DASG-PPM-NC 23 October 2001

INFORMATION PAPER

SUBJECT: Clinical Features of Anthrax Infection in Humans.

1\. Purpose. In light of the rapidly evolving outbreak of anthrax in the
United States, Army health care providers must be aware and remain
vigilant concerning the various clinical presentations of anthrax to
ensure early diagnosis and timely treatment. This information
supplements the guidance issued by The Surgeon General on 16 Oct 01 (ref
2.e.).

2\. References.

a\. US Army Medical Research Institute of Infectious Diseases. Medical
Management of Biological Casualties, 4th ed. 2001 Feb
(<http://www.usamriid.army.mil/education/bluebook.html>).

b\. FM 4-02.33. Control of Communicable Diseases Manual. 17^th^ Edition.
Feb 2000.

c\. CDC Health Advisory: How To Handle Anthrax And Other Biological
Agent Threats, Available at http://www.bt.cdc.gov.

d\. Inglesby TF, Henderson DA, Bartlett JG, et al. Anthrax as a
biological weapon: medical and public health management. JAMA
1999;281:1735-1745.

e\. Memorandum, MCHO-CL, 16 Oct 01, Subject: Management of Patients with
Potential Exposure to Anthrax Spores.

3\. Epidemiology. Anthrax is a disease caused by the spore-forming
bacterium *Bacillus anthracis*. Anthrax is a natural infection of
grazing mammals. Spores can persist in the environment for years. Spores
infect humans through breaks in the skin, through ingestion and through
inhalation into the lungs. The incubation period for anthrax is 1-6
days, although much longer incubation periods are thought to be
possible.

4\. Clinical Presentation. Anthrax is an illness with acute onset
characterized by several distinct clinical forms: inhalation, cutaneous,
intestinal, oropharyngeal, and meningeal. Each of these clinical forms
can progress to septicemia and multi-system infection in humans.

5\. Symptoms, signs, and other findings.

a\. Inhalational anthrax.

\(1\) Symptoms. Typically begins with a brief prodrome resembling a
viral respiratory illness (fever, malaise, fatigue, cough, and mild
chest discomfort) rapidly followed by development of severe respiratory
distress with dyspnea, diaphoresis, stridor, and cyanosis. Shock and
death occur within 24-36 hours after the onset of severe symptoms.

\(2\) Signs. During the prodrome, physical findings are typically
non-specific.

\(3\) Other findings. Progressive hypoxia can be demonstrated during the
phase of respiratory distress. A widened mediastinum is sometimes seen
on x-ray late in the course of illness, and correlates with a pathologic
finding of hemorrhagic mediastinitis, the "classic" presentation of
inhalational anthrax.

b\. Cutaneous anthrax.

\(1\) Symptoms. Patient presents complaining of a painless or perhaps
pruritic skin lesion, usually on the head, neck, forearm, or hand. Some
patients may have constitutional symptoms of systemic illness associated
with regional anatomic involvement. Late in the course, patient may
develop sepsis, leading to death in up to 20% of untreated individuals.

\(2\) Signs. Physical exam reveals a solitary skin lesion that begins as
a pruritic papule or macule and evolves into a round ulcer by the second
day. Subsequently, small (1 to 3 mm) vesicles can appear which may
produce a clear fluid. Within a few days, the lesion progresses to a
painless, depressed, black eschar that is often surrounded by edema. The
eschar will dry and fall often within 1 or 2 weeks. Regional symptoms
(lymphangitis, lymphadenopathy) are usually accompanied by systemic
symptoms.

\(3\) Other findings. Gram stain of fluid from vesicular lesions can
demonstrate characteristic organisms.

c\. Intestinal.

\(1\) Symptoms. Deposition of spores in the lower gastro-intestinal
tract can lead to nausea, vomiting, and malaise. This can rapidly
progress to bloody diarrhea, abdominal pain, or symptoms of sepsis. Some
individuals will develop a swollen abdomen.

\(2\) Signs. Physical exam may demonstrate an acute abdomen, the
presence of ascites, and the presence of blood in the stool. Advanced
disease may be characterized by signs of sepsis.

d\. Oropharyngeal.

\(1\) Symptoms. Patient will present complaining of a lesion in the
mouth or soreness in the throat (esophageal). This may be accompanied by
fever.

\(2\) Signs. Physical exam may identify an oral ulcer with associated
regional lymphadenopathy and edema. Alternatively, tenderness may be
localized to the throat (esophageal region).

\(3\) Endoscopy may demonstrate the presence of an esophageal ulcer.

e\. A meningeal form of the disease can present as acute onset of high
fever with meningismus, frequently with convulsions and loss of
consciousness. Alternatively, this form of the disease can follow after
onset of one of the other forms.

COL DeFraites/DSN 761-3146.

Approved by COL Thresher