Anthrax Outbreak - Canada Quarantined 134 Premises in 2006

An anthrax outbreak that began in early July has claimed 637 animals and caused 134 premises to be quarantined in Saskatchewan, Canada, as of Aug. 10, according to the Canadian Food Inspection Agency (CFIA). The outbreak is the largest on record to ever hit Saskatchewan. In Manitoba, Canada, CFIA officials confirmed anthrax cases on 18 premises, with 126 dead animals reported.

According to CFIA veterinarians, more than 250,000 animals have been privately vaccinated and 18,000 vaccinated by the Canadian government. Animals infected by the outbreak include cattle, horses, bison, sheep, and goats.

The bacteria, Bacillus anthracis, causes anthrax. The bacteria are found in two stages — the vegetative state and the spore state. The vegetative state is the growing, reproducing form of the bacteria found in infected animals and people. The vegetative form is the state that causes the disease, anthrax. If untreated the disease in animals is generally fatal. Anthrax organisms in animals or their secretions may be destroyed by pasteurization or ordinary disinfectants. However, if the animal carcass is opened and the organisms are exposed to air, they will form spores. Anthrax spores are highly resistant to heat, cold, chemical disinfectants and drying. The anthrax spore may live indefinitely in the soil of a contaminated pasture or yard.

Cattle and sheep are very susceptible to anthrax. Horses, swine, deer, and humans are less susceptible than cattle or sheep. Dogs, cats, and birds have been infected experimentally, but are less likely to become infected through exposure.

Infection in cattle, sheep, or horses usually is the result of grazing on infected pastures. The organisms usually enter through the mouth, and less often via nose or skin injury. Following ingestion or inhalation, the organisms spread rapidly throughout the entire body. Dead animals that are opened and not burned or buried provide an ideal source of the organism. It is imperative that diseased carcasses be cremated (burned to ashes) or buried deep and covered with quick lime before back filling with soil.

Anthrax spores may also spread by flooding pastures with contaminated water or dumping infected carcasses in streams or ponds. Flooding often contaminates Low lying ground or marshy areas, and resultant stagnant water holes may serve as a source of infection. Hay that is infested with spores may account for outbreaks of acute anthrax during the winter months. However, anthrax is predominantly a warm weather disease. Anthrax spores are known to survive in the soil 35-100 years or longer.

Anthrax may also be spread through wounds caused by blood sucking insects, dehorning, or castration. Humans may become infected by handling contaminated hides or wool, or by examining infected carcasses.

The symptoms associated with anthrax will depend on the species involved and the route of infection. When the anthrax organism enters the animal's body by mouth or nostrils, the symptoms occur soon after infection (acute form) followed rapidly by death. When infection takes place through the skin because of injury or insect bites, it appears localized at the site of injury in the initial stage. The affected area is initially hot and swollen, and becomes cold and insensitive. Later, the infection can become generalized. Anthrax usually is a fatal disease with no symptoms observed. Upon or near death, blood oozes from the body openings. This blood is heavily laden with anthrax organisms. There is a marked bloating and rapid decomposition of the carcass.

If the infection is less acute, there may be a sudden staggering, difficult breathing, trembling, collapse, and death. In horses, colic may be observed. Edema and swelling may be seen over the body, particularly at the brisket or chest. Illness is observed for one or two days, but it may last five days. Symptoms are preceded by fever, with a period of excitement in which the animal may charge anyone nearby. This excitable stage is followed by depression in cattle or sheep.

Sometimes in swine, the anthrax organism localizes itself in the throat area. The tongue, throat, and neck are extremely swollen and a frothy blood-tinged discharge comes from the mouth. Though this is the typical form of anthrax observed in swine, it may also occur in cattle and sheep. Not all cases of "sudden death" are anthrax, but if anthrax is suspected, confirmatory laboratory examination is needed. If anthrax is suspected, do not have your vet perform a necropsy. Using aseptic technique, have a veterinarian collect a jugular sample of venous blood and send or deliver it to the diagnostic laboratory in a sealed, sturdy, leak proof, iced container, with an accompanying history identifying it as an anthrax suspect.

Producers should take every precaution to avoid skin contact with the potentially contaminated carcass and soil. Protective, impermeable clothing and equipment such as rubber gloves, rubber or leather apron, and rubber boots with no perforations should be used. No skin, especially that which is compromised with wounds or scratches should be exposed. Disposable personal protective equipment is preferable, but if not available, decontamination can be achieved by washing any exposed equipment in hot water and detergent. Disposable personal protective equipment should be burned and buried with the carcass.

Your state animal health agency (Pennsylvania Department of Agriculture) can provide helpful advise on disposal of carcasses. Proper carcass disposal is important to prevent surface soil contamination. Vaccines are available to protect animals in endemic areas when outbreaks occur.

Always keep in mind that anthrax can cause serious disease in humans as well as animals. Three syndromes are recognized in man. The skin infection form is usually seen in people who work with animal carcasses, wool, hides or fur. The infections are seen as large, local abscesses often on the hand or finger. These skin infections can spread to the blood stream and cause serious illness or death. Inhaling the bacteria causes the pulmonary form. Most lung infections result in rapid death. The intestinal form results from eating the bacteria and is seen as violent intestinal pain with vomiting and bloody stools. A high mortality rate is seen with the intestinal form of anthrax. For this reason, great care should be taken to protect anyone handling the carcass or live animals suspected to have anthrax. Meat obtained from animals dying of unknown causes, or suspected of having anthrax or another infectious disease, should not be consumed.

In summary, anthrax is caused by bacteria that can exist in two forms. The vegetative form causes disease in both animals and man but is rapidly killed in unopened carcasses. The spore form lives in the soil for years. When the spores surface, they revert to the vegetative form and cause further disease when eaten by animals. Suspected cases of anthrax should be reported to your veterinarian first and then to state animal health agencies. Animal health officials are available 24 hours a day to assist your veterinarian in managing an outbreak and minimizing losses. Use caution when handling dead animals suspected to have anthrax. Suspicious cases should be reported to PDA at 717-772-2852 from 8AM to 4PM, and after normal working hours at 717-772-2852.