Anthrax Q & A: Diagnosis
Anthrax is diagnosed by isolating B. anthracis from the blood, skin lesions, or respiratory secretions or by measuring specific antibodies in the blood of persons with suspected cases.
In patients with symptoms compatible with anthrax, providers should confirm the diagnosis by obtaining the appropriate laboratory specimens based on the clinical form of anthrax that is suspected (i.e., cutaneous, inhalation, or gastrointestinal).
- vesicular fluid and blood
Inhalation - blood, cerebrospinal fluid (if meningeal signs are present) or chest X-ray
Gastrointestinal - blood
are the standard diagnostic tests used by the laboratories?
Presumptive identification to identify to genus level (Bacillus family of organisms) requires Gram stain and colony identification.
Presumptive identification to identify to species level (B. anthracis) requires tests for motility, lysis by gamma phage, capsule production and visualization, hemolysis, wet mount and malachite green staining for spores.
Confirmatory identification of B. anthracis carried out by CDC may include phage lysis, capsular staining, and direct fluorescent antibody (DFA) testing on capsule antigen and cell wall polysaccharide.
is a nasal swab indicated?
Nasal swabs and screening may assist in epidemiologic investigations, but should not be relied upon as a guide for prophylaxis or treatment. Epidemiologic investigation in response to threats of exposure to B. anthracis may employ nasal swabs of potentially exposed persons as an adjunct to environmental sampling to determine the extent of exposure.
an X-ray for detecting anthrax?
A chest X-ray can be used to help diagnose inhalation anthrax in people who have symptoms. It is not useful as a test for determining anthrax exposure or for people with no symptoms.
get anthrax from contaminated mail, equipment or clothing?
In the mail handling processing sites, B. anthracis spores may be aerosolized during the operation and maintenance of high-speed, mail sorting machines potentially exposing workers. In addition, these spores could get into heating, ventilating, or air conditioning (HVAC) systems. CDC interim guidelines have been issued to advise workers on how best to protect themselves in the workplace.
- Page last updated December 2, 2002
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