Div. of Media Relations
1600 Clifton Road
Atlanta, GA 30333
Fax (404) 639-7394
Update on Anthrax Investigations
with Dr. Bradley Perkins
November 2, 2001
CDC MODERATOR: Thank you. Good afternoon.
Our speaker this afternoon is Dr. Bradley Perkins, one of the lead investigators in the anthrax investigation. Before I turn the tele-briefing
over to Dr. Perkins, just another reminder that these tele-briefings will be hosted every day, Monday through Friday, through the end of this
month, except Thanksgiving. The tele-briefing telephone number will remain the same each day, and that is 866-254-5942.
DR. PERKINS: Good afternoon. Let me make a few brief comments, and then I'll take some questions.
We continue to see an evolving epidemiologic picture associated with the anthrax-related bioterrorism attacks in the United States. And as that
situation evolves, so too will our public health response to particular situations.
We're currently focused on protecting the safety of persons who handle the mail or who are otherwise victims of this tragic situation. We have
great concerns for mail handlers who have been the highest, the most frequent target of these attacks, and we have been very pleased with the
opportunity to collaborate with the U.S. Postal Service in developing what we feel are prudent measures to really emphasize the safety of mail
handlers in a variety of occupational and nonoccupational settings.
I'd be happy to take some questions.
AT&T MODERATOR: Ladies and gentlemen, if you do have a question, please press the one at this time. You will hear a tone indicating you've
been placed in queue. You may remove yourself from queue at any time by depressing the pound key.
Our first question is from the line of Andrew Revkin [ph] with the New York Times. Please go ahead.
QUESTION: Hello. Thanks for doing these briefings.
I had a question about the fatal cases so far. In autopsy or reexamination of these cases, can you determine anything about the amount of the
dose that the person experienced by looking at the lungs or were there multiple sites of initial entry into the lungs, that kind of thing? And I
have a quick follow-up.
DR. PERKINS: That's a good question. Autopsies have been done on the patients that have died with inhalational disease during the course of this
investigation. And it is very difficult, we'd like to be able to tell what the initial inoculating dose was, but it's really impossible to do
that with the autopsy.
What we can say is that the autopsies that have been done have been completely consistent with an inhalational route of exposure, so that there
is not confusion here between a cutaneous or a skin exposure or an inhalational exposure. But in terms of dosage, I'm afraid we can't really
draw any conclusions in that regard.
QUESTION: Okay. I have a couple of tiny questions about the environmental testing. Are the swab tests that are the predominant means being used
right now, are those simple positives or negatives or are they quantitative?
And, separately, some Postal Service briefings recently said CDC had been reporting that some samples, some of these trace samples, have been
described by CDC as "medically insignificant." I didn't know if you had a definition yet for when, in a facility, you get what you
would call medically insignificant findings. This is important in terms of when people reoccupy these buildings.
DR. PERKINS: Environmental sampling for detection of Bacillus anthracis spores during this investigation has been done for a variety of
purposes. One, in the context of urgent epidemiologic investigations trying to find out where individuals may have been exposed, and the
situation in New York City right now is a good example of that.
Environmental sampling has also been done in the context of criminal investigations to try to trace the route of a suspect letter. And the
sampling that was done by the FBI in the AMI building is a good example of sampling for that purpose.
The other thing that's going on, other major reason sampling is being done is to prepare to clean up contaminated buildings. And each of those
different reasons for sampling dictates a different sampling strategy. And in some cases, we are moving to quantitative sampling of environment,
both quantitative sampling of air and surfaces that we think may be contaminated.
One of the current public health challenges is trying to characterize the health risks that are presented by environmental contamination. We
know that in the United States there are natural areas of environmental contamination, and in those areas, you know, animals get sick from
anthrax, and there's anthrax spores in the soil, and we don't see human disease in those settings.
So we know that there is some, in some areas, some normal level of background contamination. Now we don't have a lot of experience with Bacillus
anthraces spore contamination in occupational settings, and we are trying to define in the context of this investigation what level of
contamination presents a risk for cutaneous anthrax or for inhalational anthrax.
CDC MODERATOR: Thank you.
AT&T MODERATOR: Our next question is from Pete Williams with NBC News. Please go ahead.
