune systems handle mail. But I don't think one can go that far with what we know now, because if you look at the number of letters that have gone through a similar process as the letters that were just described by Dr. Koplan, you're talking about millions and millions of letters. 

So what would be the risk of someone getting exposure like that? The risk would probably be one in several millions. Now if someone wants to be risk-free, then you either avoid that or, as Dr. Koplan has said in the past, you wash your hands and be careful or you don't pick up a letter and put it in front of your nose and start sniffing it accidentally or something like that. It really depends on what your level, you being the party involved, be it an older person or an immuno-suppressed person, is comfortable with.

The closer you want to get to zero risk, that's how you handle it. But the risk is still very, very low, but it's not zero, as we've seen, because we still have unanswered questions, and as long as you have unanswered questions, you cannot say with confidence that there's no risk.

CDC MODERATOR: Next question, please.

AT&T MODERATOR: Our next question will come from Laura Meckler, Associated Press. Please go ahead.

QUESTION: Thank you. You said that you have only found one letter that passed through that New Jersey--contaminated New Jersey sorter that went to Oxford. I think that's what you said.

DR. KOPLAN: I think it's one letter that went to Connecticut.

QUESTION: That went to Connecticut. So does that mean that--I mean why would we believe that this woman was infected through the mail if this was the only letter that went through? How is it that she would have received a letter that was contaminated? Or are you thinking of a double cross-contamination, or where it was--

DR. KOPLAN: Let me just correct something. I believe I misspoke, which is that--there was one letter that went to the zip code that surrounds where the fatal inhalation anthrax patient lived, or the neighboring zip code. Could there have been other letters that came through or went some other places? We're not sure. We're working with the postal service now to try to ascertain whether there was other mail that came through that way.

QUESTION: So there was only one letter that went to her zip code?

DR. : There's only one letter that we've identified so far, and actually it wasn't the patient's zip code. It was a zip code that's a neighboring, but in which the housing is within a couple of miles of where the patient was.

QUESTION: So have you checked to see if there was any mail that went from New Jersey to the 94-year-old woman's zip code?

DR. : Yes. We are looking at that, and I believe the Postal Service has not found one for that date, but we're also asking them, and they're looking for, other dates in that same area of around October 9th, to look for other letters going more forward from that.

QUESTION: You would need, in order to explain her exposure, there would--I mean it's interesting. I didn't know you could actually find out from the Postal Service what mail passed through New Jersey and went to Oxford, Connecticut. So you'll be able to find out whether any mail after October 9th went from New Jersey to--

DR. : They have varying levels of information for different localities. And so we're only--we're working with them to see what information they can generate, so there's no guarantee that for every place and for every time you can get the same detailed level of information, but that's what we're trying to see whether we can get.

I think we should keep in mind though that the patient's house has been tested, and in her house there have been no positive samples either from mail that she had or clothing or other environmental areas. But what we're trying to do is, you know, in that we have not gotten an answer, is reexamine every possible source of spread including inhalation asthma from other mail.

CDC MODERATOR: Next question, please.

AT&T MODERATOR: Next question will come from Robert Bozell, NBC News. Please go ahead.

QUESTION: Hi. Your question--we're just all, I think, trying to get a sense of how important you think that this discovery is. Is this a clue in this investigation? Is it possible that there was cross-contamination in the Seymour Post Office with a letter that went to the 94-year-old woman, or is this a completely incidental finding that is interesting but has nothing to do with the investigation?

DR. : I think it's interesting. It's not something new in that we've seen cross-contamination before. We've known that mail can go to other parts of the country that were not involved prior to this and have spores on them. And that's about what it is.


CDC MODERATOR: Next question please.

AT&T MODERATOR: The next question will come from Rick Weiss, Washington Post. Please go ahead.

QUESTION: Thank you. A pair of questions. One is, you know, given--I recognize that nothing is certain yet, but given the evidence that's accumulating, that it's possible at least for a modest, if not minuscule dose of this stuff to cause inhalation anthrax in a very susceptible person. Why are you stopping short of making a real recommendation for at least the elderly or immune-compromised to take certain precautions when they open mail, especially in that--I think, Dr. Fauci, your millions and millions for a denominator isn't really the right number to use if we're talking about old people. Yes, knowing pieces of mail went through, but probably very few of them, to people in their 90s, so the odds are probably higher than 1 in a few million.

The first question is why not make a recommendation to people in that category itself?

Second question is can you tell us anything about the pulmonary health of Ms. Kathy Nguyen?

DR. : Rick, you're asking the wrong person about recommendations.

QUESTION: Right. I'm asking Dr.--

DR. : But, you know, the NIH doesn't make recommendations about who should or should not handle mail.

