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Update on Anthrax Investigations
with Dr. Julie Gerberding
November 15, 2001
CDC MODERATOR: Good afternoon. Today, our speaker is Dr. Julie Gerberding. She'll discuss the update on anthrax investigations in the MMWR.
The main article discussed anthrax in the United States and other countries, and also there's a notice to readers that's treatment for children
and for pregnant women.
DR. GERBERDING: Thank you.
The MMWR today does give a brief update on the evolving anthrax investigation. As you know, we've had no new cases in the last several days. All
of the individuals who had been in the hospital with anthrax are now discharged, and are doing well at home. So that's the good news
What we have emphasized in this particular MMWR is the importance of adherence to the 60-day prophylaxis regimen for people who have been
exposed to airborne B. anthracis. We recognize that we started a very large number of people on antimicrobial therapy initially, and as
investigations provided more information about who actually was at risk for airborne exposure, the circle of people who need to be treated has
narrowed substantially, but now the emphasis is really honing in on those people who were exposed because they are still at ongoing risk for
developing anthrax, if they do not complete their antibiotic therapy.
Experience with a variety of other medical illnesses provides us some pretty strong basis for being concerned about individual's capacity to
adhere to an antibiotic regimen for the full 60 days.
In this issue we've defined three groups of people who are at high risk for developing inhalation anthrax without prophylaxis. Those include
people who shared air in the same environment with someone who is a case of anthrax, individuals who were exposed to aerosolized powders, for
example, those in the Senate office building where the envelope was opened, or those who have worked with equipment or machinery, or in
environments where an aerosolized, where a letter that may produce an aerosol has been, traveled. So this would include postal workers who work
around sorting machines or in environments where the air from the sorting machine presents shared air space with co-workers.
These individuals have been identified, they are on antibiotic therapy now. They're at various stages of treatment. Some of them are being
brought back in for their refills, and so forth, and CDC is working hard with the postal authorities, the labor and management groups, as well
as the state and local health departments involved in these areas, to do everything possible to promote adherence to the antibiotic regimen.
Some of the activities that we are involved in address the things that we know from work in other patient populations might help adherence. That
includes simply providing information about the importance of treatment as well as how to manage the side effects from treatment, as well as
more detailed information to help people understand their risk and to put it into context, and then, finally, supporting adherence through peer
counseling, advocates, that individuals might regard as respected or trusted opinion leaders, and offering them access to additional
consultation or input through Warm [?] lines or contacts with the CDC, and other external advisory groups.
So these efforts are underway. I just came from a meeting where some of the details of the activities at specific sites are being pinned down
and we intend to do everything we can, as a federal agency, to support the adherence among individuals who, again, we perceive to be at risk for
this infection, if they are unable to complete their full day 60-day regimen.
So let me stop there and I'm happy to take any questions.
AT&T MODERATOR: And ladies and gentlemen, once again, if you do have a question at this time please press the one on your touchtone phone.
You'll hear a tone indicating you've been placed in queue. You may remove yourself from queue at any time by pressing the pound key. Once again,
if you have a question, please press the one.
Our first question is from the line of Sho Beppu [ph] with BHK Japan. Please go ahead.
QUESTION: Yes. Good afternoon, Doctor. I have three questions. The first question is about terminology. Nowadays, we talk a lot about cross
contamination. Could you define this word, cross contamination.
My second question is about Mrs. Nguyen's case in Manhattan. So far what have you been doing, in what many places of the environment, tests have
been done in the subway?
The third question is related to the second one. What kind of investigation has been done in Chinatown? I am asking these two questions because
when I talked to the local people, they were quite anxious to know more about what is going on, to better, have a better understanding of the
situation. Thank you very much.
DR. GERBERDING: Thank you.
With respect to the concept of cross contamination, we haven't defined a full term of reference here, but generally what we are referring to is
a situation where a envelope containing a anthrax powder has allowed adjacent envelopes, or adjacent components of the environment to pick up
some of the spores, so that they are contaminated, not because the anthrax was originally put there, but because they were located either next
to the contaminated envelope or because somehow the anthrax was mechanically moved from the source to sort of an innocent bystander material.
With respect to the status of the investigation and the evaluation in New York City, that investigation is still ongoing. Certain components of
the subway system have been sampled for the presence of anthrax. Those results are not available and will not be available until enough time has
gone by to ensure that absolutely nothing is gonna grow on the plate. So we have no information about the results of the subway sampling at this
time, and in terms of what's being done in Chinatown, at the moment, my understanding is the New York City Health Department, in consultation
with others, including the FBI and CDC, is planning to continue to evaluate known personal contacts of the hospital worker with inhalation
anthrax, and would not initiate additional environmental sampling unless there was a presumptive reason to suspect that a particular environment
had been the location of a source of exposure.