QUESTION: My question is, first of all, to follow up the last one, why can't you tell by an autopsy where the spores originally entered the
lungs? Is it just such a mess that you can't really tell where it started? Can't you do like an arson investigation and find out where the fire
started in the lungs? And in the New York investigation, given that the samples are negative in the apartment and the work place of Ms. Nguyen,
are you thinking about going back and doing more sampling on the view that it must be in there somewhere?
DR. PERKINS: I'll take the first question. The uptake of Bacillus anthraces spores by the human body is pretty complicated. What we can say is
that the autopsies that have been done on inhalational cases are completely consistent with that route of infection. And what happens in the
process of spore uptake is that very--you know, these spores come into the distal--the very peripheral parts of the lungs. They get picked up by
inflammatory cells and taken to lymph nodes where they multiply to very high numbers, and those are lymph nodes in the mid-chest region. The
bacteria multiply to very high numbers and then spread throughout the body.
So that the actual entry event is a very innocuous event in the body, and it's really when the bacteria get transported to these centrally
located lymph nodes that the infection really takes off and the bacteria replicate at the very high numbers and then spread throughout the body.
In terms of additional environmental sampling around the most recently confirmed inhalational case in New York City, what has been done thus far
is a very rapid sampling of the places that were thought to be the highest yield in terms of potential sites of exposure.
Right now the New York City team, local public health officials and CDC, are moving to extend the amount of sampling done in the areas we think
are most likely, as well as the range of sites that are sampled to try to develop, to try to recreate the circumstances for exposure in that
CDC MODERATOR: Thank you, Pete. Next question, please.
AT&T MODERATOR: And that's from the line of Seth Orenstein with Knight Ridder. Please go ahead.
QUESTION: Yes. The continuing environmental sampling, there are some experts who say that the tests aren't sensitive, have high false positives,
high false negatives, and gives you no real--either gives a false sense of reassurance or a false sense of scare, and that we're in a wild goose
chase of testing.
Can you respond to that, and can you tell us what are the sensitivities of the environmental tests that are being done, how many spores are
needed for them to pick them up, in other words? And what is the rate of false positives and negatives?
DR. PERKINS: There are a variety of technologies that are being applied to environmental sampling, and there are a variety of people doing
The strategies that are being used in the public health community, those strategies being used by CDC and state and local health departments
rely on culture, and that is taking a swab or an air sample from an environment and actually putting that sample on a culture plate where the
That method is extremely sensitive. It actually has the ability to pick up a single spore, and we believe that it does so, you know, in a
Others who are doing environmental testing are using other technologies, and those include some of the field-deployable rapid detection
technologies. Those technologies have been, certainly in the hands of CDC, have been incompletely validated or not validated to date, and it is
our impression, based on available data, that those techniques have a sensitivity that is much less than culture.
So in the instance of a culture that can actually pick up one to 10 spores, some of these other technologies you may actually have to get 10,000
spores to get a positive. And I think that that's where some of the confusion is coming in around the sensitivity of spores.
CDC, state and local public health agencies are relying on culture testing of samples. That method is highly sensitive.
CDC MODERATOR: Thank you, Seth.
AT&T MODERATOR: Our next question is from Charles Aronstein with L.A. Times. Please go ahead.
QUESTION: Hi, there. I have a couple of questions. First is I was looking at your deployment list from yesterday, and it looks like you have
three people in Phoenix, and I was just wondering why that was.
And then the second question is at what point, if there isn't another case of either cutaneous or inhalational anthrax that's diagnosed, will
you begin pulling back some of the epidemiologists and others who are in the field, pulling them back to Atlanta?
DR. PERKINS: Yes, we are in the process of constantly shifting, either bringing people back out of the field or redeploying people as dictated
by the course of the investigations. In regard to the epidemiologists deployed in Arizona, CDC routinely assists state and local health
departments in surveillance for infectious diseases around special events, such as the World Series. I believe that's what those epidemiologists
were involved in Arizona.
CDC MODERATOR: Thank you. Next question, please.
AT&T MODERATOR: That is from Elizabeth Cohen with CNN. Please go ahead.
QUESTION: Hi, Dr. Perkins. First of all, thank you so much for having these conferences. They are very helpful. I have a question and then a
Could you tell us if you have any clues in the case of the death of Ms. Nguyen as to how she was exposed, any advances?
