Animal antibiotic sales down
Total sales of veterinary and horticultural antibiotics in New Zealand have decreased for a fifth year in a row, dropping by 23% in 2022.
During the recent World Antibiotic Awareness Week (Nov 12-18) the animal health industry looked at ways to redefine antibiotic use by reducing the need for antibiotics through prevention, innovation and collaboration.
Because few new types of antibiotics are being developed, the ones we have must be used carefully so that bacteria are less likely to become resistant to them.
Antibiotic use in New Zealand production animals is estimated to be the third-lowest in the world, but industry, farmers and regulators still need to work to preserve this precious resource.
Globally, resistance to antibiotics threatens the health of humans and animals. If trends continue, it could cost the lives of 10 million people by 2050.
The animal health sector is responding by helping prevent disease in the first place and reducing the need for antibiotics. This is done by vaccination, probiotics and targeted viral tools.
Vaccinations protect animals from contracting a disease. They are like a boot camp for the body’s immune system – preparing it to create the right defences for when it comes under attack.
Often made of a ‘dead’ or weakened version of a disease, vaccines give the body a practice run at producing the right antibodies to fight a particular microbe (infection). They may also be made of antigens -- the proteins on the outside of microbes.
While the weakened disease won’t cause an infection, the body will identify it as an enemy it needs to attack. Once the battle is over, the immune system will retain this knowledge in ‘memory’ cells.
This means that if the microbe attacks in the future, the body’s immune system will ‘remember’ how to produce the right antibodies to fight it off. Crucially, it will be able to produce these fast enough to avoid a serious health threat -- avoiding the use of antimicrobials.
Today, a variety of vaccines are available for farm animals and pets, helping to prevent and reduce the spread of infectious diseases.
Scientists are also looking at developing new vaccines to help overcome the barriers of associated labour costs and potential impacts on the immune system.
Probiotics, often referred to as ‘good bacteria’, are increasingly recognised as an effective feed additive to ease the use of antibiotics. This benefits gut health and animal wellbeing. The gut is made up of a complex mixture of bacteria, so when the balance is disrupted, the animal can become sick, leading to reduced productivity.
Probiotics are live bacteria. They leave fewer resources available to unfriendly bacteria so they cannot cause disease. By helping maintain a balance of good and bad bacteria, probiotics are believed to improve the animal’s health and performance. Scientists are still investigating their effectiveness.
Vaccines, probiotics and other tools are effective at preventing disease. Nevertheless bacterial illness can still occur and antibiotics are usually the only available treatment.
Researchers are exploring a ground-breaking treatment called bacteriophages. Sometimes known simply as phages, this is a virus that infects and kills bacteria. The name ‘bacteriophage’ literally means ‘bacteria eater’. Phages work by recognising and attaching to a bacterial cell then injecting it with their own DNA. Once the DNA is inside, the nutrients and components of the bacteria are used to form new copies of the phage. These hungry offspring then break out by releasing chemicals to destroy the host bacteria and go on to look for other bacteria to infect and feed on.
Experimentally, phage therapy shows promise in treating bacterial infection in animals. When used in chickens infected with E.coli, bacteriophages protect them from respiratory disease. But phages have limitations and their efficacy is uncertain in many situations.
Although these alternatives provide an extra lifeline, antibiotics allow us to treat the most serious antimicrobial infections and keep our animals healthy. So it is vital that the animal health industry and regulators keep working together with farmers to make sure that antibiotics continue their life-saving work.
• Mark Ross is chief executive of Agcarm, the industry association for companies that manufacture and distribute crop protection and animal health products.
