by Matthew Ball, Virbac Australia
BOTULISM on livestock can have devastating effects for Australian livestock producers, particularly for cattle producers in northern Australia.
Virbac Australia recently co-operated with the Northern Territory Department of Primary Industry and Fisheries and private veterinarians to measure the effectiveness of routine vaccination practices on 15 northern Australian cattle stations. The results provided significant results for cattle producers.
A series of surveys and trials conducted over the last three years has revealed new data that should enable cattle producers to more successfully manage botulism in northern Australia.
Botulism is a severe and often fatal disease of cattle and sheep caused by exposure to a toxin produced by the bacterium clostridium botulinum.
Under favourable conditions, active spores can lead to bacterium growth, and the resulting toxin can kill cattle when they accidentally ingest it.
Virbac Australia technical services manager and practising veterinarian Dr Matthew Ball describes the devastating effects of botulism on livestock.
"Botulism is one of the most lethal toxins on earth, potentially killing thousands of Australian cattle a year,” he said.
"Its spores multiply suddenly, and if toxin from active bacteria gets into the body, it affects the junctions between the muscles and nerves, leading to paralysis, and often death.”
Dr Ball goes on to explain how botulism is a particular problem for cattle in northern Australia.
"The area is known for its low levels of phosphorous - and that deficiency drives cattle to seek phosphorous from other sources, either via parts of a decaying carcass or contaminated bones, in silage or hay, or by directly ingesting spores from soil.”
15 northern Australian cattle stations with over 450 animals were involved in the study, which had been vaccinated with either SingVac 1 Year, SingVac 3 Year or Longrange within the previous 12 months.
The results of this stage one survey found markedly different levels of protection with different vaccines. Surprisingly the survey showed on average only 77 per cent of cattle tested had reached effective protective levels against botulism. However, 83 per cent of animals vaccinated with SingVac were found to have adequate protection levels (with several stations achieving 100 per cent), whilst only 60 per cent of the animals vaccinated with Longrange had adequate protection levels.
The 23 per cent difference between the vaccines was described as "statistically significant” - and that led Virbac Australia to conduct a more detailed stage two trial, to measure the effectiveness of two key botulism vaccines on the same property and in the same conditions and animals.
The trial was conducted on three northern Australia properties, with tests conducted about 180 days after vaccination... and the results provide further evidence that not all vaccines offer the same level of protection.
On one property in the Kimberly, WA, it was found that at 163 days, on average 20 per cent more cattle achieved adequate protection levels from Botulism with SingVac than with Longrange.
Overall, animals vaccinated with SingVac were found to have a much higher average 'titre response' of 0.8 compared to Longrange, which averaged 0.54 - a higher titre response meaning that cattle have higher levels of immunity and are better equipped to fight off a botulism challenge.
In Dr Ball's opinion, it isn't a surprise SingVac's class-leading technology made it perform better in this study.
"SingVac is the only cattle vaccine in Australia to utilise a 'water in oil in water' adjuvant. This unique formulation causes the animal's body to mount a higher immune response against botulism, and to keep building the immune response to a superior level than other 'traditional' vaccines.”
Nevertheless, a range of different factors means that with first-time treatment, 100 per cent protection from botulism is never possible - as Dr Ball describes.
"Issues like the overall health of the animal, as well as the method and thoroughness of vaccine delivery to the animal can all affect its success,” Dr Ball said.
"A vaccine will only work well if the animal's immune system is functioning properly - and that's why it's important to ensure adequate and balanced levels of trace minerals and nutrients, for the normal health and function of immune cells - which are essential for a vaccine to work.”
For Dr Ball, what makes these results even more compelling is the fact that weaners were selected for the trial.
"Weaners have additional difficulties in vaccine response compared to older animals - they're the trickiest to vaccinate successfully because of factors like maternal immunity interference, or additional stresses during weaning at the time of vaccination, which can interfere with a vaccine's efficacy.”
Dr Ball says the importance of an effective botulism vaccination shouldn't be underestimated.
"Put simply, a better vaccine reduces the chance of failure,” he said.
"We know achieving 100 per cent vaccination can be challenging - so you need to use the vaccine type that's got the highest chance of success.”
That higher vaccine success rate translates to some impressive statistics. The findings point to at least a 23 per cent increase in animals with adequate protective titre levels through vaccination with SingVac
"This in-depth study has provided significant results for cattle producers, as Botulism infection can drastically affect both profit and productivity,” Dr Ball said.
"And if you can save the lives of more animals in high risk areas, that's a huge welfare improvement, as well.
"Put simply, a more effective vaccination means fewer deaths and a more successful farm business - facts all worth considering when you're looking at the best way to protect both
your animals and your livelihood.”