10:26am Friday 22 September 2017

Bad bugs: Pandemics

Professor Nigel French.

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 before – 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 getting 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, which was recognised by the United States Center for Disease Control and Prevention when it awarded New Zealand a five-year contract to study influenza and how it spreads.

The SHIVERS (Southern Hemisphere Influenza Vaccine Effectiveness Research and Surveillance) project 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. Deaths would be inevitable – the Spanish Flu, for example, had a fatality rate of about 2.5 per cent.

In a 2006 discussion document anticipating the impact of a serious avian influenza pandemic, Treasury estimated that 40 per cent of the population would become infected, with a fatality rate of two per cent. On top of that it estimated another 40 per cent of the workforce would take time off due to a fear of infection or to care for others. With influenza, the wave of infection occurs over an eight-week period, with the greatest infection rates in the third, fourth and fifth weeks. 

The subsequent shutting down of schools and workplaces, along with a sharp decline in tourism and retail activity could result in significant economic impact – Treasury estimated a five to 10 per cent reduction in GDP in the year of the outbreak.

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 even begin to produce a vaccine. Until a pandemic is unfolding it is impossible to know the exact nature of the threat so the ability to respond quickly in a flexible way is key. 

Those studying infectious disease know that 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. 

Considerable investment in scientific capability is needed if New Zealand is to stay one step ahead of the bugs, to develop new technologies that will mitigate the effects of our own impacts on their evolution and emergence.

We are as well prepared as any developed country for a potential pandemic but our current investment in research is falling behind other nations. 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.
Massey University


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