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CDC Telebriefing Transcript
Drs. Feldman and Hayes Discuss Tularemia
March 7, 2002
CDC MODERATOR: Good morning. Well, I guess good afternoon, everyone.
Thank you for joining us on today's MMWR telebriefing. Today, we're going to
be focusing on the article, "Tularemia, United States, 1990 through 2000,"
and we have joining us Drs. Katherine Feldman and Dr. Ned Hayes, both who
are CDC's zoonotic disease experts.
I'd just like to take a moment to point out the other two articles that are
featured in this week's MMWR. They are the "Point of Purchase, Tobacco
Environment and Variation by Store Type, United States, 1999," and
"Variation in Homicide Risk During Infancy,, United States, 1989 to 1998."
If you have any questions on either of those two articles, you can call the
CDC press line at [404] 639-3286.
And now I'm going to turn it over to Dr. Feldman who's going to give a
couple brief remarks and then we will open it up to questions and answers of
which Dr. Feldman and Dr. Hayes will both be available.
Dr. Feldman.
DR. FELDMAN: Okay. Good morning.
Tularemia, often known as rabbit fever or deer fly fever, is a bacterial
zoonosis caused by Francisella tularensis. Following a dramatic decline in
the second half of the 20th Century, the incidence of Tularemia in the
United States remains low, with an average of 124 cases reported annually
during the period 1990 to 2000.
This indicates a low level of natural transmission, most often via tick
bites that occurred throughout the United States. Tularemia can be prevented
by using personal protective measures against tick bites by avoiding dead or
sick animals, and by wearing gloves when handling or dressing wild rabbits.
Understanding the epidemiology of tularemia enables clinicians and public
health practitioners to recognize unusual patterns of disease occurrence
that might signal an outbreak or a bioterrorism event. That's it.
CDC MODERATOR: We'll open it up for questions and answers now.
AT&T MODERATOR: Thank you, and, once again, ladies and gentlemen, if you do
have a question, please press the one at this time.
We do have a question from the line of Emma Hitz [ph] with Reuters Health.
Please go ahead.
MS. HITZ: Yes. Hi. I have two questions. Could you tell me what makes
Tularemia a suitable biological warfare agent, and also can you address why
you think Arkansas and Missouri contribute such a high number of cases to
this disease.
DR. FELDMAN: Okay; sure. I'll address the first question first. Francisella
tularensis is a category A agent and the reason for this is probably because
it's highly infectious. As few as 10 to 50 organisms, either inhaled, or
injected, can reliably cause disease. The disease that results can be a
severe disease and, in addition, it can be transmitted in various ways,
including through an aerosol exposure or through contamination of food and
water. Natural transmission also occurs via arthropod bites and direct
contact with infected animal tissues.
In a bioterrorism event, an aerosol release would probably have the greatest
adverse medical and public health consequences.
In response to your second question, why Arkansas and Missouri probably have
such a high number of cases, there's a lot that's still unknown about the
natural transmission of Tularemia, and we do know that the organism can
infect a vast array of mammals, birds, and ticks, and that most transmission
in the U.S., natural transmission, is through tick bites.
Both Arkansas and Missouri have prime habitat and conditions to favor tick
populations, including moist areas with thick underbrush.
In addition, in that area, there are at least two tick species that can
transmit the disease to humans, and once the disease is in ticks, it can
become endemic in the animal population.
MS. HITZ: Great; thanks a lot.
DR. FELDMAN: Sure thing.
AT&T MODERATOR: And we have a question from the line of Kim Dixon with
Bloomberg News. Please go ahead.
MS. DIXON: Hi; thanks. Two questions. The first is, Can you break it down in
the last decade. You said it's an average of 124 reported cases a year. Is
there a trend in one direction or the other, or is it more or less the same?
And, also, what's the fatality rate?
DR. FELDMAN: There was not a significant trend noted. In the text of the
article, you'll note that the disease is nationally notifiable. However,
there was a period in the middle of the decade from mid '91 until 1999,
where the disease was not nationally notifiable.
So there wasn't a noticeable trend throughout the decade and that can be
attributed to both the lapse in notifiable status and just also random
variation in natural transmission of Tularemia.
MS. DIXON: And the fatality rate? What percentage of people who get it--
DR. FELDMAN: Oh, right; right. Okay. So prior to the antibiotic era, the
untreated cases had an overall mortality rate of 5 to 15 percent, and that
is overall. Tularemia is an interesting disease in that it can result in
various clinical presentations, ranging from the most common form which is
the ulcer or glandular form, which is manifested by an ulcer and enlarged
lymph node, to the pneumonic form which is the most severe form.
So, again, overall, the case fatality rate in untreated patients is 5 to 15
percent. It can be as high as 60 percent in untreated patients with the
pneumonic form of the disease.
MS. DIXON: Is it similar to anthrax in that by the time the symptoms happen,
it's too late to treat? Or is it different in that way?
DR. FELDMAN: Absolutely not, and that's the next point I wanted to mention.
It is a treatable disease, it's a bacterial disease, it has a slower
progression than some of the other agents used in biological warfare such as
anthrax and plague. It has a slower progression, and this can lend itself to
maybe being more amenable to treatment early on, and once treated, survival
is quite high if it's treated promptly. Mortality is less than one percent.
MS. DIXON: Once treated; okay.
DR. FELDMAN: Once treated.
MS. DIXON: Thanks.
AT&T MODERATOR: And, again, ladies and gentlemen, if you do have a question,
please press the one at this time. And to the presenters on the call, no
further questions in queue.
CDC MODERATOR: Dr. Feldman, are there any points in your article that you
think are important for people to understand, or some things that you want
to highlight in this opportunity?
DR. FELDMAN: Well, I do just want to reinforce prevention measures against
Tularemia in natural occurrence, and that would be primarily because it's
most commonly transmitted through tick bites, by the use of personal
protective measures against tick bites. This would include avoiding
tick-infested habitats on the use of repellent, and frequent tick checks,
and wearing protective clothing against tick bites.
In addition, avoiding dead or sick animals, and wearing gloves when handling
or dressing wild rabbits can help prevent Tularemia.
CDC MODERATOR: Okay. Dr. Hayes, is there anything that you wanted to add?
DR. HAYES: I think Dr. Feldman's covered it very nicely. Thank you all very
much for your interest.
CDC MODERATOR: Okay. Thank you very much.
AT&T MODERATOR: And ladies and gentlemen, that does conclude your conference
for today. Thank you for your participation. You may now disconnect.
