Anthrax Image from Centers for Disease Control and Prevention's Public Health Image Library
What is anthrax?
Anthrax is an acute disease caused by infection with the spore-forming bacterium called Bacillus anthracis. It can affect a wide variety of domestic and wild animals. The disease usually occurs very suddenly in cattle and sheep. Affected animals are found dead often with no previous signs of illness. Humans are also susceptible to anthrax, although in Australia human cases are very rare. In this country, the risk of human infection occurs when examining, skinning or cutting up an infected carcass.
What triggers an outbreak of anthrax?
Anthrax bacteria that have been long-buried in the soil may be exposed after heavy rainfall or earthmoving such as that undertaken in road or channel building. Outbreaks of anthrax are not unusual during the warmer months when the weather is dry and livestock forage deeper into the soil when eating grass.
What are the symptoms of an anthrax infection?
Just prior to death, animals may show signs of high fever. Livestock owners usually report unexplained, sudden deaths of livestock. Dark tarry discharges from the external orifices of dead animals may be observed.
What is the history of anthrax in Australia?
Anthrax outbreaks have been recorded in Australia for over 150 years. Most outbreaks occur within Gippsland and the ‘anthrax belt’ which extends from the northern area of Victoria, through to the central pastoral grazing areas of New South Wales. However, an outbreak in January 2008 in New South Wales occurred on properties outside the anthrax belt. The government subsequently found historical records that indicate that there had been cases of anthrax in the area in the early 1900s. Prevailing climatic conditions and soil disturbance may have allowed cattle to be exposed to anthrax spores previously buried in the soil.
How does anthrax travel?
Anthrax does not spread from live animals to other animals but it can spread from the carcass of an animal killed by anthrax to other animals in contact with the carcass. The anthrax spores may lie dormant in soil for many years and infect animals that graze contaminated areas.
Anthrax skin lesion
What measures are in place to prevent and contain an anthrax outbreak?
Officers can use a rapid diagnostic test to confirm or rule out anthrax bacteria. Suspected cases are always confirmed by testing at a veterinary laboratory. In the event of an outbreak, DPI implement a number of control procedures. Affected carcasses are burnt in situ and site decontamination is undertaken. Quarantine and tracing of animals and animal products from affected farms is also conducted. Other animals that are considered at risk in the area are vaccinated because this is an effective way to limit the spread of the disease.
DPI liaises with knackeries, local vets, Australian and local governments, dairy processors and regional emergency services staff to coordinate the response and ensure that all the necessary disinfection is completed.
Are there any preventative measures?
It is difficult to predict or prevent an anthrax outbreak. However, each jurisdiction isprepared to respond to a notification of anthrax and undertake the response in accordance with the nationally agreed response plan. In addition, state and territory agriculture authorities are alert to developments inscientific knowledge and technology that may be applicable in Australia. For example, in November 2007, Victoria investigated new technology for incineration that may help our response to emergency disease situations, including anthrax.
Animal Tracing
Australia keeps track of cattle consigned to knackeries and abbattoirs. The carcasses areidentified with a National Livestock Identification System (NLIS) tag. As well, producers receiving cattle from other properties must register the movement on the NLIS database within seven days of the cattle moving.
What should owners do if they suspect an outbreak and what will happen?
The animal owner/carer, veterinarian, or any other person whose professional work includes managing livestock, such as agents and truck drivers must report any suspected cases of anthrax to their Department of Primary Industries or Agriculture. You can do this by phoning the national Emergency Animal Disease Watch Hotline on 1800 675 888.
Movement of animals and animal products from the farm will be suspended and appropriate samples collected and tested at a laboratory. This can take 12 – 24 hours. If the case occurs on a dairy farm, the dairy factory is advised to suspend collection of milk until the case is investigated. Vet costs will be paid by the DPI. Veterinary practitioners who respond to a request from a producer to check a carcass for anthrax should invoice DPI for the visit as well as the costs associated with testing the carcass for anthrax.
