Canadians are aware of and concerned about bioterrorism following recent reports of anthrax exposures, including one death in the US. No case of anthrax exposure has been reported in Canada since the terrorist attack of 11 September (as of 19 October 2001).

Recent developments will strengthen the capacity of Canada and British Columbia to effectively respond to biothreats. Public health and other emergency response personnel in British Columbia have developed a template for “Exposure to Biological Agents Response Plan” [1] to assist medical health officers and other regional officials in integrating bioterrorist response into existing local emergency response plans. The BC Centre for Disease Control (BCCDC) has an accredited biosafety level 3 laboratory, capable of testing hazardous biologic agents such as anthrax. And, the federal Minister of Health also recently announced a multimillion dollar plan to further enhance Canadian laboratory diagnostic capability, expand existing stockpiles of antibiotics such as ciprofloxacin and doxycycline to treat people exposed to biologic agents like anthrax, and provide emergency response training for front-line emergency responders.

Physicians play a critical role in surveillance of a possible bioterrorist event. Unusual illness patterns and diagnostic clues can signal such an event, and physicians should quickly report these concerns to their local public health unit. Any case of suspected or confirmed communicable disease that is not endemic to British Columbia (e.g., anthrax, plague, tularemia) or that occurs in a person without a travel history to an endemic area should be reported. A high index of suspicion is warranted since initial clinical presentation of many candidate bioterrorist agents is often a nonspecific, flu-like picture resembling other common community infectious diseases. Clues to a possible bioterrorist event that physicians may recognize and should report to public health include:

• Large numbers of ill persons with a similar clinical presentation 
• Clustering of a similar illness over time that could suggest a communicable disease outbreak or common-source exposure to an infectious agent 
• Higher morbidity or mortality associated with a common disease or failure of patients to respond to usual therapy

Physicians should familiarize themselves with the signs and symptoms of anthrax. The following information is intended to help physicians evaluate and counsel persons who may inquire regarding suspected anthrax exposure. Key epidemiologic aspects about anthrax are that the most probable route of exposure related to a bioterrorist event is through inhalation, and that anthrax is not transmitted person-to-person. Inhalation of an infectious dose of anthrax spores (lethal dose killing 50% of exposed humans is estimated at 2500 to 55,000 spores) requires a deep breath of a well dispersed, fine-particle aerosol containing sufficient concentration of B. anthracis.[2,3] These prerequisites of inhalation anthrax infection are not easily achievable. Letters or mailed packages or other deposits of unknown, non-dispersed powder pose an extremely low risk of inhalation exposure. Such environmental samples are not routinely tested, and persons should be instructed to throw the item away, clean up the powder, and wash their hands with soap and water. Nasal swabs, other testing, and antibiotic prophylaxis (e.g., ciprofloxacin or doxycycline) are not recommended for the above scenario.

If a letter or package states that there is anthrax in it or is associated with a credible threat, then this is a police matter and people should contact police through 911. If police and the local medical health officer determine there is a credible threat, then nasal swabbing would be appropriate. Swabs could be obtained using a regular bacteriology swab kit, collected from the anterior nose, and forwarded to the BCCDC with the usual lab requisition, marked as suspect bioterrorist event. A preliminary result will be reported back to the physician within 24 to 48 hours of receipt by BCCDC. In the event of a non-aerosolized exposure, the person could be instructed to package or otherwise isolate the suspect article if possible, and to wash their hands with soap and water. For an aerosol exposure, the individual should be instructed to disrobe and shower with soap and water, and to wash their clothes in the regular wash. Careful handling of contaminated clothes will minimize the already low risk of secondary fine-particle aerosol of any biomaterial on clothing. Grossly visible evidence of skin contact exposure can be disinfected by first washing with soap and water, then swabbing with a solution of dilute bleach (e.g., household 5% bleach, diluted 10 parts water to 1 part bleach) and finally rinsed with water to minimize skin irritation by the solution.[3] In consultation with the local medical health officer, antibiotics may be recommended in this situation.

No extraordinary preventive measures are currently recommended. People should not go to the hospital or doctor unless they are sick, nor should they seek to stock antibiotics at home or buy gas masks. Although there is a vaccine against anthrax, it is not licensed for use in Canada and is not readily available except for special indications, through Health Canada only.

Physicians should contact their local medical health officer if they have concerns or questions. There are also several informative Internet sites that could be consulted, many with links to related sites. These include BCCDC (www. bccdc.org [8]), Health Canada (www.hc-sc.gc.ca [9]), CMA (www.cma.ca [10]) and US CDC (www.cdc.gov [11]).

—British Columbia Centre for Disease Control, Divisions of Epidemiology and Laboratory Services

References

1.  Exposure to Biological Agents Response Plan (Municipal Emergency Plan–Template for Management) Bioterrorism Response Plan. September 2001. Internal document of City of Vancouver and Vancouver Richmond Health Board.

2.  Keim M, Kaufmann AF. Principles for emergency response to bioterrorism. Ann Emerg Med 1999;34:177-82. PubMed Abstract [12]

3.  Defense Intelligence Agency: Soviet Biological Warfare Threat (publication DST-1610F-057-86). Washington, DC: US Department of Defense, 1996.