Anthrax is a zoonosis - a disease that is caught from animals. The name comes from the Greek word for coal, which refers to the black colour of the skin lesion. Skin infections account for most forms of the disease.
Anthrax occurs worldwide, but it is rare in animals and humans in Canada. People who work with animals and animal hides (mostly imported) are at some risk, especially in those parts of the world where anthrax is more common.
Information for Health Professionals
Anthrax is an acute infectious disease caused by a bacterium called Bacillus anthracis. The bacteria form spores than can stay viable in the soil for perhaps hundreds of years. The bacterium may infect humans and animals. In humans, anthrax can cause infection in three body systems:
Anthrax infection in humans is rare in Canada. The latest BC case was seen in 2001. More recently, two people were infected in 2006 in Saskatchewan during an outbreak among animals (mainly cattle). All these people developed skin infections and recovered. Human cases of digestive and lung anthrax have never been reported in Canada.
Skin infections account for 95% of all anthrax infections reported worldwide. Disease usually occurs 1 to 7 days after contact with an infected animal or animal product. A small bump appears on the skin which turns into an open wound with a black centre.
In a digestive infection, symptoms may include fever, loss of appetite, vomiting, and diarrhea.
Lung infections are the most serious type of infection. Symptoms include fever and sore throat followed by difficulty breathing.
Anthrax does not spread from person-to-person. It can spread in one of these ways:
- From infected animals or animal products.
- Humans can become infected with skin anthrax by handling products such as animal hides from infected animals.
- Digestive infections occur by eating undercooked meat from infected animals.
- Lung anthrax has been reported in factories where people breathe in spores from contaminated animal skins or wool.
Anthrax is most common in herbivores such as cattle, sheep, goats, and horses. These animals, when grazing, ingest anthrax spores that live in the soil and have recently been brought to the surface due to warm temperatures and/or heavy rainfall. Animals may also become infected by eating anthrax-contaminated feed. Anthrax outbreaks in animals occur worldwide.
In Canada, outbreaks have been reported in cattle in the western prairie provinces and in the free-ranging bison of the Northwest Territories.
Anthrax was deliberately prepared in a concentrated powder form and spread through the postal system in the United States in 2001 causing 22 cases of anthrax infection of the lungs and skin. To date, anthrax has not been used as a weapon in Canada.
Diagnosis of anthrax can be done in a number of ways, including:
- microscopic analysis of specimens
- culturing of specimens
- PCR testing
- ELISA testing of antibodies (Heymann 2008)
Anthrax infections can be treated with antibiotics. Consult your doctor immediately if you suspect you have been infected with anthrax.
The risk of anthrax infection in the general Canadian population is low. Laboratory workers, individuals who work with raw animal materials and military personnel can be vaccinated against anthrax to decrease their risk of infection. Farm animals at risk of anthrax should also be vaccinated against anthrax.
Anthrax is not common among animals in BC so there is little risk of anthrax if you work with animals in BC. Anthrax may be suspected in an animal that has died suddenly and has bloody discharge from the nose, mouth or rectum. If you suspect an animal has died from anthrax, contact your veterinarian immediately. Do not touch or move the carcass. The blood from an animal that dies from anthrax may expose other animals to the disease. Your veterinarian will advise you on the safest way to dispose of the animal.
A vaccine to protect animals against anthrax is available.
Animal hides pose a low risk of skin anthrax, and a very low risk of lung anthrax. Imported animal hides pose a higher risk than hides from North America. People working with animal hides (e.g. making drums) should only use hides that have been legally imported and processed to reduce the chance of anthrax transmission. If you develop skin lesions or fever within 7 days of handling an animal hide, seek medical care immediately.