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Anthrax causes dozens of cattle deaths near St George – UPDATED

James Nason, 08/03/2017

Dozens of cattle have died from Anthrax on a grazing property in South Western Queensland.

A private veterinarian called to the property west of St George in response to the sudden deaths of about 80 of cows and calves last Friday quickly diagnosed Anthrax as the likely cause.

Biosecurity Queensland was contacted and immediately initiated a “control and contain” procedure, placing the infected property under quarantine and restricting the movement of people, stock and vehicles in and out.

It is understood that as many as 100 cattle may now have died as a result of the outbreak.

Health authorities have stressed that risk of human exposure to Anthrax from animals is regarded as “very low”.

Biosecurity officials and cattle industry leaders have also emphasised that Anthrax is a naturally occurring bacteria that occurs sporadically in Australia, with a small number of cases each year.

Outbreaks in Australia can vary from sporadic cases to epidemic proportions depending on soil, climate and degree of contamination.

NSW Anthrax Belt

The Anthrax Belt – for the last 50 years almost all cases of anthrax in NSW have occurred within the highlighted region termed the ‘anthrax belt’. Much fewer cases have occurred in Qld. St George is located about 100km north of the NSW border, and 200km north west of Moree, on the upper right of the yellow band on this map.

Anthrax occurs most commonly in New South Wales in what is known as the ‘Anthrax belt’ (from Moree and Walgett down to the Victorian border from Corowa to Deniliquin).

There was one isolated incident in Queensland near Shoalwater Bay in 1994. There have been cases of anthrax near Dirranbandi in February 2002, and a further occurrence near Wandoan in 2002, originating from Dirranbandi.

Just three days ago Anthrax was confirmed as the cause of death in at least one sheep on a property at Swan Hill in Victoria (more details on Sheep Central here).

Where does Anthrax come from?

Biosecurity officials say grazing animals become infected by eating the naturally-occuring spores of Anthrax while feeding. The spores germinate into the active form of the bacterium and begin to multiply rapidly once inside the animal.

Within a few days the animal’s immune system is overwhelmed and masses of bacteria and their toxins are released into the bloodstream causing sudden death.

Carcases of animals that have died from Anthrax are full of infectious bacteria. A feature of anthrax infection is failure of the blood to clot, so after death blood and body fluids ooze from body orifices and sites of predation on an infected carcase.

These fluids are loaded with Anthrax bacteria which form resistant spores as soon as they are exposed to the environment outside the carcase.

Spores are the ‘resting’ form of the anthrax bacterium. They are inert with a tough shell which makes them highly resistant to environmental factors such as heat, cold, ultraviolet radiation, dryness and other factors which would kill the bacterium in its ‘active’ form.

Spores can survive in the soil for many years, up to 80 years in some cases, waiting for conditions to be suitable for them to gain entry to an animal and cause disease.

Graded track may have distributed spores

On the St George property, a track was recently graded in a paddock where the outbreak occurred. It is believed this may have disturbed contaminated soil and distributed soil containing the bacteria. After rainfall triggered a green shoot on the track, cattle foraging the green pick on the ground may have picked up the Anthrax spores.

Remaining cattle on the property have been mustered to separate them from the contaminated area. Biosecurity Queensland has commenced a vaccination program for the remaining cattle.

Anthrax has an incubation period of 10 days after exposure. The quarantine restrictions will remain in place for at least 20 days to ensure all infections are identified.

Disposal and decontamination procedures for the deceased animals are also now underway. It is understood the carcases must be completely burned to ash in a very hot fire to destroy the Anthrax bacterium and eliminate the risk of further environmental contamination.

“It has been well contained and managed”

AgForce cattle president Bim Struss was part of a group that received a briefing on Tuesday from Queensland’s Chief Veterinary Officer Allison Crook.

He said the incursion had been very well managed, from the property owner who addressed the situation quickly to the veterinarian who swiftly diagnosed Anthrax and Biosecurity Queensland which also acted immediately.

“We need to be very careful we don’t panic our markets,” Mr Struss said.

“It is contained, it is well managed, fortunately the vet who attended them was on the ball and diagnosed Anthrax very quickly.

“It is not contagious, there is a very low risk, the only way a beast can really pick it up is eating or picking up the spores out of the ground.”

In a statement released on Tuesday Queensland Chief biosecurity officer Dr Jim Thompson commended the veterinarian and property owner for their quick response, which he said had helped Biosecurity Queensland to minimise the risk to the local industry.

Health risk to humans very low

Queensland Chief Health Officer Dr Jeannette Young said in a statement that the risk of human exposure to anthrax from animals is generally regarded as very low.

“Public health authorities are in contact with people on the property and the veterinarian,” said Dr Young.

“The veterinarian used appropriate personal protective equipment and eight people, including family and a farm worker, did not have any contact with the dead animals.”

Livestock biosecurity fund

In recent years Queensland has been working to develop a State Based livestock biosecurity fund to help producers manage financial losses caused by biosecurity events.

South Australia and Western Australia use a voluntary levy to resource their fund, and Victoria has a compulsory state-based levy (more details here)

It is understood Queensland is considering a system where cattle producers would make voluntary contributions in return for being able to receive financial compensation for losses in the event of a biosecurity issue.

Mr Struss told Beef Central that work to finalise the details of the biosecurity fund, such as what it would cover, and how it would be levied, is still underway, but the concept has support from the current Queensland Government and an outcome is likely.

NT disease investigation update

In other animal disease developments, a Northern Territory Animal Biosecurity spokesman said investigations were ongoing into the cause of a number of cattle deaths in the Katherine area recently.

No specific disease cause had been identified in the episode of young cattle deaths being investigated by NT vets.Typical northern summer worm burdens and the fact the young cattle had been dipped, might prove to be underlying causes for the losses, Beef Central was told. Coccidiosis infection may also have played a role in young cattle at a vulnerable stage of life.

Beef Central published this article on 2 March, discussing an animal disease investigation near Katherine, and a separate case where eight northern pastoral company staff presented sick, and were tested at a Darwin hospital.
At the time, some felt the two episodes might be related. Leptospirosis was suspected by some as a possible cause – influenced in part by the Territory’s extreme wet-season this year – but has since been ruled out in both the human health and animal mortality cases.

 

Producers who suspect they may have anthrax in their stock or are experiencing sudden, unexplained stock deaths on their properties, should contact their local government veterinary officer immediately or call the Emergency Animal Disease Watch Hotline 1800 675 888. Animal Health Australia plays an important role by coordinating Australia’s anthrax vaccine bank which is to be used in the event of a major outbreak.

For more information about anthrax and its effect on animals visit these links:

Queensland Department of Agriculture – Anthrax disease fact sheet

Animal Health Australia – “Vigilance protects from Anthrax”

Animal Health Australia – AUSVETPLAN

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