Two properties remain under quarantine in northern New South Wales as investigations continue into an anthrax outbreak that killed 37 cattle earlier this month.
The NSW Department of Primary Industries said yesterday that there had been no reports of anthrax on either Moree-district property since March 9, and now believe the outbreak has been contained.
The carcases of the dead cattle have been burned and all remaining cattle have been vaccinated.
Antrax is an acute disease caused by infection from bacterium spores that exist within soil, and usually occurs when long-buried bacteria is exposed by heavy rainfall or earthmoving activities such as road or channel building.
The disease occurs very suddenly in cattle and sheep, with affected animals often found dead despite having shown no previous signs of illness.
Most outbreaks occur within Gippsland region of eastern Victoria and the 'anthrax belt' which extends from the northern area of Victoria, through to the central pastoralgrazing areas of New South Wales.
Dr David Beggs, a lecturer in cattle in the Faculty of Veterinary Science at the University of Melbourne, said the current outbreak did not ring alarm bells from a human health point of view.
“Anthrax is a worry because the spores last a long time, possibly hundreds of years, and it can infect people.
“That said, antibiotics are very effective, and we’ve had a vaccine since Louis Pasteur invented it in 1881.
“Anthrax spreads by animals or people coming in contact with spores, which are mostly released by dead animals but can remain in the ground for years.
“It doesn’t spread like an infectious disease between people and/or animals.
“Because of this, we can successfully contain the disease through a combination of carcass disposal, quarantine and vaccination. Australia has no anthrax to speak of at the moment and because of that, we call even a single case an outbreak.
Dr Beggs said Australia had an excellent, nationally agreed plan of action for when biosecurity issues such as anthrax occurred, known as AUSVETPLAN.
Professor Julian Rood, a professor of Microbiology in the Department of Microbiology at Monash University said reports of Anthrax outbreaks tended to be reported every few years in various regions of NSW and Victoria.
He said there were a couple of reasons why the anthrax bacterium is dangerous.
“The primary reason is that it makes a powerful toxin called anthrax toxin. The effects of this toxin are the primary cause of disease.
“Secondly, it also makes a very resistant form of the bacterium that is called a spore.
“The spore form is able to survive adverse environmental conditions – so it can survive in the soil for long periods of time up to decades.
“So, you can have an outbreak of disease, the spores can enter the soil and then many many years later the spores can infect another animal and make that animal sick. That is usually the major mechanism of spread in cattle, the animals pick up the spores from the soil.
He said the main risk to humans in such cases emanated from handling tissues or material from an infected animal.
“There is a risk of skin infection from handling hides or handling infected tissues or handling, for example, wool from infected sheep.
“In fact the skin form of the disease used to be called “wool sorters disease” probably a century ago.
“So humans can pick up the disease from infected cattle by handling infected material.
“But there are various forms of the disease in humans.
“The most common form in humans from infected cattle is known as the cutaneous form of the disease – or the skin form of the disease. Importantly the disease does not spread from person to person.
“This is also quite different from the systemic form of the disease that was an issue during the ‘anthrax in the mail’ problems in the US some years ago. This inhalation form of anthrax is much more dangerous and quite different to the situation here.”