CDC MODERATOR: Next question, please.
AT&T MODERATOR: Thank you. That's from the line of Erin MacLean with the Associated Press. Please go ahead.
QUESTION: Hi. I have two questions out of the MMWR today, if that's all right. The first, on that list of people who need to adhere to the
60-day prophylactic treatment, do you have a sense of how many of those people are actually taking the drugs? Have you been able to reach all of
them and are you concerned that some of them have started the treatment and have stopped taking the drugs?
DR. GERBERDING: No, we have information in various stages of evolution because the different sites are in various stages of their treatment. But
we are assessing adherence right now through a couple of means.
One is sort of the default. As people are coming back for their medication, there is some assumption that they're taking it, although that isn't
necessarily true. They may come back to receive it and not take it.
But in addition we have a process of self-reported evaluation of the adherence to the regimen, and we are working with scientists at the
University of California, the NIH and other places to help us use the same standards for evaluating adherence as we might use in other
populations such as patients with HIV infection or patients with hypertension.
So we are using tools that have been successful in other groups to try to evaluate adherence and, then, second, to promote adherence.
The exact estimate of what the current level of adherence is varies from group to group. In some of the environments where we have already done
some initial assessments, it's quite good.
For example, at the AMI building, the initial assessment of adherence there was that it was above 80 percent, and that's without contacting
people by phone or doing any supplemental intervention.
AT&T MODERATOR: Our next question is from [inaudible] with Global Radio News. Please go ahead.
QUESTION: Two questions, if possible. First, in the MMWR, you report that 15 nations have received laboratory assistance, including testing or
arrangements for testing of suspected isolates. Are these totally from Central and South America, or are there some European or possibly African
nations included in the list of 15?
And second, the Miami Herald today reported that several Federal officials are leaning toward a lone nut source for the anthrax outbreak. Do you
have any comment or reaction on that story?
DR. GERBERDING: With respect to your initial question about what--where are the countries that have requested laboratory assistance, most of
these countries are from Africa, South America, and some parts of Asia. However, we have received a smattering of requests from a variety of
other places as well, and I can't tell you the specific breakdown on this call because I don't have the details in front of me.
With the theory that's been promoted about the perpetrator of this biological attack, I have heard several theories over the last several weeks.
I think CDC is not focusing on that particular aspect of the investigation. That's really the FBI's domain, and we respect whatever theories or
evidence they can put forward to help lead to prosecution of the criminal.
AT&T MODERATOR: Our next question is from David Routh with the National Journal Group. Please go ahead.
QUESTION: Hi. My question is, is the CDC's recommendation for administering antibiotics in any way linked to the levels of anthrax spores found?
Sort of asked another way, do you have a threshold for the fatal dosage that you're sort of looking at?
DR. GERBERDING: We do not have a precise threshold. We have made the decision that if our evaluation of the environment or of the exposure event
or of the nasal swabs of people if we were doing nasal swabs close to the point in time and we thought a source had been present in the
environment, if any of those evaluations indicate that there was detectable airborne anthrax in the breathing zones of people, we were
considering them to be at risk and recommending the 60-day treatment course.
If, on the other hand, we go in and do surface samples of environments where there hasn't been a case of inhalation anthrax or there hasn't been
a powder go through a situation where we recognize the potential for aerosolization and the degree of contamination is trace or, you know, one
out of 20 samples are positive, or we only see white growth when we do sample, we would not recommend people in those kinds of environments to
receive the 60-day regimen because we have no epidemiologic or scientific evidence that that particular finding poses a risk.
AT&T MODERATOR: Our next question is from Shawn Verdunkin with The Washington Post. Please go ahead.
QUESTION: Hi. Thank you to the CDC for doing these briefings. They're really helpful. I hope you will continue doing them.
I have a few questions, the first about the 60-day regimen. How many people in all are on the 60-day regimen? What antibiotics are they taking?
And what side effects are you seeing? And I have a follow-up question unrelated to this.
DR. GERBERDING: With respect to the exact number on the 60-day regimen, I'll have to get back to you on that because I don't have that number in
front of me and it varies from one geography to another.
In addition to the six groups that were highlighted in the MMWR, there are handfuls of people here and there who are in special situations where
we are also recommending 60 days, and I haven't tallied those up.
What was your second question?
