Anthrax explodes in an Australian summer

Anthrax occurred on 83 properties in an area of north central Victoria between 26 January and 26 March in the summer of 1997. Anthrax had not been recorded in the outbreak area since records were initiated in 1914, although anthrax did occur in the general area in the 1880s to 1890s. Standard Australian control measures were applied to the properties, including quarantine, tracing movements of animals on and off affected properties, secure disposal of carcases by burning, enhanced surveillance of stock generally in the area and the use of local disaster control procedures including an alert of health authorities. As affected property numbers began to increase dramatically from 8 February, it was decided to use blanket area vaccination to control the disease. By 26 February, the epidemic curve had returned to the base line and a buffer vaccination zone of 457 farms holding 78,649 cattle was formed by early March 1997. Between 26 January and 26 March when the outbreak was declared over, 202 cattle and 4 sheep were confirmed to have died of anthrax. Between 27 March and early November a further 26 cattle were confirmed as dying due to anthrax and 14 of these had not had previous vaccination, including four young calves and one horse. One new property within the vaccination buffer zone had an anthrax case in a cow in early November 1997. By mid-November 1997, all previously infected and all neighbouring properties within 1 km were compulsorily re-vaccinated, as were all calves when two months of age and all introduced cattle. In 1998, only two confirmed cases of anthrax were diagnosed; both were vaccinated calves on farms which had had multiple cases during the outbreak. The public reaction and attention fueled by unprecedented media attention led to intense international scrutiny from countries where anthrax is a particular zoonotic problem. Very strong representations had to be made about the safety of livestock and livestock products that came from Victoria. This event has demonstrated that there is a need to review OIE and other requirements and recommendations covering anthrax where strict restrictions are placed on livestock and livestock products to protect livestock and human populations against anthrax infection.