QUESTION: I'm asking that part of the question to CDC I guess.

DR. : Happy to answer that. I think it becomes--if we don't have it--you know, normally we make recommendations based on adequate data and [inaudible], and in this case we don't. Now, we certainly acknowledge that this increasing evidence--but we've had evidence before of cross-contamination--makes people nervous. It's uncomfortable to know that there's anthrax spores on letters out there, and I would love to be able to say definitively, "Here are the things you need to do, and this will protect you and this is an appropriate step to take." But we just don't have information that permits us to do that. And I think the best we can do is say, "There's a range of steps you can take."

You know, is it 90 that's the cutoff? I mean, part of the problem with doing a guideline or making a recommendation is, is it 94-year-olds or is it 90-year-olds, or is it 80 years, is it 75? At what level of immune deficiency do you need to worry about?

So I think the best we can say for all of us is if you're uncomfortable about this, if you think because of age or other conditions that you are somehow immunologically compromised, then there's steps you can take. And the simplest would be washing your hands after you've handled the mail, and keeping that mail away from your face. To an extreme, not handling the mail at all, and having someone else do it for you, as Tony, as Dr. Fauci indicated. I would not go to that extreme. But if you say to me, well, do you have a scientific basis to say do one or do the other, we don't have that level of information yet.

CDC MODERATOR: Next question please.

AT&T MODERATOR: Next question will come Megan Garvey, Los Angeles Times. Please go ahead.

QUESTION: I wanted to follow up with the idea of not holding mail close to your face. Do you have any reason to believe that Mrs. Lundgren had poor eyesight or difficulty reading, and may have looked at mail very close to her face?

DR. : We don't know. She did wear glasses. Some of us, as we age, hold mail farther away than closer. We don't know what Mrs. Lundgren did. She read though. She got magazines. She was, I'd say, an active and vibrant 94-year-old person, but the actual question we've asked did people observe how close she read, it was not noticed.

CDC MODERATOR: Next question please.

AT&T MODERATOR: Next question will come from Greg Latsky with New Haven Register. Please go ahead.

QUESTION: Yes. You said that this letter to Seymour was the only one that went to a zip--the Lundgren zip code or a neighboring zip code. Can you tell us, were there other zip codes in Connecticut where any of these 300 letters, suspected letters went to, and how many states these--the other letters went to out of those 300?

DR. : Again, the 300 is not a--I don't think that's an important number, to tell you the truth. It's just an--and I'm not quite sure why that's been fixed on. The best information for postal deliveries in Connecticut and other parts of the facility would come from the Postal Service, and I just don't have that information in front of me.

CDC MODERATOR: Next question please.

AT&T MODERATOR: Next question will come from Susan Denser, NewsHour with Jim Lehrer. Please go ahead.

QUESTION: Yes. I'm interested in what all of this could tell us about other possibilities of cross-contamination now that may have taken place. You mentioned a New Jersey woman. But what about the infant at ABC? What about these other instances where no pieces of mail have been identified? And of course, Ms. Nguyen as well. Doesn't this cross-contamination possibility, if it happened in this case, raise up that possibility of those explanations applying in those other cases as well?

DR. KOPLAN: Well, I think we have more compelling [theories]* of exposure for most of the other cases, even where a letter wasn't recovered, and in the instance of the infant who developed cutaneous anthrax, there were--one contaminated letter, and a target letter in that office, and opened in [inaudible] and in the room where that infant visited. The infant was present both on surface where that letter may have rested or been opened. And so that says a different scenario than one letter that rubs against another letter and then that letter passes on some spores.

Again, I think back to the point that we had before, is this finding of the spores on a letter in Connecticut doesn't really change whatever scientific information we've got so far because there is evidence that there has been, quote, cross-contamination with anthrax, both through a couple of cases in New Jersey and finding a positive anthrax in locations where it wouldn't have gotten unless there had been cross-examination.

So the cases we've got so far I guess largely fall into three categories. One exposure related to mail, handling mail, opening mail and in a mail room in a postal facility with a sorter and a variety of different situations relevant to mail. And then two cases where we have no clear exposure and have not been able to identify why those two people got this disease.

CDC MODERATOR: Next question please.

AT&T MODERATOR: Next question will from Sean Laughlin, CNN. Please go ahead.

QUESTION: Hi, doctors. Do you have any information on the--let's call it the Seymour letter? I just haven't heard any detail. I mean in terms of what kind of letter was it, where is the letter now, and everyone has talked about the envelope. I'm wondering the letter inside this envelope, what did it show?

DR. KOPLAN: I don't have the--it was not a threatening letter. It was a letter that couldn't be construed as something that would have contained forged or sent intentionally to harm someone. I don't know whether it was a bill or a personal letter or a brochure or what. It was picked up by the Connecticut State Health Department and brought to their lab for testing, and they have it. I haven't seen or have no more details on the letter contents myself.

