Anthrax: What Every Clinician Should Know, Part 2
(November 1, 2001)
(View the webcast on the University of North Carolina School of Public Health site.)
What I’d like to do next is I’d like to go into some of the clinical signs and symptoms that have been associated with anthrax and if I could have the first slide.
The first slide highlights the fact that anthrax is an infectious disease, and it is caused by a gram-positive spore of bacteria, and it naturally occurs in farms and wild animals, but I think the key thing that we have to continue to emphasize over and over and that is there is no human-to-human transmission. It does not occur.
If I can have the next panel. The following clinical descriptions of anthrax are really based on experiences in adults, and I’m going to start out with the form that is the rarest and the one that we don’t really see that often and that is the gastrointestinal anthrax which is usually characterized by severe abdominal pain or distress, and a lot of times this may be followed by fever and signs of septicemia. Occasionally, because the toxin really impacts the various organs of the body and causes a bleeding disorder, these patients may manifest bloody vomiting or diarrhea. One other form that is very rare, but I think we have to pay some attention to, is the oropharyngeal involvement where you can have some lesions on the back of the tongue, and patients may complain of sore throats and dysphagia and note some fever and cervical lymphadenopathy. Usually this happens as a result of eating contaminated or poorly cooked meat that is infected with anthrax. The mortality rate is about anywhere from about 25-60%. Next slide.
Probably the most common form of anthrax in which we see in about 95% of the occurrences is the cutaneous form. Usually it starts out looking like just like a little insect bite on the skin, which later very rapidly develops as a papule, and it slowly develops little blister-like, vesicular-type lesions surrounding the sore and then progresses to a black necrotic center or ulcer in the center of this lesion. A lot of this…quite frequently, we see a lot of swelling and edema or redness that surrounds this eschar associated with this. Next slide.
This slide depicts how—if you look at picture here you see the vesicle starting on Day 2 noted and then eventually—it is such a classical presentation you really shouldn’t be able to miss this if you have had some experience with this and you see that very large, huge—it’s anywhere from 1 to 3 millimeters in diameter—this really very black, sort of necrotic ulcerative lesion formation. Next slide.
And then, as you can see, different forms can appear on different parts of the body, most commonly those exposed areas like your hands, forearms and hands, or the face where you are most likely to see it. Next slide.
How you make the diagnosis: a lot of times you can just culture those vesicular fluids or the exudates or you have to remind yourself this is highly contagious if you have the content of this fluid getting on the surface of your hands. So we really want to caution everybody to be wearing gloves. Blood cultures can be positive with gram-positive rods. You can do it by biopsy. There is a polymerase chain reaction test in a couple of hours that can give you the answer, and there are other mechanisms and other diagnostic tools that can be used to make a diagnosis in a very quick period of time. The mortality is only about 20% without any antibiotic treatment. If you give them antibiotics it’s less than a 1% mortality associated with this.
The next panel. The one that has got everybody’s attention and is a frightening thing, not only I think for the public, but also for commissions, because this is the one form of anthrax we cannot afford to miss. One of the unique things about this inhalational anthrax is that the incubation period is so short with the time from starting the symptoms to sometimes mortality and death can be on the average of 3 days. So you don’t have the luxury of time progressing over a period of time. What happens is it’s a brief program that sort of resembles a viral respiratory illness. But what you will have is that these spores are engulfed by microphages as they are transported to the bronchial lungs and to the also surrounding lymph nodes. It starts out insidiously, sort of a biphasic type of phase. They will complain of malaise, low-grade fever; a lot of times they will have a nonproductive cough and then they will feel better after a while. Then they go into that second phase, which is a really abrupt onset which may be associated with a significant amount of shortness of breath. Some of them may complain of substernum chest tightness or chest pain associated with this. Then maybe 50% of them can actually complain of acute abdominal pain or discomfort. Fifty percent also have meningitis that is associated with this which is a hemorrhagic meningitis which is usually fatal and they have a hematogenous spread as a result of this. So I want to just re-emphasize—it typically ranges (the symptoms) from 1-7 days with the average being 2-3 days. But there have been some cases because these spores can sometimes lie dormant inside the lungs and they can reactivate at a long period of time. That is why it is critical when we do prophylactic antibiotics that people have to take their entire 60 days if they have been exposed to a real case or highly suspicious case of anthrax. If I can get the next panel.
These patients will very rapidly go into respiratory failure and shock. So one of the things is, we try to look for some early signs because these symptoms can be very similar to other disorders such as influenza (or “the flu”). One of the key signs that sometimes can be noted very early is a widened mediastinum because of its involvement, as well as a pleural effusion, which in a lot of cases is very bloody. So that if you are doing an examination, you may hear these coarse crackles on examination of the lungs—be concerned that it may be a pleural effusion. Get a chest X-ray and a wide mediastinum and that’s key. These patients quite frequently do have positive blood cultures. Usually those gram-positive rods are identified within about 12 or 15 hours after taking the blood culture. So it is a rapid diagnosis and then you can get those gram-positive rods confirmed in the appropriate laboratories that have the expertise in order to do that. Polymerase chain reactions, diagnostic tools are available, as well as immunofluorescence and immunochemistry. Now the mortality rate is extremely high, even with possible supportive care and even with appropriate antibiotics. I have to re-emphasize, early diagnosis is the key in initiating antibiotics because this can go very, very rapidly. Next panel.
This highlights and just shows the widened mediastinum and also a little lymphadenopathy that is associated with this. Next slide.
I wanted to sort of give you a composite. These are all of the 8 patients that have been diagnosed with inhalational anthrax, and I want to just sort of highlight some real acute points when we look at all of their symptoms in totality. Note that out of the 8 patients, all of them did not have a fever. So don’t be caught up into the false security that I have to have a high fever in order for a patient to have inhalational anthrax. Two of our patients didn’t have that. Five out of 8 had sweats and chills. A lot of them had fatigue and malaise, and 5 out of 8 had nausea and vomiting and abdominal pain. So you might suspect it might be a gastroenteritis and viral gastroenteritis, which may sometimes lead you away from the respiratory infection. So I really, really have to emphasize that. Now where we see the difference from the flu, and a really key sign is that one, you have the absence of rhinitis and coryza, which we normally see with the flu, a lot of sneezing and coughing and runny nose. We have not seen that with the inhalational rhinitis. If you are concerned about bronchial pneumonia, that’s a bacterial etiology, we have not seen purulent sputum. So these coughs are usually dry associated with this. And diarrhea and pleuritic chest pain, a single case of sore throat, but be very concerned about a headache associated with this because I have to emphasize again we can have meningitis which is bloody, and you have to make that diagnosis very, very quickly.
- Page last updated November 20, 2002
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