Signs and Symptoms

  • Inhalation Route: Chest Cold Symptoms, Fever, Non-Productive Cough, Shortness of Breath, Shock, Cyanosis, Death
  • Ingestion Route: Intense Stomach Pain, Bowel Obstruction, Diarrhea, Fever, Dehydration, Death
  • Skin Route: Sores or Blisters on Exposed Skin
Symptoms of anthrax depend upon the method of transmission.

(a) Cutaneous anthrax features a painless, necrotic ulcer with a black scab and local swelling. Untreated cutaneous anthrax has a case-fatality rate between 5 and 20 percent.

(b) Ingestion causes oropharyngeal and GI anthrax. Initial symptoms of oropharyngeal anthrax are fever, sore throat, and difficulty swallowing. Acute symptoms include ulcer or scab involving the hard palate or tonsils, swelling of neck tissues, and abnormal enlargement of the lymph nodes. Initial symptoms of GI anthrax include fever, loss of appetite, nausea, and vomiting. Abdominal pain, bloody vomiting, bloody diarrhea, and possibly massive abdominal swelling may follow. In both cases, septic shock and death may follow.

(c) Initial symptoms of inhalation anthrax are mild and nonspecific and may include fever, malaise, fatigue, and mild cough or chest discomfort; acute symptoms of respiratory distress, fever, and shock follow, with death occurring shortly thereafter.

Incubation period is generally 1-6 days, although longer periods have been noted. Fever, malaise, fatigue, dry cough, and mild chest discomfort progresses to severe respiratory distress with dyspnea, diaphoresis, stridor, cyanosis, and shock. Death typically occurs within 24-36 hr after onset of severe symptoms.

Signs and Symptoms of Cutaneous Anthraxa

—Initial lesion is small papule or vesicle, which may be pruritic.
—By second day, papule ulcerates with central necrosis and drying.
—Painless, localized, nonpitting edema surrounds ulcerated area.
—Fine vesicles may encircle ulcer; these enlarge over next 1-2 days and may discharge serosanguineous fluid.
—After 1-2 days, painless black eschar forms over ulcerated area.
—Eschar sloughs off after 12-14 days.
—Lesions resolve without complications or scarring in 80%-90% of patients.
—Extensive nonpitting edema, lymphangitis, and painful lymphadenopathy may occur.
—Malignant edema is rare complication and is characterized by severe edema, multiple bullae, and shock.b
—Fever and malaise are common.a
—Lesions tend to occur on exposed areas of body (eg, hands, arms, face, neck).
—One outbreak in Thailand demonstrated the following cutaneous findings for 13 patients with cutaneous anthraxc:
   ~Eschar (85%)
   ~Blister (92%)
   ~Ulcer (23%)
   ~Edema around lesion (77%)
   ~Lymphadenopathy (100%)

Abbreviation: WBC, white blood cell.

aSee References: Gold 1955.
bSee References: Amadi 1974.
cSee References: Kunanusont 1990.
dSee References: Smyth 1941.
eSee References: Bravata 2007.
fSee References: Dixon 1999.
gSee References: Doganay 2009.

Signs and Symptoms of Inhalational Anthrax

—Illness may be biphasic, with an initial prodrome (which includes symptoms such as fever, malaise, fatigue, anorexia) followed by sudden increase in fever, severe respiratory distress, diaphoresis, and shock, if left untreated.
—Symptoms for 10 patients with inhalational anthrax identified during the 2001 US outbreakb-c:
   ~Fever, chills (100%) (7 were febrile on initial presentation)
   ~Sweats, often drenching (70%)
   ~Fatigue, malaise, lethargy (100%)
   ~Cough (minimally or nonproductive) (90%)
   ~Nausea or vomiting (90%)
   ~Dyspnea (80%)
   ~Chest discomfort or pleuritic pain (70%)
   ~Myalgias (60%)
   ~Headache (50%)
   ~Confusion (40%)
   ~Abdominal pain (30%)
   ~Sore throat (20%)
   ~Rhinorrhea (10%)
—In the 2001 US outbreak, no evidence of a mild form of inhalational anthrax was detected through follow-up serologic testing of exposed persons.b
—A systematic review of 82 inhalational anthrax cases reported between 1900 and 2005 found that the most common symptoms or findings on admission included the followingd:
 ~Abnormal lung findings (80%)
 ~Fever or chills (67%)
 ~Tachycardia (66%)
 ~Fatigue or malaise (64%)
 ~Cough (62%)
 ~Dyspnea (52%)
 ~All 26 patients who had chest radiography had abnormal findings, including pleural effusion (69%) or widened mediastinum (54%).