CDC MODERATOR: Next question, please.

AT&T MODERATOR: Next question will come from Monica Conrad, ABC News. Please go ahead.

QUESTION: Hi. I'm sorry. I'm going to kind of go over old territory again.

Including today, you've been saying that you cannot get inhalational anthrax from cross-contamination of mail. That has always been something you guys have said.

DR. KOPLAN: No, we have not. We have said it is highly unlikely.

QUESTION: Highly unlikely.

DR. KOPLAN: And I would still it's highly unlikely, but not--we've said repeatedly that these things are highly unlikely, but are conceivable or possible. As Dr. Fauci just said, using the mathematical expression of a bell-shaped curve, that in rare instances smaller numbers of spores or a lower infecting dose could infect people, particularly if they were susceptible. But things can be unlikely and still occur.

QUESTION: Okay. And Kathy Nguyen, you didn't talk about what the condition of her lungs may have been or if she had any compromised immune system.

DR. KOPLAN: She had not had measurements that would have documented that, but she had no underlying chronic disease. She was healthy. She was on no pulmonary medication. She had visits to doctors before, but there were no records of anything that would have suggested some level of compromise.

QUESTION: Thank you.

CDC MODERATOR: Next question, please.

AT&T MODERATOR: The next question will come from Dave Altamari [ph] Hartford Courrant. Please go ahead.

QUESTION: Yes. Hi, Doctor. The fact that this letter that went through Seymour and tested positive for anthrax and the Post Office that it would have gone through was tested twice in the last month and a half and both times--at least twice in the last month and a half--and both times the tests were supposedly negative. Does that say anything about some of the testing that's been done or call into question some of the testing that's been done at Post Offices, other Post Offices across the country?

DR. KOPLAN: It says a couple of things. One, it says that where there's massive contamination, you can pick the stuff up all over. Where there's very spotty or scant contamination, whether it's a letter or a surface, it can be very hard to isolate this stuff. So here you've got a letter with a couple of spores on it, maybe those are the only ones that were around or maybe a couple dropped off en route, but it doesn't necessarily question the validity of the testing done; it just may be very hard to get positive results when you have very small amounts of anthrax.

CDC MODERATOR: Next question, please.

AT&T MODERATOR: The next question will come from Sara Luke [ph], the Wall Street Journal. Please go ahead.

QUESTION: Thank you. The Hart Building clean-up that's supposed to start this weekend, and I was told that EPA is going to be consulting with CDC on what safe time is to open it. And I wondered whether this idea of a small amount of spores infecting people who are older or immune compromised somehow complicates that decision and whether you can ever really know for sure that that building is safe for everyone.

DR. KOPLAN: I think the case of surety and 100-percent positive is probably unlikely in any part of this. I think what will go on with both EPA and with us working with them is to take every effort and extraordinary efforts to remove every infectious spore, potentially infectious spore, from the building. And the way that's been operating is they've been putting out various culture plates looking to see if there are any spores present, and then cleaning up. And if there's still positive spores present, then they keep cleaning up.

I think that there's no intention to open the building until everyone feels very comfortable the people who are working in there or visiting in there will be safe, and so that's continuing. Again, this is new territory for both EPA, and certainly for us. EPA is charged with these building clean-ups all over the place for environmental and chemical substances, but we haven't had this experience before as a country in how do you clean up a building like this when something like this happens.

D.A., I don't know that you're aware of any other international information that would be germane to this.

DR. HENDERSON: No, I don't know of any, Jeff, but I do think we need to remind everyone that we don't yet know that this woman was infected by a very few spores. That's purely speculative at this point. We're still searching. We're trying to identify how these people are infected, and so I think to leap to the conclusion at this point that a very few spores in any place poses a serious risk is, I think, going beyond science at this point.

I think we're sharing the information with you, as it becomes available, and the only thing we can say is that you have to share with us our frustration in not being able to give definitive answers, but that we're moving along accumulating pieces of evidence which we hope will give us a much more definitive idea of risk and under what circumstances.

CDC MODERATOR: Next question, please.

AT&T MODERATOR: The next question will come from Kristin Reed with Bloomberg News. Please go ahead.

QUESTION: Hi. Thanks very much. I just wanted to kind of clarify again, we've talked, and Governor Rowland has said on a number of occasions that, you know, since we're past this particular 60-day or 45-day window, that they don't expect anyone else to get sick.

But as far as [inaudible] and there is this low risk of cross-contamination, I wonder if we're really out of the woods yet.