QUESTION: What are the antibiotics and what side effects are you seeing?
DR. GERBERDING: Most of the people currently are on doxycycline. The major side effect that we are observing is the gastrointestinal side
effect. That's a known complication of doxycycline therapy, nausea, upset stomach, maybe a little diarrhea. So these are expected and known
complications of that particular medication, and it can be improved by things like antibiotics with water and not laying down after you've taken
it and so forth.
So one of the things that we created over the weekend was an updated set of information for people on these regimens to help them understand
better not only what the side effects might be but some of the simple things they can do to help manage their side effects and tolerate the
QUESTION: Where does the 60-day regimen come from? I know the FDA sort of put that into effect, and there were concerns after the Sverdlask
incident in 1979 in Russia where people felt sick weeks and weeks after the fact. But given that we've had so little experience with anthrax
until the current outbreak, are you being sort of more cautious and conservative to sort of err on the safe side?
DR. GERBERDING: There are two pieces of evidence that support the need for a long-term prophylactic regimen. One piece of evidence is from the
experience in the outbreak that occurred involving people who developed disease up to 42 days after the release from the plant where the anthrax
was being manufactured.
However, there are also animal data that indicate if you only treat animals after an exposure for 30 days, some of the animals will go on to
develop anthrax in the few days after that. So it's important, in our mind, to kind of put these two pieces of data together and make sure that
we've covered people for the period of time where we're giving the maximum benefit.
It's true that most of the benefit from the treatment probably is with the initial course of antibiotics, but this is such a serious disease
that it makes sense to err on the side of completing the full 60 days.
AT&T MODERATOR: Thank you. Our next question is from Kim Dixon with Bloomberg News. Please go ahead.
QUESTION: Hi. Thanks. You said from experience you were concerned about adherence from experience with other illnesses. Could you give an
example of some adherence statistics? And also what's the low end? You said on the high end, people at AMI, about 80 percent are taking it. Do
you have a low estimate?
And finally, on the animal studies that you just talked about, you said some people do go on to develop anthrax after 30 days. Do you know just
roughly what percentage of people?
DR. GERBERDING: The first question, with respect to analogy about adherence for a variety of conditions is highly variable. My own experience
would pertain to post-exposure prophylaxis after occupational needle sticks involving HIV in and among health care workers who were
knowledgeable about the risk and knowledgeable about the disease. We generally would see adherence somewhere around 60 to 65 percent.
There are other data in other groups of people taking post-exposure prophylaxis to prevent HIV for community exposures where adherence rates are
better, sometimes as high as 80 to 85 percent. So that gives you some range of post-exposure prophylaxis situations of what the data are, and it
certainly indicates that adherence is not 100 percent.
So in this case we are working hard to try to get as close to 100 percent as we can.
The low end of adherence is something that I can't answer yet because we haven't completed the evaluation. One of the concerns we have is more
time goes by, people tend to become less adherent, over time. So as we move into the period where people have already taken 30 days of
medication, we may see a decline in their capacity to take their medicines twice a day. That's exactly why we're being as proactive as we can to
support that through to the end of treatment.
And then, finally, your question about the cases after 30 days, that, I was speaking of animal data. These are nonhuman primates that were
involved in experiments, that may or may not have anything to do with the kinds of inhalation exposures we're dealing with among people.
So I said that the data suggests there can be late cases, if the prophylactic treatment isn't continued for a long period of time in those
AT&T MODERATOR: Thank you. Our next question is from Emma Hitt with Reuters Health. Please go ahead.
QUESTION: Yes. Hi. I was interested in the notice to readers about the children and breast-feeding mothers. Can you just give some kind of main
message that you'd like to get out to physicians about feeding children and breast-feeding mothers, and also can you address the issue of the
use of Amoxicillin with the strains that are susceptible, that have betalactomize [?] activity.
DR. GERBERDING: If a breast-feeding woman is exposed to airborne B. anthracis, it is important that the breast-feeding woman participate in the
post-exposure prophylactic treatment regimen, the same way as anybody in that exposure situation would need to do. The safety concerns for the
developing fetus have to be balanced against the importance of the treatment to protect both the mother and the baby, because we recognize that
we have less information about the safety of Fluoroquinalones and we recognize some toxicity's associated with Tetracycline use during
pregnancy. Finding safer alternatives is a priority.
In this particular cluster of cases associated with this strain of B. anthracis that we're dealing with, we have had medical experts and
microbiologists evaluate the organism, and we believe that it is susceptible to Amoxicillin if we don't have a high tider [ph] like we would in
someone who actually had infection.
So for prevention of illness, Amoxicillin is a good option for those people unable to take Ciprofloxacin or Doxycycline.
CDC MODERATOR: Next question, please.
AT&T MODERATOR: Thank you. That's from Mary McKenna with the Atlanta Journal. Please go ahead.
QUESTION: Hi. Thanks for doing these briefings. Most of my questions have been asked already but I've a couple of others.
Could you define, more precisely, where the information is coming from that, about side effects among people who are taking the prophylaxis, and
also about concerns about adherence.
Is it from the health departments? Is it from private clinicians? Or is it, in the case of adherence, is it an assumption based on other
populations in which you've observed post-exposure prophylaxis such as health care workers and needle sticks?
DR. GERBERDING: Information about the side effects and adherence in these settings is coming from the people who are taking the drugs, and this
is being assessed when they come back for their refills or when they're called on the phone to find out why they didn't come back for their
refills. We've also conducted, in some of the locations, focus groups.
For example, we finished some focus groups yesterday at one of the sites with workers who are taking the treatment, who understand what they're
experiencing, how they're managing, what's helpful in promoting adherence, what isn't working.
So we're using all sources of information but the primary source are the individuals who are taking the treatment, and they're reporting that
both verbally as well as on standardized forms that are completed when they return to receive their next supply of drugs.
AT&T MODERATOR: Our next question is from the line of Ellen Beck with United Press International. Please go ahead.
QUESTION: Yes. Thank you very much.
The companies and various agencies downstream Brentwood and perhaps those involved in New Jersey, that are doing their own cleanup and their own
testing, are you keeping track of them or are you requiring them to do any reporting back to you as far as their success and what they've been
DR. GERBERDING: CDC has no authority to require any reporting to us. However, we're certainly providing consultation and we're interested in the
results, and to the extent that the testing is completed and we're able to track down the information, we're working on compiling the data that
we do have available to us.
In some cases, downstream postal mailroom facilities prefer to keep the information within their own corporate environment and we have no
authority to compel them to disclose it.
Our sense is the vast majority of these sites have negative cultures. Many others are likely to still be in progress in their evaluation because
some of the laboratories that they're using can only do the preliminary testing, and then the samples have to go to a different laboratory that
can do the more sophisticated test. So it's taking some time to get all the information together.
CDC MODERATOR: Next question, please.
AT&T MODERATOR: Thank you. That's from Charles Seabrook with the Atlanta News. Please go ahead.
QUESTION: Dr. Gerberding, I don't know if you can answer this or not, but I was trying to take another look at the cleanup efforts, and there's
some folks who say that some of the spores will never be completely removed from a building. That others say, well, [inaudible] and so forth.
Could you address that at all.
DR. GERBERDING: The thing is that we have to use a little common sense here. We don't live in sterile households. We don't work in sterile
buildings. Our environment is full of bacteria and some of them are pathogens in the right circumstances.
I don't think our goal is to eradicate every single B. anthracis spore from any particular environment. Our goal is to ensure that environments
are safe for people and that there is not a health risk associated with the level of contamination that might be present.
So I'm not aware of anyone with, anyone involved in these decontamination efforts indicating that the goal is to eliminate or eradicate every
single anthrax spore that might be present. I think all of us share the goal of making these environments safe.
CDC MODERATOR: Next question, please.
AT&T MODERATOR: Thank you. That's from Lauren Nergard [ph] with the Associated Press. Please go ahead.
QUESTION: Just a couple questions, first, to follow up on the previous question. Do you have an actual goal of how many spores would be that
sort of safe environmental level? Looking at the side effects issue, can you tell us how many, if any, of the serious side effects that are
known, associated with Cipro, have been spotted, any of the CNS problems or tendon ruptures?
And I was a little intrigued, looking at your comments surrounding the 7-month-old case in your notice to readers in MMWR today.
How sick was that baby? How much systemic disease did he have, and what does that tell you about any risk for other children?
And I wonder also when in the course--was he really infected? Did he become sick a day or two after just visiting that building, or did it
happen that fast or could his mother have actually brought spores home on her clothing from the building and whatever letter entered that
DR. GERBERDING: Let me start with the issue of the spore count. What we can say at this point in time is that we are very confident we
understand the extremes. If there are a few spores, and by that I mean we can find on a plate that has been created from a swab covering a large
area of surface, one or two colonies, or of all the plates that we sample in a particular environment we find only one or two that contain trace
amounts of anthrax, we consider that to be trace contamination and we have no evidence that that poses any kind of a health risk whatsoever.
At the opposite extreme, when we find widespread environmental contamination, i.e., many plates are positive, or the plates are growing heavy
growth of numerous colonies as a bacteria, that's strongly suggestive of airborne contamination or widespread surface contamination, and
obviously our data indicate that's a health risk.
In between those two extremes, the cutoff has not been defined, and we are working with experts on risk assessment and evaluation of
environmental safety, to try to see if we can provide any more specificity around these estimates.
For now, because we don't have a threshold, when we see anything beyond trace contamination, we're erring on the side of decontaminating the
environment and assessing for aerosol risk and treating people accordingly.
With respect to your question about serious side effects with Ciprofloxacin, currently, most of the people we're treating are on Doxycycline and
the assessment of the Cipro toxicity has initially, there were some reports of very serious adverse events, but when we've gone back and
reviewed the charts, as we reported in last week's MMWR, we are not finding those serious adverse events and we are not finding adverse events
to be attributable to the drug.
So while it certainly doesn't rule out that possibility and as more information becomes available, we're putting a high priority on
investigating such reports.
We know that those side effects can occur because the FDA has collected that information through the years, but we're not being surprised by
anything in this experience. What we're seeing is what we expected to see based on what is already known about the drug.
With respect to the small child who is mentioned in the MMWR, this child was hospitalized with the cutaneous form of anthrax but had evidence of
surrounding tissue infection and swelling, and was systemically ill for a few days until the antibiotics were effective, and I would have to
refer any additional questions for information about those details to the health department in New York City.
We cannot precisely determine where the child was infected but the epidemiologic information strongly suggests that the workplace was the source
of the exposure that led to the illness.
CDC MODERATOR: Next question, please.
AT&T MODERATOR: Thank you, and that's a follow-up from Erin MacLean with the Associated Press. Please go ahead.
QUESTION: Yeah. Hi. Thank you for taking another question. Just one tiny little question on this antibiotic therapy.
I know you're concerned that some people that prescribe this regimen and aren't sticking to 60 days, but are you concerned there are people who
are falling into these groups who may have been exposed that you haven't reached at all yet?
DR. GERBERDING: Our field teams involved in the various locations have worked very hard with the managers in the labor organizations and others
who are able to ascertain who the employees were at risk, or who the visitors were to certain of the locales, and who the other visitors were.
So we are looking to cast a broad net and make sure that we have not missed any groups.
Our experience so far suggests that we must be on the right track because we haven't seen cases of inhalation anthrax in people who have been
missed as a consequence of our efforts.
So it's always possible, but we think we've cast a broad net and have identified individuals who are truly at risk for inhalation exposure.
CDC MODERATOR: Next question.
AT&T MODERATOR: Thank you, and that's a follow-up from Sho Banpu with PHK Japan. Please go ahead.
QUESTION: Yes. Once again, it's always about this Green Line case with the subway testing. Could you give us an idea about the place, the date,
and the number of samples that were taken from the subway? I'm asking this question because my viewers are quite interested in something that
happens in subways.
DR. GERBERDING: I understand there's a great deal of interest in the evaluation of the subway in New York, and the team that had the lead for
that evaluation is New York City Health Department in conjunction with others, and so information about the subway sampling and the results will
be available from them when the results are known.
CDC MODERATOR: Next question.
AT&T MODERATOR: And that's a follow-up from Shawn Covernance with Washington Post. Please go ahead.
QUESTION: Hi. Could you talk about treatment regimens for pregnant women and small children?
DR. GERBERDING: The NMWR published some initial guidance for treatment of both pregnant women and small children, and I assume you're referring
to treatment of disease. Is that correct? Or prophylaxis to prevent infection?
Well, let me just assume that you mean treatment of anthrax disease.
The guidelines for initial therapy for pregnant women and children are the same as they are for adults, and that is that you would start with a
child or pregnant woman with inhalation anthrax, you would use a combination regimen that would include Ciprofloxicin or Doxycycline as well as
one or two other drugs that are--to which the organism is susceptible. And once clinical improvement was noted, then you would switch to an oral
regiment, for the long term completion of the 60 days of therapy could safely do that with amoxicillin or a similar drug that is less risky in
CDC MODERATOR: We have time for one more question.
AT&T MODERATOR: Actually, Ms. Hoskins, no further questions. Thank you.
CDC MODERATOR: Okay. Well, thank you for participating in this telebriefing, and a transcript will be available on line later today.
AT&T MODERATOR: And, ladies and gentlemen, that does conclude your conference for today. We thank you for your participation and you may now