It's becoming increasingly difficult to battle the bugs that make us sick as highly contagious pathogens evolve more quickly, and it is partly our fault, writes Professor Nigel French.
There is an arms race occurring - one that is largely hidden, but one that is vital for us to win. It is the battle between humans and the bugs that make us sick.
In recent years we have seen the emergence of a growing number of zoonoses - infectious diseases that can move between animals and humans - and other highly contagious pathogens. These pathogens are evolving more quickly than ever - in fact we are forcing them to develop because of the things we do.
Anti-bacterial and anti-viral drugs are driving the evolution of new, resistant strains. Urbanisation, global trade and travel, climate change and farming practices mean pathogens spread now more easily and have a greater geographical range.
Historically, we have been able to keep pace with these developments. We are smart enough to develop new technologies: we have discovered new antibiotics, developed vaccines, found new surveillance tools that enable us to get ahead of the epidemic curve and put measures in place to prevent widespread infection occurring.
But it is becoming increasingly difficult.
How concerned should we be about a serious pandemic - a disease that is both highly infectious and has a high rate of mortality? If we look back at the 20th century there were two pandemics that killed large numbers of people: the Spanish Flu of 1918 and the HIV/AIDS pandemic of the 1980s. There is every reason to believe the world could experience a similar number of serious outbreaks in the 21st century.
How well we respond will depend on a number of factors. If a new virulent strain of influenza was to develop during the southern hemisphere winter, New Zealand could be one of the first countries to be exposed. Fortunately, we have some expertise in dealing with influenza.
The SHIVERS (Southern Hemisphere Influenza Vaccine Effectiveness Research and Surveillance) project, a five year Kiwi study funded by the US Center for Disease Control and Prevention, has just completed its second winter of surveillance and will be instrumental in improving the methods used for managing influenza outbreaks globally in the future.
New tools are also emerging to help us find out more about pathogen evolution. We have begun the process of sequencing the full genomes of large numbers of pathogens to discover the real-time patterns of change that happen throughout an epidemic. This gives us a fantastic insight into how pathogens spread and means we can identify the source of infection much faster and turn the taps off more quickly.
But even with all the improvements in vaccines, anti-virals and surveillance methods of the past 100 years, New Zealand's population growth since the 1918 Spanish Flu outbreak means it is still possible a pandemic influenza would overwhelm our medical system.
A 2006 Treasury document predicted 40 per cent of the population would become infected, with a fatality rate of two per cent. The shutting down of schools and workplaces, plus tourism effects, would mean a five to 10% drop in GDP that year.
The situation will be even more serious if the disease is something entirely new, as the HIV/AIDS virus was, and scientists have to go through the process of pathogen discovery before they can produce a vaccine.
To truly understand how pathogens move we need to break down the barriers between human and animal health. This new 'one health' approach brings together medical and veterinary expertise to address transmission cycles that involve both people and animals.
Staying ahead of pathogens as they evolve is vital for our health, our food and our economy - if our technology can't keep ahead of our own demographic changes we will be in serious trouble.
Professor Nigel French is the director of the Infectious Disease Research Centre at Massey University.