DR. PERKINS: We do not have any good clues to date. And her exposure, resulting in inhalational anthrax remains enigmatic at this point, and
it's an extremely high priority of the investigation in New York City to try to better clarify the circumstances that she was exposed to
Bacillus anthracis spores.
QUESTION: Is it at all helpful, as you said yesterday, that you found that it was virtually indistinguishable from the Daschle letter? Does that
help the investigation at all?
DR. PERKINS: I think that that's important information, particularly in regard to treatment of individuals that she was around and may have also
been exposed. In regard to the antimicrobial susceptibilities of this organism, we're confident, based on those data, that those people,
particularly her coworkers at the hospital, are being treated with the right antibiotic to prevent development of inhalational anthrax.
AT&T MODERATOR: Thank you. Our next question is from the line of Robert Bazell [ph] with NBC News. Please go ahead.
QUESTION: To follow up on the question before about the New York case, what is the quality of the environmental samples that have been done? Was
it the culture samples that you just described or was it some sort of instant samples in which you are less confident; in other words, what's
your confidence in the environmental sampling that's been done so far in the New York case, the inhalational anthrax case?
I have a follow-up.
DR. PERKINS: They've been using a two-step procedure for testing of environmental samples in New York City. In order to expedite the
availability of results, they have been applying a PCR technology that you can do essentially within hours after collecting the sample. This is
a technology that allows for the direct detection of Bacillus anthracis DNA, and results from that testing are considered preliminary.
At the same time they were running those DNA tests, the samples were put on culture plates. That takes a longer time, at least 24 hours before
it is possible to read them out as negatives. But they've been using this two-tiered process.
Again, we consider the gold standard for environmental sampling to be culturing environmental samples on plates and waiting for the organism to
QUESTION: I have a follow-up question then.
Do you have any evidence, at this point, that that patient was in some area where somebody else has either a confirmed or a highly suspect case
of cutaneous anthrax at the same time?
DR. PERKINS: We are actively doing very aggressive monitoring or surveillance of persons that were in environments that were shared by this
patient. We do not have any suspect or confirmed cases of either cutaneous or inhalational anthrax that we know shared environments that she had
AT&T MODERATOR: Thank you. Our next question is from Susan Ferraro with the New York Daily News. Please go ahead.
QUESTION: Good morning, Dr. Perkins. Thank you very much again, on my part, and I'm sure everyone's, for having these briefings.
The woman who died in New York, how far are you extending your additional environmental tests to track her movements?
DR. PERKINS: Environmental testing is being extended to, at this point, is being extended to everywhere that we can identify that she had been
in the last 2 weeks, and local health officials, along with CDC officials, are working with FBI to try to develop as complete a picture as
possible about all of her activities and locations she may have been over the last 2 weeks.
It's unfortunate that there are not more people available to public health and other officials about exactly all of the things she may have
done, but we are following absolutely every clue we can find about what she's been doing over the last 2 weeks prior to development of illness.
AT&T MODERATOR: Thank you. Our next question is from Kayoshi Endo with the Nikkai [ph] Newspaper. Please go ahead.
QUESTION: Thank you.
Given that there is no other cases, even though there was a mysterious case in New York, given that there is no additional case, do you think
the worst is over in New York?
I think in Washington health officials are saying we may have already passed the worst point already, and given that there is no additional
cases in New York, even though there is that special case, Ms. Nguyen, do you think the worst may be over now?
DR. PERKINS: In many of the situations that public health officials are called upon to deal with, we're confronted with biologic phenomenon that
are explainable in terms of the course of outbreaks or epidemics. This is quite different, and this is a criminal activity that public health
officials cannot anticipate.
So we remain extremely vigilant about the occurrence of additional cases associated with the mail system or additional cases that may not be
associated with the mail system. And I think it's a very important point to recognize that this is not a normal epidemic resulting from
predictable biologic phenomenon. This is a criminal activity. We will remain on high alert, high vigilance until the criminal investigation has
identified the people that are committing this crime.
AT&T MODERATOR: Thank you. Our next question is from the line of David Brown with the Washington Post. Please go ahead.
