If asked "What is the greatest current threat to humanity?" you are likely to come up with nuclear war, climate change, over-population but perhaps not antibiotic-resistant bacteria.

Distinguished Professor Nigel French of Massey University would put antimicrobial resistance (AMR) in bacteria up with, if not ahead of, the others.

And at his talk in Whanganui last month, he cited a report published in 2014 that predicted that by 2050 about 10 million people per year would be dying as a result of antimicrobial resistance.

The previous president of the United States pointed out that deaths attributable to AMR would greatly outstrip causes such as cancer and infectious diseases by 2050.

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Antimicrobials kill microbes including bacteria, viruses, protozoa and fungi. Within the main group of antimicrobials are the antibiotics which are active against bacteria. It is important to understand that antibiotics are ineffective against viruses.

French showed the basic mechanics of how antibiotic bacteria developed via a YouTube video. Just type "Watch antibiotic resistance evolve" into the YouTube search box.

In a matter of days, a bacterium evolves from being mostly destroyed by a low concentration of antibiotic into one that can withstand a concentration 1000 times stronger. It should be emphasised that the mutations occurring here would occur anyway (ie, they are not caused by the stronger antibiotic). The more resistant bacteria proliferate because they are no longer competing with those destroyed by the antibiotic.

This effect was also illustrated by a patient in Palmerston North who received treatment for campylobacter infections that had recurred over a period of 10 years.

Samples of each infection had been collected and DNA sequenced. Each time the person received antibiotic treatment, it could be seen that the strain of bacteria developed resistance to that particular antibiotic.

The World Health Organisation has said that each country should develop an action plan. So, what is New Zealand doing about the problem? The most important strands of the national action plan are as follows.

Surveillance and stewardship: This means accurately monitoring antibiotic use and the incidence of development of resistant bacteria strains while making sure their use is appropriate. Prescribing antibiotics for a viral infection will not cure the viral infection and it may facilitate development of resistant bacteria.

Infection prevention and control: At first this seems to be obvious. Washing your hands after going to the toilet, not eating undercooked chicken and other similar simple strategies. There is also a downside to this.

Research has shown a link between under exposure to bacteria in the first years of life (ie, keeping your baby clean) and an increased propensity to allergies and even some forms of cancer in later life. Letting your kids get dirty is good for them up to a point but the tipping point is difficult to define.

In order to achieve these aims New Zealand takes a "One Health" approach. This is an holistic approach that combines human health, animal health and the health of the ecosystem in which we live.

The issues of antibiotic resistance, impacts of environmental pollution, food safety and the emergence of infectious diseases cannot be addressed in isolation.

I recommend you look at the factsheets on the website of the Royal Society of New Zealand to find further information. There are many routes for the transmission of antibiotic resistant organisms and they need to be monitored and controlled.

French looked at the levels of use of antibiotics both for humans and animals across the world and it was evident New Zealand is a high user. The balance is also interesting. The split between animal and human use in New Zealand is roughly 50/50 by amount.

However, there are many times more livestock animals in New Zealand than people. This means that the rate of human use in New Zealand is much higher than for animals. Graphs comparing rates of human and animal use across the world showed New Zealand to be sixth from highest for human use but third from lowest for animal use.

These figures need to be put further into perspective. The biggest users of animal antibiotics are in the more intensive industries of pig and poultry production where they are used to control things such as chlostridial infections which would otherwise cause high mortality in intensively farmed stock.

Within these industries a large percentage of the antibiotic used is Bacitracin. This drug is not critically important as a human antibiotic at the moment. It should also be said that there are moves to reduce its use.

The New Zealand Veterinary Association made the statement (unrealistically in French's opinion) that "by 2030 NZ Inc will not need antibiotics for the maintenance of health and welfare in animals". Unrealistic or not, it does show the determination to reduce antibiotic use in animals.

Research shows that for both animals and humans, greater use of antibiotics results in higher levels of antibiotic resistance. Less clear is the possibility of a link between antibiotic use in food animals and human antibiotic resistance.

There is a correlation for some drug/bug combinations, but this does not apply across the board. This then raises the question of what effect the control of antibiotic use in animals might have on the development of drug-resistant bacteria in humans.

New Zealand has a high rate of zoonotic infections (infections spread from animals to humans). Much of the cause of this is that Kiwis have a lot of contact with animals, both as farm animals and as pets.

Cows in New Zealand produce over 80,000,000 tonnes of poo per year and most of this goes straight onto the land. This means resistant bacteria that have developed in animals can get into the human food chain and then spread from human to human.

In summation, avoidance of infection in the first place and informed stewardship in their use are the short-term strategies for antibiotics. In the longer term, we need to be looking at strategies that are not dependent on the use of antibiotics.

Frank Gibson is a semi-retired teacher of mathematics and physics who has lived in the Whanganui region since 1989.