October 27, 2001

	Persons involved in an anthrax threat involving a letter or package with "powder" should report the incident immediately to the local law enforcement agency (911) for a threat assessment. The WA State Public Health Laboratory will only accept environmental samples for anthrax testing when law enforcement authorities, in consultation with Public Health, determine that a credible threat is present.
	Prophylactic antibiotics should be limited to persons with 1) potential aerosol exposure to a credible threat (as determined by law enforcement authorities in consultation with Public Health) and when no substance is available for testing, or 2) a confirmed anthrax exposure. Clinicians evaluating patients who may have been exposed to anthrax should have the patient report the incident immediately to local law enforcement (see above). If the clinician is concerned that a high-risk exposure (defined below) has occurred, please contact Public Health at 206-296-4774 (24 hours). Please consult with Public Health before starting anthrax post-exposure prophylaxis whenever possible.
	Detailed guidelines for handling suspicious packages, letters and substances can be found in the CDC Health Alert at: www.bt.cdc.gov/DocumentsApp/Anthrax/ 10122001Handle/10122001Handle.asp.

Assessment of individual risk of exposure:

	Factors that need to be assessed to define the nature of a possible exposure to anthrax include:
	1.	The credibility of the threat (as determined by law enforcement and/or Public Health);
	2.	Whether a potential human exposure occurred; and
	3.	The specific circumstances of the exposure (e.g. risk of inhalational or cutaneous anthrax)
	Clinicians should take a thorough history from patients with illness compatible with anthrax including occupation, travel in the past 60 days, and circumstances of any exposure to suspicious substances.
	Situations with higher credibility for the presence of anthrax: a distinct threatening message is sent with the powder or substance, or a suspicious letter or package is involved (see the CDC Health Alert for details).
	Situations with lower credibility for the presence of anthrax: powder is found without a note or is present in an expected mail envelope or package that is easy to trace to the sender.

Route of potential exposure - based on information available as of 10-25-01:

Inhalational anthrax generally requires exposure to fine powder (1-5 microns in size) necessary to get into the alveoli. It is technically difficult to disperse anthrax into particles this size. Re-aerosolization of particles deposited on clothing and other surfaces is thought to pose minimal to no risk. In the current anthrax attack on the Washington, DC area, the risk for aerosol exposure among persons exposed to anthrax powder in envelopes appears to be high. The risk of aerosol exposure would be expected to vary according to the specific characteristics of the anthrax preparation involved and the circumstances of exposure.

Inhalational anthrax would clearly be of concern with evidence of exposure to an aerosol of anthrax-contaminated powder. Examples include a fine powder contaminating the eyes, nose and throat; a credible threat or incident involving potential aerosolization based on information regarding the circumstances of exposure, a warning that an air handling system is contaminated or a warning that a biological agent was released in a public space.

Cutaneous anthrax is the most likely form of anthrax that could be caused by anthrax-contaminated letters and packages that did not have an obvious aerosolizing device. Given the characteristic clinical presentation and excellent prognosis if recognized early and treated, potential cutaneous exposures that do not pose a risk for aerosol exposure can be managed by observation for the development of a suggestive skin lesion and prompt treatment as clinically needed.