Anthrax (Acute Bacterial disease)

Anthrax is an acute disease caused by infection with the spore-forming bacterium called Bacillus anthracis.

Disease Details

Introduction: Anthrax is also called as Woolsorters’ Disease and Splenic Fever. It is a serious bacterial, cutaneous, zoontic disease that affects the gastrointestinal and respiratory tracts of most mammals including humans, several species of birds, and herbivores. 

Cause: Bacillus anthracis. The bacteria may form spores that survive in the environment for more than 50 years.

Clinical Signs

• Sudden death (often within 2 or 3 hours of being apparently normal) is by far the most common sign;
• Very occasionally, some animals may show trembling, a high temperature, difficulty breathing, collapse and convulsions before death. This usually occurs over a period of 24 hours;
• After death blood may not clot, resulting in a small amount of bloody discharge from the nose, mouth and other openings

Diagnosis

• From clinical signs
• Rod-shaped bacteria surrounded by a capsule are visible in blood smears
• Post-mortem examinations should not be undertaken on suspected anthrax cases
• If a carcass is opened accidentally, the spleen is usually swollen and there is bloodstained fluid in all body cavities.

Treatment: Due to the rapidity of the disease, treatment is seldom possible, although high doses of penicillin have been effective in the later stages of some outbreaks.

Prevention: Infection is usually acquired through the ingestion of contaminated soil, fodder or compound feed. Anthrax spores in the soil are very resistant and can cause disease when ingested even years after an outbreak. The spores are brought to the surface by wet weather, or by deep tilling, and when ingested or inhaled by ruminants the disease reappears.

Where an outbreak has occurred, carcasses must be disposed of properly, the carcass should not be open (exposure to oxygen will allow the bacteria to form spores) and premises should be quarantined until all susceptible animals are vaccinated. 

Vaccination in endemic areas is very important. Although vaccination will prevent outbreaks veterinary services sometimes fail to vaccinate when the disease has not appeared for several years. But because the spores survive for such lengthy periods, the risk is always present.

Anthrax is a disease listed in the World Organization for Animal Health (OIE) Terrestrial Animal Health Code, 2011, (Article 1.2.3) and must be reported to the OIE (Chapter 1.1.2 – Notification of Diseases and Epidemiological Information).