What does our future hold: will infections continue to dominate?

For a number of months in 2003 SARS occupied the world’s headlines with reports of a growing epidemic of cases and deaths largely concentrated in China. Are we now witnessing a replay of such an event?

The current outbreak of a new strain of coronavirus in Wuhan, China and its rapid spread across China and parts of Asia suggests that we are possibly facing yet another epidemic or pandemic. So far there have been thousands of cases of the disease in China and at least 100 deaths. Like SARS this new virus produces a respiratory infection and is currently spread through droplets.

It is most likely associated with food markets in China and there is now some evidence of it having developed the ability to spread between humans. Quite likely this virus jumped from farm or wild animals and that food markets selling wild animal meat have acted like secondary reservoirs of disease. Like SARS this virus could quite possibly spread from China in a contagious cascading fashion spreading from index cases following well defined routes reflecting the geographical mobility of individuals.

This raises many questions about the control of such a disease in an increasingly interconnected world. Already cases of the virus are beginning to appear around the world. Attempts to control the virus like those faced by SARS are turning into a nightmare and tells us much about facing the spread of viral infections. A critical factor in all of this is how the media presents such infections and the public’s reaction.

Despite the many advances in medicine and public health over the last century infectious diseases remain an important threat to our health and we remain inadequately prepared to deal effectively with viral diseases such as that currently sweeping through China.

An important part of this is our continuing underestimation of the power and resilience of the microbial world and our failure to fully recognise the importance of infectious disease and the role of the biophysical environment.  Today infectious disease accounts for more than 70% of all deaths in tropical developing countries. Even in our world infectious disease continues to play an important part. In the USA for example, it is estimated that at least 48 million people experience a food-borne infection every year.  

The fact that nearly three quarters of all emerging infectious diseases originate in the animal kingdom is still not fully appreciated despite that the fact the Rudolph Virchow first coined the term zoonosis in 1855 drawing our attention to the importance of the biophysical environment. We also continue to believe that we are the dominant species on earth and that we can simply level a magic bullet at infections and continue our dominance.

Nothing could be further from the truth. Infectious diseases are the dominant species with the ability to mutate and adapt to anything we might level at them. There is little doubt that we live in a fragile world and continue to be exposed to regular outbreaks of infectious disease, and there is little doubt that in a highly mobile world where more people than ever before are travelling across international borders new and re-emerging infectious diseases will pose a major threat to global health over the next 50 years. These diseases will continue to endanger Australian and New Zealand citizens at home and abroad as well as threaten the social and political stability of many of the world’s countries.

Add all this to the fact that some infections have never disappeared. Take bubonic plague for an example. Today plague is more geographically widespread than at any time in human history. Almost half the USA is one giant natural reservoir of bubonic plague where the disease is permanently maintained in the burrows of ground living animals. While the disease rarely affects humans, efforts to eliminate plague have proved impossible.

There are many factors responsible for the emergence of new infections and the persistence of older ones. Some are the product of natural processes in the biophysical environment but many are the result of human behaviour. Factors such as population growth, human migration, international travel, wars and political unrest, poverty and changes linked to social and economic development are all of critical importance. So too is vaccine hesitancy and the movement away from regular childhood vaccinations. Important is also the way we continue to intrude upon and modify natural zoonotic reservoirs where infections have been entrenched for centuries.

Climate change also plays an important part. As the atmosphere warms and rainfall patterns change some infectious disease vectors such as mosquitoes expand their geographical distribution into previously unoccupied areas. In Australia the mosquito vector for dengue threatens to do this over the next decade.

Over the last 20 years the world has experienced numerous infectious disease epidemics and pandemics. HIV/AIDS, SARS, Influenza, Avian Flu, Ebola, MERS and Zika to name but a few have all taken their toll causing widespread fear and panic. Our reaction to SARs and Avian Flu suggests what might be ahead with respect to this new Chinese virus.