There have been no cases of anthrax in Washington State. However, recent events emphasize the need for clinicians to maintain vigilance regarding any unusual disease clusters or manifestations that might represent an intentional outbreak, particularly among mail handlers at this time.

Inhalational anthrax usually presents as a brief prodrome resembling a viral respiratory illness followed by development of hypoxia and dyspnea, with radiographic evidence of mediastinal widening. Pleural effusions may be present, focal infiltrates are not typically seen but can occur. CT scans on some cases have shown mediastinal lymphadenopathy and pleural effusions. The incubation period of inhalational anthrax is reported to be typically between 1 and 7 days (range possibly up to 60 days). Initial symptoms include fever, dyspnea, cough, headache, muscle aches and malaise. Two recent cases also had GI symptoms including nausea, vomiting and diarrhea. These symptoms may progress to respiratory failure and shock. Meningitis frequently develops, and the spinal fluid may be hemorrhagic. Case-fatality rates are extremely high, even when appropriate antibiotics are administered. Early treatment in the prodromal stage is much more effective in preventing severe illness and death. Appropriate clinical specimens for diagnosing inhalational anthrax include blood, (Gram stain may be positive on unspun blood in advanced disease), pleural fluid, and if meningeal signs are present, CSF. See Tables for treatment and prophylaxis recommendations.

Avoid prescribing unnecessary antibiotics

Public Health recommends physicians NOT prescribe prophylactic antibiotics for the general public. There have been no cases of anthrax in our area. Prophylactic antibiotics should be limited to persons with a known exposure to anthrax or a credible threat as determined after a law enforcement investigation in consultation with Public Health. Clinicians seeing patients who report they may have been exposed to anthrax should see Risk assessment and response to possible anthrax exposures for clinicians.

Anthrax vaccines are not commercially available or recommended

There is currently no indication for the use of anthrax vaccine. At this time, anthrax vaccine is in limited supply and only available for military personnel at risk for potential exposure to anthrax in combat settings. Anthrax vaccine is not available to the general public or the medical community. Anthrax vaccination currently requires 6 shots over an 18-month period with periodic boosters.

There is NO role for nasal swab testing in clinical decision-making

There is no screening test available for the detection of anthrax infection in asymptomatic persons. Public Health discourages the use of nasal swabs for assessing patients concerned about exposure to anthrax.
A negative nasal swab result does not rule-out anthrax exposure. Decisions regarding administration of antibiotic prophylaxis for anthrax should be made based upon the risk of exposure, not the results of nasal swab testing.

Nasal swab testing for anthrax spores is used in epidemiologic investigations of persons with a known exposure to anthrax or to a credible threat as determined after a law enforcement investigation in consultation with Public Health. The results are used to guide further investigation and to determine the source and extent of exposure in a population, not to determine which individuals should be given preventive therapy. The sensitivity and specificity and clinical value of nasal swab testing are unknown.