Abbreviations: CFR, case-fatality rate; CT, computed tomography; SGOT, serum glutamic oxalacetic transaminase; SGPT, serum glutamic pyruvic transaminase; WBC, white blood cell.

aSee References: Meselson 1994.
bSee References: Baggett 2005.
cSee References: Jernigan 2001.
dSee References: Holty 2006 : Systematic review: a century of inhalational anthrax cases from 1900 to 2005.
eSee References: Bravata 2007.
fAlveolar-arterial oxygen gradient >30 Hg on room air; O2 saturation <94%.

Signs and Symptoms of Gastrointestinal Anthrax

—One outbreak of GI anthrax in Uganda demonstrated the following findings in 143 patientsa:
   ~Fever (may be low-grade) (70%)
   ~Abdominal tenderness (85%)
   ~Diarrhea (80%; bloody in only 5%)
   ~Vomiting (may be coffee-ground or blood-tinged) (90%)
   ~Headache (100%)
   ~Pharyngeal edema (10%)
—Ascites may develop 2-4 days after onset (fluid may be clear or purulent)b and in rare instances GI anthrax cases may present with progressive ascites without other classic symptoms. c
—Ulcerations can occur anywhere along the GI tract and may cause hemorrhage, obstruction, or perforation.d
—If the patient survives, symptoms last about 2 wk
—One outbreak of oropharyngeal anthrax in Thailand demonstrated the following findings for 24 patientse:
   ~Neck swelling (100%)
   ~Fever (96%)
   ~Sore throat, dysphagia (63%)
   ~Mouth or pharyngeal ulcerative or necrotic lesions (100%) (pseudomembranes also were noted in some patients)
   ~Respiratory distress (25%)
   ~Hoarseness (8%)
   ~Sensation of a "lump in throat" (8%)
   ~Diarrhea (4%)
   ~Bleeding from the mouth (4%)

Abbreviations: GI, gastrointestinal; WBC, white blood cell.

aSee References: Ndyabahinduka 1984.
bSee References: Dixon 1999.
cSee References: Hatami 2010.
dSee References: Sirisanthana 2002.
eSee References: Sirisanthana 1984.
fSee References: CDC 2001: Investigation of anthrax associated with intentional exposure and interim public health guidelines, October 2001.
gSee References: Beatty 2003.
hSee References: Bravata 2007.
iSee References: Doganay 1986.
jSee References: Doganay 2009.

Signs and Symptoms of Anthrax Meningitisa-d

—May occur as complication of cutaneous, inhalational, or gastrointestinal anthrax, and symptoms of primary site of infection usually will be present; however, meningitis may be the presenting illness.
—Characteristic features of bacterial meningitis usually present (eg, fever, nuchal rigidity, headache, change in mental status, seizures).
—Nausea and/or vomiting are common.
—Hemorrhagic meningoencephalitis is a characteristic presentation.

Abbreviations: CSF, cerebrospinal fluid; CT, computed tomography; MRI, magnetic resonance imaging; WBC, white blood cell.

aSee References: Dixon 1999.
bSee References: Rangel 1975.
cSee References: Meyer 2003.
dSee References: Sejvar 2005.
eSee References: Lanska 2002.
fSee References: Doganay 2009.
gSee References: Bravata 2007.

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