Anthrax is a disease caused by the bacterium Bacillus anthracis. It is very rare in Ontario. The bacteria live naturally in soil and mostly affect farm animals like cows, sheep and pigs. People can sometimes contract anthrax when bacteria enter through cuts or abrasions in the skin after contact with an infected animal or contaminated animal products.
Anthrax has been used in the past as a bioterrorism weapon.
No case of anthrax related to bioterrorism has occurred in Canada.
There are four types of anthrax infection:
- Skin (cutaneous) anthrax infection is the most common and most easily treated. It occurs when anthrax bacteria come into contact with open skin.
- Lung (inhalational) anthrax infection occurs when anthrax bacteria are breathed in. Inhalational anthrax infection is the most lethal form of the disease.
- Digestive (gastrointestinal) anthrax infection is rare but occurs when anthrax bacteria are ingested by eating contaminated food.
- Injection anthrax infection is often associated with intravenous injection drug use, specifically heroin. This type of infection has never been reported in Canada.
How Anthrax Spreads
People can get anthrax if they have an open wound or sore and they:
- Touch an infected animal.
- Handle infected animal products, especially hides or skins.
- Touch soil that is contaminated. Articles and soil contaminated with anthrax bacteria may remain infective for years.
People can also get anthrax by:
- Eating raw or undercooked meat from infected animals.
- Breathing in anthrax bacteria (mostly affects people in high- risk jobs, such as those working with animal skins).
- Injection drug use.
Although there is no person -to- person transmission, there could be a possibility of exposure to a common source.
Symptoms & Illness
Symptoms of anthrax can appear anywhere from 1 to 7 days after exposure, but in some cases may take up to 60 days to develop. The symptoms of anthrax depend on the type of the infection:
- Skin (cutaneous) anthrax: Often starts with itching where the bacteria entered the body. A small blister can then form and later turn into a painless black sore, with swelling around it. Some people may also feel sick, with symptoms like fever, tiredness, or headache. If the sore is on the face or neck, the swelling can become serious and may be hard to breathe. Without treatment, the infection can spread inside the body and cause a serious, life‑threatening illness.
- Lung (inhalation) anthrax: This is the most serious and dangerous form of the disease. It usually starts with flu‑like symptoms such as fever, feeling unwell, a mild cough, shortness of breath, nausea, or vomiting. These symptoms can quickly worsen, leading to severe breathing problems and shock, which can be fatal without treatment.
- Digestive (gastrointestinal) anthrax: May start with sores in the mouth or throat, as well as sudden stomach‑related symptoms such as nausea, vomiting, stomach swelling and pain, and fever. In severe cases, there may be bleeding in the digestive system and serious infection in the abdomen.
- Injection anthrax: Has never been reported in Canada but has been reported elsewhere in patients with a history of heroin use. Most people develop a serious infection in one specific area of the body, with noticeable swelling of the skin and soft tissue. Fever is often mild or may not occur, and the pain is usually less severe than with other serious skin infections. Not all cases have localized injection- related sores; some people show signs of a more general illness affecting the whole body.
Any form of anthrax can spread through the blood or lymph system and cause serious illness throughout the body. In some cases, the infection can reach the brain and cause anthrax meningitis (swelling around the brain and spinal cord), even in people who do not have obvious symptoms elsewhere. Anthrax meningitis is severe and is fatal in most cases.
How to Handle a Potential Exposure
If you suspect that you or anyone has been exposed to anthrax or has received a suspicious package, immediately dial 9-1-1 (emergency services). Emergency services personnel will assess the situation and advise you on what to do next. Additional precautions you can take to protect yourself:
- Do not shake or empty the contents of a suspicious package.
- If a package is opened with powder or powder spills, do not try to clean up the powder. Carefully cover the spilled contents with anything (e.g., clothing, paper, trash can, etc.) and leave the immediate area. Close the door or section off the area to prevent others from entering.
- Wash your hands and other exposed areas with soap and water. Do not use bleach or other disinfectants on your skin as it may cause skin damage.
- If powder may have spilled on your clothing, remove contaminated clothing as soon as possible and place in a sealed bag. The clothing bag should be given to emergency responders for proper handling.
- Take a shower with soap and water as soon as possible.
- List all people who were in the room or area when suspected exposure occurred.
- Keep the list as it may be requested by local public health authorities for follow- up investigation and advice.
Seeking Medical Care and When to Isolate
If you think you have been exposed to anthrax or develop symptoms of anthrax, call 9‑1‑1. Persons who may have been exposed to anthrax are not contagious, so quarantine is not appropriate.
Diagnosis & Treatment
Anthrax infection is diagnosed with laboratory tests which could include a blood test or testing other bodily fluids. A health care provider diagnoses anthrax by considering a person’s symptoms, their possible exposures, and the results of laboratory tests.
Anthrax may be treated with antibiotics. Treatment should start as soon as possible. Care should be guided by an infectious disease specialist.
Post- Exposure Prophylaxis
Antibiotics are used when someone may have been exposed to anthrax, even if they do not feel sick yet. Antibiotics should be started as soon as possible after exposure to help prevent illness. In situations with high- risk exposure, anthrax vaccine may be given along with antibiotics if available.
If you think you or someone else has been exposed to anthrax, or if you receive a suspicious package, call 9-1-1. Decisions about post exposure prophylaxis are made in consultation with public health and infectious disease experts.
Anthrax Vaccine
In Canada, the anthrax vaccine (BioThrax®) is approved by Health Canada for limited use and is available to people higher at risk, such a lab workers and those who work with animals.
Date modified: June 17, 2026
