Anthrax (Bacillus anthracis)
2010 Case Definition

Clinical Description

Cutaneous Anthrax:

An acute illness, or post-mortem examination revealing a painless skin lesion developing over 2 to 6 days from a papular through a vesicular stage into a depressed black eschar with surrounding edema. Fever, malaise and lymphadenopathy may accompany the lesion.

Inhalation Anthrax:

An acute illness, or post-mortem examination revealing a prodrome resembling a viral respiratory illness, followed by hypoxia, dyspnea or acute respiratory distress with resulting cyanosis and shock. Radiological evidence of mediastinal widening or pleural effusion is common.

Gastrointestinal Anthrax:

An acute illness, or post-mortem examination revealing severe abdominal pain and tenderness, nausea, vomiting, hematemesis, bloody diarrhea, anorexia, fever, abdominal swelling and septicemia.

Oropharyngeal Anthrax:

An acute illness, or post-mortem examination revealing a painless mucosal lesion in the oral cavity or oropharynx, with cervical adenopathy, edema, pharyngitis, fever, and possibly septicemia.

Meningeal Anthrax:
An acute illness, or post-mortem examination revealing fever, convulsions, coma, or meningeal signs. Signs of another form will likely be evident as this syndrome is usually secondary to the above syndromes.

Suspected

An illness suggestive of one of the known anthrax clinical forms. No definitive, presumptive, or suggestive laboratory evidence of Bacillus anthracis, or epidemiologic evidence relating it to anthrax.

Probable

A clinically compatible illness that does not meet the confirmed case definition, but with one of the following:

• Epidemiological link to a documented anthrax environmental exposure;
• Evidence of B. anthracis DNA (for example, by Laboratory Response Network [LRN]-validated polymerase chain reaction) in clinical specimens collected from a normally sterile site (such as blood or cerebrospinal fluid [CSF]) or lesion of other affected tissue (skin, pulmonary, reticuloendothelial, or gastrointestinal);
• Positive result on testing of clinical serum specimens using the QuickELISA^TM (enzyme-linked immunosorbent assay) Anthrax-PA (protective antigen) kit;
• Detection of Lethal Factor (LF) in clinical serum specimens by LF mass spectrometry;
• Positive result on testing of culture from clinical specimens with the RedLine Alert test.

Confirmed

A clinically compatible illness with one of the following:

• Culture and identification of B. anthracis from clinical specimens by the LRN;
• Demonstration of B. anthracis antigens in tissues by immunohistochemical staining using both B. anthracis cell wall and capsule monoclonal antibodies;
• Evidence of a four-fold rise in antibodies to protective antigen between acute and convalescent sera or a fourfold change in antibodies to protective antigen in paired convalescent sera using Centers for Disease Control and Prevention (CDC) quantitative anti-PA immunoglobulin G (IgG) ELISA testing;
• Documented anthrax environmental exposure AND evidence of B. anthracis DNA (for example, by LRN-validated polymerase chain reaction) in clinical specimens collected from a normally sterile site (such as blood or CSF) or lesion of other affected tissue (skin, pulmonary, reticuloendothelial, or gastrointestinal).

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