DR. KOPLAN: Well, we're certainly not relaxing our guard, and we remain extremely focused on looking for other cases and looking for any other areas of contamination in Connecticut. However, as you pass each day and each week away from whatever you thought the initial source of contamination is, there is a decreasing probability that you'll see more. But as you say, if there are piles of the stuff sitting somewhere, they could pose a risk, but we've looked hard, and again, in every--of all the specimens we have taken in this area and some other parts of Connecticut, I mean we've looked through the postal service, this is the only positive we've had.

CDC MODERATOR: We'll take one more question, and then if you had a final comment, if you wanted to make one from Dr. Fauci or Dr. Henderson, if you had a comment you wanted to make.

AT&T MODERATOR: Okay, our last question will come from the line of Paul Ziebower, New York Times. Please go ahead.

QUESTION: Hi, Doctor. Thanks. My question is this. You know, you've said, Dr. Koplan, earlier that this isn't exactly--it's interesting news, you said, but it's not exactly something new. What I'm wondering is if it's not something new or earth-shattering towards your investigation to find this, I believe it was one single spore on this letter in Seymour, how does it change the way that you go about, if at all, the way you guys are going about your investigation? And does it--does the finding of this one spore, if I'm correct about that, increase the--or I should say make more likely a theory that perhaps it was not a 10,000 spore, but a handful or even less spores that could have infected Ms. Lundgren?

My question is does it raise even more possibility in your mind that this wasn't an envelope full of anthrax powder that she may have gotten, if she indeed got a letter, but it was a letter that may have crossed once or twice in the mail and then had only a couple of spores which she then touched and maybe rubbed her nose with it or something like that?

DR. KOPLAN: I think what you just described is a possibility, and we have to be [inaudible] with the possibility. I think the frustration we're in now, the difficulty we're in, is after very intensive investigations going on over a couple of weeks, we are no further along in being able to argue the merits of what you've just described versus any one of a number of other possibilities. I think we can say it's not naturally occurring, but we can't do much better than that.

On the question of the dose responses we've had, we've discussed before I don't think this letter in Seymour argues that one way or another. We just don't know what that number of spores is that's necessary to cause an infection of inhalation anthrax in people with a variety of different immune states, and so we don't have that information.

Has it changed the way we're doing this investigation? No. We're still--we have a large team out there working with the Connecticut health people, we're coordinating our investigations in New York and Connecticut to see if there's shared information that will be helpful. We are visiting and revisiting the home and every place this woman's been, looking for other clues and more specimens and samples. We're reinterviewing people. We're trying to think of every possible route of exposure and we'll do it over and over again, but at the moment we really haven't come up with one of these routes that's more likely than another.

CDC MODERATOR: Do we have a final comment from Dr. Fauci or Dr. Henderson?

DR. FAUCI: Just getting back to one of the questions someone asked, we all want to have solid scientific evidence to make conclusions. When you don't have that--I mean if you had a letter that was identified in the woman's home and you saw that there were very, very few spores on there and she got inhalation anthrax, then you can more definitively talk about the relationship between numbers of spores and the probability or not of an older person or a person who has compromised host defenses getting inhalation anthrax. But what we're dealing with is a hypothesis based on a hypothesis. You're looking for some sort of connection and you find a spore in a letter that may have been in contact with a letter that this woman may have been in contact with herself.

So the hypothesis one is is this a letter- related event? And as Dr. Henderson said, we still don't know that that's the case, and whether there was something else going on. But given the information you have, the next obvious question that any rational person would ask is, well, supposing it is a tertiary contamination, what does that tell you about dose response vis-a-vis inhalation anthrax? 

So if you take the first hypothesis and say okay, we're going to give you that even though we don't know it's true, then this is the next rational place that you would take that. So it becomes very difficult and very frustrating because you want to give answers, but it gets more and more tenuous as you get further down the hypothesis based on the hypothesis. At the end of the day we're still not sure why this woman got infected.

DR. HENDERSON: As I think--Dr. Henderson again. And I'd suggest what is the significance of this finding, and I think the significance is that after all the search, the tremendous amount of search, there has at last been a trace of anthrax found on something, which is really quite remarkable. Does it really have anything to do with the case at all? We're not certain, but the significant thing is that there is evidence of anthrax on a letter, and I don't think we can go very much beyond that. 

I think the point is that we're trying to keep everyone currently informed as to just where we are and any significant finding is being brought forward as we discover it. And with that, I'd just say thank you all very much for attending.

CDC MODERATOR: Thank you very much.

AT&T MODERATOR: Ladies and gentlemen, that does conclude your teleconference for today. Thank you for your participation and for using the AT&T executive teleconference service. You may now disconnect.

[End of conference.]

* Note: Inserted for clarification

Listen to the telebriefing

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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES