Webcast Transcript

Anthrax: What Every Clinician Should Know, Part 1

(October 18, 2001)

(View the webcast on the University of North Carolina School of Public Health site.)

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Dr. Baker (moderator):
Brad, let’s turn back to this case definition if we could for a minute. This is a real important part of our program today because obviously our desire is to have clinicians out there report to their local or state health department if a case occurs. So maybe we can go over that again.

In the anthrax case definition you mentioned that culture or other laboratory tests that could be used to confirm an anthrax case. Could you tell us then some more about how clinicians can get this testing on a suspect case? How is that available?

Dr. Perkins:
Well, again, I think this is a very important area. The case definitions I presented earlier are designed to reflect various levels of diagnostic certainty in patients with clinically consistent illness either with or without known exposure to Bacillus anthracis. We would like to see culture isolation from all of these because we feel that that’s the gold standard for diagnosis, but that is not possible in all circumstances and we are fortunate to have a variety of other laboratory tools that will allow us to confirm cases of disease. In the routine clinical setting it is possible to get a fair ways down the road in terms of diagnosis of anthrax disease in just the regular clinical microbiology laboratory. Again, this organism grows phenomenally well on routine sheep blood agar plates that are used in essentially all clinical laboratories. It is easy to get the bacillus level identification, and at that level any bacillus species that is nonmotile, nonhemolytic that is growing under aerobic conditions should be quite suspicious in a setting of clinically consistent illness. And actually even that level of diagnostic confirmation should trigger a report to the public health system.

What’s difficult is when you get beyond that. It is actually quite challenging to distinguish many of the other bacillus species from Bacillus anthracis. At that point we have established—CDC has established a network of laboratories. The Laboratory Response Network for bioterrorism, which is a public health—part of the public health infrastructure to move these specimens or strains related to these high threat agents such as Bacillus anthracis into a setting where further confirmatory testing can be done. And so if someone has a bacillus species in their clinical laboratory they need to contact their local and state public health authorities and work with them to get that isolate into the Laboratory Response Network for bioterrorism. These laboratories are all connected to CDC. They are using standard protocols and reagents that have been provided by CDC and other partners in bioterrorism, and they have the ability to confirm, in almost all instances, an identification of Bacillus anthracis.

Now when we don’t have culture, when we don’t have an isolate, there are some other tests. These tests are less available in clinical laboratories and actually in some of the Laboratory Response Network as well. They can be used to confirm cases, but they are generally less available and some of them you actually have to come into CDC laboratories to get those tests. That’s the PCR test for detection of Bacillus anthracis DNA; the immunohistochemistry test, which uses antibodies that allow us to visualize Bacillus anthracis; and then the serology test, which is a research test that currently is only available at CDC.

Dr. Baker (moderator):
What you described sounded to me like sort of a 3 level system. In local hospitals, in local communities, the capacity is there to basically identify the organism, and that would lead the clinician in to make a report to the health department. That’s kind of that first level—is that right?

Dr. Perkins:
Exactly. After the bacillus species in the setting of clinically suspicious illness.

Dr. Baker (moderator):
And that would trigger that case report that you talked about earlier?

Dr. Perkins:
It should trigger that case report and that’s exactly what happened in the Florida situation.

Dr. Baker (moderator):
And the second level is more the Lab Network, that’s the more definitive identification. The third level are those very specialized tests that you mentioned at the end.

Dr. Perkins:
Yes.

Dr. Baker (moderator):
So it’s sort of a 3-tiered system.

Dr. Perkins:
That’s exactly right.

Dr. Baker (moderator):
Let’s go on to some other issues here. The question has come in regarding anthrax vaccine, whether or not it is available, whether or not it is the thing that should be done here in this setting. Could one of you help us with the issue of anthrax vaccine?

Dr. Stephens:
Sure. We both may want to comment. There is an anthrax vaccine; it was developed through the efforts of the Centers for Disease Control some years ago in prevention of disease when workers exposed to wool and goat hair became ill with wool sorter’s disease in the ‘50s and ‘60s when inhalational anthrax was a problem. The vaccine is currently not recommended except for those individuals who work with Bacillus anthracis. And, Brad, you may want to comment on that issue.

Dr. Perkins:
Yeah, the people that have generally been vaccinated with the anthrax vaccine in this country are those people that have an occupational risk for exposure. At this time, the vaccine is only used in those individuals as well as the military population, although we are actively vigilant for situations where it may be beneficial to use the vaccine in the civilian population.

Dr. Baker (moderator):
So basically what you are saying is, the general population does not need to even think about anthrax vaccine. That is not an issue. It is really related to those individuals that have a very clear risk of anthrax as a result of doing certain occupational things like the wool sorters and the things that you mentioned before.

Dr. Perkins:
Exactly.

Dr. Baker (moderator):
Now there are other people out there that in their work are concerned about being exposed to anthrax—for example, first responders, healthcare providers and those kinds of individuals, who, again, across the country, would have a very low likelihood of being in contact with anthrax. But again, people are starting to wonder, “Is this something I need to be thinking about in my occupation?” Obviously, not the traditional things that you talked about. Are we developing guidelines that go beyond those traditional occupations to think about other groups?

Dr. Perkins:
Well, the Advisory Committee for Immunization Practices, which is CDC’s recommendation for use of licensed vaccines, entertained this issue in quite a substantive way over the last couple of years. There was a statement made by that committee that suggests that there is no current need for any pre-exposure vaccination of specific populations in the United States. Populations that were considered included emergency first responders, law enforcement officials, persons that would receive suspicious packages in the laboratory. At that time there was a firm recommendation from the committee that there was no need for pre-exposure vaccination because there was no ability at that point to calculate risk versus benefit of that protection. Over the last month we are seeing the occurrence of cases and the occurrence of risk and I think that based on that change of risk that we are going to have to re-evaluate the need for vaccination in selected populations.

Dr. Baker (moderator):
So we are rethinking that question in light of recent events basically?

Dr. Perkins:
We are. We are.

Dr. Baker (moderator):
A different question on nasal swabs. We’ve heard about nasal swabs. You did a lot of nasal swabs in Florida, and that is happening now in various places around the country. Maybe, David, you can help us with this. What can you say about when it is indicated and what do nasal swabs really mean? What is the significance of that?

Dr. Stephens:
Nasal swabs, as Brad has indicated, were used and are being used in settings of epidemiological investigations regarding these anthrax outbreaks. However, they shouldn’t be used in an individual situation for making decisions. And I think that Brad would agree with that. The key element is that they serve a purpose in epidemiological investigation studies, but not for the individual decision-making regarding prophylaxis or treatment.

Dr. Baker (moderator):
Would you say it is fair to say that a nasal—a positive nasal swab is really more a measure of exposure? It means that person has been around the bacillus but it doesn’t have direct clinical implications in terms of triggering, say, drug use. Is that a correct statement?

Dr. Perkins:
That is exactly correct. Again, the decisions about antibiotic prophylaxis are driven by the epidemiologic investigation, and the nasal swabs, the environmental sampling, and the potential serology done are all adjuncts to the epidemiologic investigation, trying to draw circles around populations that are at risk. Those tests—none of those tests should be used to make individual decisions about this patient or this individual should be treated and this one should not.

Dr. Baker (moderator):
Let’s turn a little bit to sort of the early part of the action. You talked about this a little bit in your description of Florida. That’s this issue of a suspicious letter or a package. Many people now want to know what they should do. How does one identify a suspicious package? What are we now learning about how to handle these letters or packages from the ongoing investigations?

Dr. Perkins:
We are learning some interesting things. We are learning some things about human nature. We have literally—in the context of the multiple investigations that CDC is currently involved with—we literally interviewed hundreds of people that have been involved in handling or exposure to either confirmed or suspected envelopes or packages containing Bacillus anthracis. There are a couple of things that have emerged from that experience. First of all, when someone opens or finds a suspicious envelope or package that contains powder, we would strongly recommend that they do not carry the letter around an office environment, for example, and show it to people. We are finding that that’s quite a frequent response to finding something unusual or something that people don’t understand.

Secondly, we are finding that people often, when they get a powder or a substance and they don’t know what it is, they will do two things: they will try to smell it to determine what it is or they will try to look at it very closely. Both of those things are extremely dangerous practices if the material actually contains Bacillus anthracis spores.

Lastly, some recommendations have suggested that if a suspicious envelope or package is identified, that a plastic bag or a container should be identified and that the suspicious letter, or envelope, or package should be put inside that container. As we start to understand more about these exposures I would suggest that’s probably not what we want people to do. I think the most prudent advice at this point is that if something suspicious is received, that it is carefully laid down on the nearest flat surface, that it is left there, that the person and anybody else in that room leave the room and call 911 for assistance.

Dr. Baker (moderator):
Any further thoughts on that, David?

Dr. Stephens:
I certainly think that suspicion for anthrax and notifying your state health department and following the instructions that Brad just gave you is sound advice.

Dr. Baker (moderator):
Great. I want to thank both of you for being with us today and also for all that you are doing on this extraordinary situation here at CDC. Thank you for being with us today.

Drs. Perkins and Stephens:
Thank you.

Dr. Baker (moderator):
That brings our program really to a close. I want to say that at the completion of this broadcast, this program will be available online at the Web site address that is on your screen: www2.cdc.gov/phtn. For further information on the Health Alert Network that was mentioned before, there is a different Web address, and that’s on your screen as well. We also plan to rebroadcast this program on Monday, October 22, from 5:00 until 6:30 p.m. Eastern Daylight Time. At that point, please check satellite coordinates; they will be different from those today. Additionally, you may obtain a VHS tape of this program free of charge from the Public Health Foundation by calling 1-877-252-1200 between 9:00 and 5:00 Eastern Standard Time. International callers should call 301-645-7773. Thank you very much for joining us and we also want to again express our appreciation to our three experts for providing us with this exceptionally informative program. Thanks very much to Secretary Thompson and particularly thanks to our partners at the American Medical Association and the American Hospital Association. Thank you very much for being with us today.

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