QUESTION: Yes, Dr. Perkins, is CDC sending any environmental samplers to places where there have been no cases and swabbing to see if there is,
in fact, a background of anthrax spores and that that might explain the detection of one spore in a couple of places?
DR. PERKINS: CDC is not recommending or performing environmental sampling in environments that are not linked with the ongoing investigation. We
do recognize that, as a result of cross-contamination events that occurred in the context of known or other suspected letters, that there may be
some increasing level of environmental contamination in a variety of locations. To date, those levels of contamination in those locations that
we're hearing about that have some environmental contamination have not been associated with human disease. That's a situation that we're, of
course, following very carefully.
Again we know of environment in the United States and elsewhere where there is a normal level of background contamination with Bacillus
anthraces spores, and people do not get disease.
Texas recently had an epizootic, an epidemic of anthrax in cattle, you know, that resulted from ground contamination with Bacillus anthraces
spores. So we know that it's out in the environment in many locations where humans do not get sick.
AT&T MODERATOR: Thank you. Our next question is from Alice Park with Time Magazine. Please go ahead.
QUESTION: Good afternoon. I actually have two related questions. The first being you referred to the additional tests being done. Can you detail
for us as an epidemiological problem, are you looking at the possibility of spores re-aerosolizing into something like a piece of paper or an
envelope and how likely that is, and what kind of concentration you might get from a situation like that? And I'm talking here obviously, you
know, as part of a, you know, a research or a scientific study.
And secondly, can you at this point make any guesses as to whether we're talking here about really cross-contamination or the potential of an
DR. PERKINS: Right. That's a good question. We are obviously most concerned about aerosolization situations in terms of the risks they convey
for inhalational anthrax.
There is a great deal of research that's been done in this area within the context of defense-oriented programs and we are working to take every
advantage of that research, especially in terms of risk for re-aerosolization. That's a critical--I mean the interpretation of re-aerosolization
risk is a critical node in our development of a public health response to the situations we are seeing. And we are considering additional
studies, you know, potentially evaluating the risk for re-aerosolization around automated sorting machinery in post office settings.
We think that that risk, based on earlier data, is probably quite low, and that when a contaminated letter comes through those sort of settings
that there is an aerosol risk that occurs, and that that risk is time-limited, and that would be the hypothesis most consistent with research
that's been done.
We would like, however, to get additional data about the re-aerosolization risk around postal sorting machines.
AT&T MODERATOR: Thank you. Our next question is from the line of Robert Schlesinger with The Boston Globe. Please go ahead.
QUESTION: Yes, Doctor, in the reports of an anthrax letter sent to a newspaper in Pakistan, are you all going to do anything? What are you doing
to cooperate or exchange information with the Pakistani government? And are you sending samples over or getting them there to see if there's any
DR. PERKINS: Here in the emergency operations center at CDC, we are responding to this investigation. We have a very active international
activity that's responding to the situation in Pakistan as well as a number of other situations of concern around the world. And we are
providing support in those situations on all kinds of different levels.
In the case of the Pakistan incident, we've provided technical support over the phone to laboratorians involved with evaluation of bacteria in
that situation. In some circumstances people are sending suspect bacterial strains to CDC for further identification.
We have got epidemiologists consulting with other epidemiologists in foreign countries. So that's quite an active area of emergency operations
support here at CDC.
AT&T MODERATOR: Thank you. We have a question from the line of Jeremy Manier with The Chicago Tribune. Please go ahead.
QUESTION: Thanks very much. Doctor, are the PCR tests that can be used for anthrax, are those available to ordinary people in the hospitals, or
is that something that's limited to the CDC and state laboratories?
DR. PERKINS: These are--the PCR tests that are being used within the laboratory response network for bioterrorism are tests that have just been
developed here at CDC in collaboration with other partners in the defense arena, and they are not widely available outside of the laboratory
response network at this point.
They have, certainly in the hands of CDC during this epidemiologic investigation, have performed admirably, and I think that as we move forward,
a broader dissemination of this kind of technology to other laboratories will become a priority.
AT&T MODERATOR: Thank you. Our next question is from Ellen Beck with United Press International. Please go ahead.
