Anthrax

Cause of Anthrax

Anthrax is a bacterial disease caused by Bacillus anthracis. When an animal dies of anthrax, spores can form by bacteria either being discharged from the animal or exposed to oxygen after opening the carcass. These spores are highly resistant and can survive in the soil through extremes in temperature and moisture. Anthrax is a zoonotic disease, which means it can be transmitted to humans. However, human infections are extremely rare.

Where Anthrax is Found

The spores survive in the soil for a long time and they are very buoyant. The spores may be brought to the surface of the soil when environmental conditions favour exposure of buried spores. Periods of flooding can move spores up to the soil surface and drying of wet areas will expose spores to grazing livestock. Disruption of the soil by excavation can also bring spores to the surface. When animals graze on soil where spores are present, they can ingest the bacteria directly from the soil or from plants. Cases of naturally-occurring anthrax are reported every year in Canada, particularly in locations where these particular climatic conditions are present.

Symptoms

Symptoms vary, and in most cases animals are found dead. Symptoms, when seen, include staggering, shortness of breath, trembling, collapse, a short period of convulsions and death. These symptoms are usually quite rapid. Also common are bloody discharges from body openings (e.g. the nose).

If anthrax is suspected, the carcass should not be moved or opened.

There is a large amount of bacteria contained in the carcass at the time of death and efforts should be made to prevent contamination of the environment with blood that can contain bacteria. The bacteria in the blood form spores when they come in contact with the air. Anthrax often reoccurs on the same pastures in subsequent years. Contact your local veterinarian immediately if anthrax is suspected. Anthrax is a reportable disease in Saskatchewan.

When to Alert the Vet

All confirmed cases must be reported within 24 hours to:

Ministry of Agriculture, Livestock Branch
Phone: 306-787-2150

It is also reportable to the Canadian Food Inspection Agency (CFIA).

Prevention and Treatment

Prevention is the best course of action and vaccination is the best method to protect against anthrax. The Sterne vaccine is the only licensed vaccine in Canada, and is only labelled for use in cattle, sheep, horses, goats and pigs. It may be used off-label for some species (e.g. bison) - consult your veterinarian for information on off label use. The vaccine will produce immunity, but requires seven to 10 days for immunity to develop. If anthrax is suspected, early diagnosis and treatment are important because of the rapid action of the disease. Anthrax can be treated with antibiotics that will kill the bacteria, but this does not offer long-term protection against infection. Antibiotics and the vaccine cannot be used at the same time because antibiotics will prevent the vaccine from working. If antibiotics are used, vaccination must be postponed until the effect of the antibiotic has worn off. Your local veterinarian is the best source of information on treatment and prevention methods for anthrax.

Risk to Other Animals

Although all mammals are susceptible to anthrax, it is primarily a disease of herbivores. Cattle, bison, sheep, goats and horses are highly susceptible. Omnivores, like pigs, and carnivores, such as dogs and cats, are less susceptible and can sometimes be exposed to the bacterium repeatedly before becoming infected. Birds and wildlife also appear to be at a lower risk for anthrax.

Saskatchewan Anthrax Response Plan

As of April 1, 2013, the CFIA stopped responding to cases of anthrax. The Saskatchewan Ministry of Agriculture has established a provincial anthrax response strategy to assist affected producers so that animal and public health are protected.

Anthrax remains a federally reportable disease; therefore, laboratories and veterinarians will continue to report all anthrax cases to the CFIA. In addition, laboratories and veterinarians must notify the office of the provincial Chief Veterinary Officer of anthrax cases within 24 hours.

The Ministry of Agriculture will pay for anthrax testing done at Prairie Diagnostic Services in Saskatoon. The ministry will provide carcass-side test kits to veterinary clinics serving high-risk areas of the province.

When anthrax has been confirmed on a farm, the Ministry of Agriculture will quarantine the affected pasture and exposed (or potentially exposed) animals to prevent the spread of anthrax through the movement of animals. This quarantine will begin on the day of the first anthrax death and will end seven days after the last anthrax death, as long as affected carcasses have been properly disposed of. This is necessary to protect animal and public health. An inspector, or designated representative, will visit the farm to determine the source of the anthrax and to trace animal movement on and off the farm in the last seven days. Information will be provided on how to dispose of the carcass and how to clean and disinfect contaminated areas. A follow-up visit will be arranged to confirm that carcass disposal, cleaning and disinfecting has been satisfactorily completed.

The above activities will be carried out by Ministry of Agriculture inspectors or their designated representatives. In many cases, veterinarians will be asked to act as designated representatives on behalf of the ministry to provide information on anthrax prevention and management, carcass disposal, cleaning and disinfecting directions, and confirmation that these activities have been completed. When private veterinarians are acting under the direction of the ministry for the purposes of anthrax response, the fees for their services will be paid by the ministry.

Costs related to carcass disposal, cleaning, disinfection and any other management procedure to control anthrax, such as vaccination or treatment, are the responsibility of the producer.

The following table is a list of anthrax outbreaks occurring in Saskatchewan, dating back to the introduction of the provincial Anthrax Response Program in 2014.