Home

A message about anthrax from the Canadian Medical Association to physicians

Latest update: October 26, 2001

In the aftermath of the terrorists attacks of September 11 in the United Stated there has been an increasing number of reports of suspected exposure to anthrax and several cases of confirmed exposure in the US as a result of non-natural transmission. New cases of anthrax are continuing to be discovered in the US; however, at this time no confirmed cases or exposures are known to have occurred in Canada. Internationally recognized public health agencies are involved in assessing the situations in the United States.

In light of the context in which these cases have occurred, and the now accepted fact that the cause of the cases was non-natural transmission, the Canadian Medical Association is providing the following information to assist physicians in dealing with inquiries from patients. Because anthrax is a very rare disease in North America the public knows little about the disease.

Facts for patients about anthrax

  • Anthrax is an acute bacterial infection most commonly found in hoofed animals outside of North America but can also infect humans.
  • In humans, anthrax can infect the lungs (inhalation), skin (cutaneous), or the intestines (intestinal). Symptoms will often be seen within the first 7 days of being exposed.
  • The most severe of these three, inhalation (lung) anthrax starts out with flu-like symptoms but progresses to acute respiratory distress and shock over 3 to 5 days. Inhalation (lung) anthrax is very rare.
  • Skin or cutaneous anthrax appears as a red boil-like lesion that enlarges, forms an ulcer and blackens in the middle (the eschar). As with inhalation anthrax the skin form is not spread from person to person by casual contact. It can only be transmitted by direct contact with the drainage from an open sore.
  • In persons exposed to anthrax, infection can be prevented with antibiotic treatment. Early treatment is important.
  • Direct person-to-person spread of anthrax is not known to occur. Therefore, there is no need to treat contacts of persons ill with anthrax.

Information for physicians

The most important thing physicians can do is to become familiar with the signs and symptoms of anthrax and be vigilant in reporting possible cases to your local public health unit immediately.

Inhalation anthrax starts out with flu-like symptoms but progresses to acute respiratory distress with x-ray evidence of mediastinal widening and shock over 3 to 5 days. Canadian and American public health agencies are alerting health care providers to look for unusual cases of respiratory disease.

Patients may inquire whether there are any preventive measures they should be taking. Based on what we know right now, there is no need for people to take any extraordinary actions or steps. They should not go to a doctor or hospital unless they are sick. They should not buy and horde medicines or antibiotics. They should not buy gas masks. If anyone has been exposed, antibiotics are the appropriate preventive treatment. Experts do not recommend widespread use of antibiotics in the absence of suspected exposure because of the public health concerns of promoting antibiotic resistance, as well as concerns about individual risks of side effects in the probable absence of a mitigating therapeutic benefit.

There is a vaccine to protect against anthrax. It has been used for many years for individuals who likely have occupational exposure to anthrax, such as veterinarians. The full protective effect is present after a 6-dose course is completed over an 18-month period, and annual boosters are then needed to maintain immunity. Anthrax vaccine is not licensed for use in Canada and therefore is not widely available.

Gas masks that are available to the public are unlikely to be useful in providing protection. The quality of masks varies greatly, and masks need to be specifically fitted by a trained person. Filters need to be changed periodically. Further, to protect against an exposure the mask must be in place and operational at the time of exposure.

This information has been developed with reference to the following Web sources, where information about anthrax is available.