QUESTION: Yes. Thank you. Good afternoon. I was wondering, FBI Director Mueller today said that they had not got as many leads or tips from the
$1 million reward as they had expected, and he again asked the public to take another look at their surroundings and the people they're with,
and those letters that were sent to see if they could give any more tips or leads.
My question is aside from another major incident of anthrax coming up to our attention, aside from perhaps another letter, how close are we to
the point of where you say perhaps we just will never know who sent this?
DR. PERKINS: I hope that we're not close to that point, and we continue to work very actively with the FBI, both at local levels and at their
headquarters in Washington, to freely interchange information to help them develop new leads for investigation.
I do not think we are at the point of suggesting that we're ready to give up, and I think that that remains the highest priority of all of our
efforts, is to identify who is doing this and to stop them.
AT&T MODERATOR: Thank you. We have a question from Steven Russell with the San Francisco Chronicle. Please go ahead.
QUESTION: Hello, Dr. Perkins. I have a question about the median age of the cases so far being 56. It seems to be that older people may be at
slighter higher risk? Do you have any comment? Can you read anything into this or are we any closer to developing a risk profile of who might be
more at risk for inhalational anthrax under these circumstances?
DR. PERKINS: I think that that's a very valid observation and one that we've been watching carefully here at CDC. The age distribution among the
inhalational cases seems to be slightly out of step with the occupational age distribution that you would expect among the folks that look like
they're at risk, suggesting that there may be host factors or particular susceptibilities in persons that might be a little bit older. And we're
actively exploring that as a hypothesis based on the ten cases that we have.
I think leading hypotheses would be issues surrounding the mechanical clearance of things like bacterial spores when they get into the
respiratory system. Certainly there are data that suggests that smoking damages the normal clearance mechanisms and that among older age
persons, especially those who smoke, the damage of those clearance mechanisms may allow infections like Bacillus anthracis to get a foothold and
to cause disease more frequently in those kinds of settings.
So I think it's an important observation. It's something we're following carefully, and I'm going to try to develop clear explanations why that
might be occurring.
AT&T MODERATOR: Thank you. Our next question is from Rick Weiss with the Washington Post. Please go ahead.
QUESTION: I also had a question about host factors that maybe you just answered that, but I wonder specifically if you could say anything about
whether you have yet drawn any correlations between any host-risk factors, such as smoking, with the incidence of disease in the victims so far?
Separately, could you say anything about rumors that some of us have heard about the appearance of a possible smallpox case somewhere in the
DR. PERKINS: Certainly, I am not aware of any reported smallpox case someplace else in the world.
We, basically, our priority here on the clinical evaluation side at CDC, and we have a large group working very intensively both at the field
level and here at CDC to characterize the clinical presentation. The priority has been, number one, making sure that we were making the absolute
best recommendations we could for treatment of these individuals; and, number two, trying to characterize the clinical presentation of these
first ten cases to help physicians out there on the front lines recognize these cases if they presented before them.
I think now, as we've gotten that information together and I think started to get that information out and available, we're starting to look at
some of the issues regarding host factors. I think over the next several days that's going to become a focus of the clinical team's activities
here at CDC.
AT&T MODERATOR: Thank you. Our next question is from Aaron McWilliam with the Associated Press. Please go ahead.
QUESTION: I had a couple of questions, if that's okay.
First of all, has there been any further progress or any decision on whether to vaccinate those 800 laboratory response network workers?
And, secondly, I was wondering if there's any other place--you mentioned Arizona--where you're sending epidemiologists protectively as sort of a
DR. PERKINS: The second question first. We are sensitive to the needs of state and local health officials to conduct especially intensive
surveillance around special events like the World Series, and that is the reason that epidemiologists went to Arizona. There is the same
sensitivity, obviously, in New York City, where they have had intensive surveillance established and ongoing since the events of 9/11.
I'm sorry. The other question you asked?
QUESTION: I was asking about those laboratory response network workers.
DR. PERKINS: Oh, yes. We are actively working with our Advisory Committee on immunization practices, the body that makes vaccine recommendations
along with CDC at the national level, to clarify groups that should be considered priorities for vaccination in view of the recent
epidemiological events. And we think that the laboratorians working in the laboratory response network for bioterrorism are a group that should
be prioritized for vaccination.
These are people that are now receiving environmental specimens, particularly powders that may contain, based on our recent experience, very
high levels of Bacillus anthracis spore contamination. Because we feel that the risk is real, that they may be exposed to these things, we would
like to see them vaccinated.
I would point out that this falls--their vaccination falls within the realm of already made ACIP guidelines in regard to use of the anthrax
vaccine, and what has changed is their risk, as a result of recent events. So I don't think this sets any new precedent for use of vaccine in
the United States.
AT&T MODERATOR: Thank you. Our next question is from Mary Manning with the Las Vegas Sun. Please go ahead.
QUESTION: It's Mary Manning, Dr. Perkins, and good afternoon, and thanks for having these conferences.
My question is, in the autopsies of the four individuals who have died, has there been any attempt to measure the size of the particles in the
DR. PERKINS: That's an interesting question. I don't think that that is possible because those particles get essentially metabolized or handled
by the body's defense systems or barriers, if you will, and so the body breaks those powders down into components that, you know, including the
spore which is transferred to the lymph nodes and then germinate and replicate to very high numbers.
We are interested in better characterization of powders associated with these events because it is an important part of determining what the
risk is for inhalational disease, but our efforts in that regard have focused on the powder contained in suspect or confirmed envelopes, and the
potential to evaluate powder that is spread in the environment, that hasn't been faced with degeneration within the human body, and we think
that there may be some things that we can do in that regard. But, actually, within the body, we don't think that that's likely to be very
AT&T MODERATOR: Thank you. We have a question from Monica Conrad with ABC News. Please go ahead.
QUESTION: Hi. I've got a couple of questions.
In addition to the lab workers that you want vaccinated, what are the discussions about Postal workers and HAZMAT crews? Who else are you
putting into that group that should be vaccinated or considering?
DR. PERKINS: We have active discussions here at CDC and with the Advisory Committee on Immunization Practices about who we think is at highest
risk of disease. The groups that we're most concerned about at this point are people that we think are repeatedly exposed to environmental
samples or potentially contaminated letters that contain Bacillus anthracis spores, and we're using the ongoing investigations to help us
identify and clarify who falls into that group and how big that population is.
Those are fundamental pieces of information that we will use to try to help develop policy about use of the very limited supply of vaccine now
and how we approach potentially increasing available supplies of vaccine.
QUESTION: Just a few more specific questions.
When do you think those decisions will be made regarding the universe that would get the vaccine or recommended to get the vaccine?
DR. PERKINS: I really don't know when those decisions will be made. That's sort out of my hands. I can tell you that it is the subject of
ongoing intensive discussion at a variety of levels within the Federal government, both within HHS and outside.
QUESTION: Okay. And just--you mentioned two other things, if I could have clarification. In addition to Pakistan, you said there are other
countries you are consulting with. Can you tell us what those countries?
DR. PERKINS: I mean there are a number of countries. I don't know what our position is on releasing all of that. Yeah. I'm not in a position
actually to comment on the number of countries, just other than to say that I mean it's been--we have seen a number of anthrax hoaxes on an
international level in association with the outbreaks here in the United States.
CDC MODERATOR: Thank you. John, we have time for one more question.
AT&T MODERATOR: And that will be from the line of David Koon with Uelma Area Newspapers. Please go ahead.
QUESTION: Hi. Thanks again for having these.
Tom Ridge, of course, said that this was from the Ames family or the Ames strain exactly. Do you know which it is? Is this the strain from--that
we saw in the 1950s in the USDA in Iowa, specifically?
DR. PERKINS: We have used molecular subtyping in the context of this investigation to help clarify how environmental isolates and clinical
isolates from the various investigations are related to each other. I think--and that's important for terms of epidemiology, and obviously we
have a great deal of interest in the antimicrobial susceptibilities.
I think trying to extrapolate further than that in terms of the origins of this strain are beyond, you know, direct interest of public health
authorities in this situation, and but the FBI is, of course, you know, very interested in those things, and I think that lies sort of more in
the realm of criminal investigation, and I'm not going to comment any further on that.
CDC MODERATOR: Okay. Thank you, ladies and gentlemen. That concludes our telebriefing for today. The next telebriefing will be on Monday. Thank
AT&T MODERATOR: And, ladies and gentlemen, that does conclude your conference for today. We thank you for your participation and you may now