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Ebola – the next move?

Ebola is playing a deadly game on a microbial board

30 August 2014

9:00 AM

30 August 2014

9:00 AM

Ebola is not the last major epidemic we will experience in the endless game of chess we are forced to play with the microbial world where we seem destined to always play black and be one move behind. This year has seen the emergence of the deadliest outbreak of ebola the world has ever seen and so far the virus has ravaged parts of Guinea, Liberia and Sierra Leone. The disease is also showing signs of spreading further with cases now beginning to appear in Nigeria and perhaps further afield. So far Northern Hemisphere experts have tended to downplay the significance of the epidemic claiming that the disease does not spread easily between people and the chances of a major outbreak in countries like the USA are remote. But ebola is simply the latest in a long-running battle that we wage with the microbial world and all countries including Australia and New Zealand remain vulnerable to future epidemics and pandemics.

In many ways SARS was a wake-up call to a world which seemed to believe that apart from seasonal flu, epidemics of infectious disease were a thing of the past. SARS virtually came out of the blue and produced more than 8,000 cases with a mortality rate of more than 10% including more than 50% for people aged over 50. It produced an extraordinary reaction of public hysteria, fear and panic which totally overwhelmed the simple number of cases and deaths and saw the re-emergence of centuries old containment procedures of quarantine, isolation, cleansing and scavenging. It also produced an epidemic of finger-pointing and blame labeling as people searched for scapegoats. While SARS did not blow up into a world pandemic the virus was not eliminated but simply became quiescent, perhaps waiting its chance to re-emerge in a slightly different form. Since then the world has experienced Avian and Swine Flu as well as epidemics of dengue and MARS (Massive Acute Respiratory Syndrome), not to mention rapidly increasing antibiotic resistance and the re-emergence of many childhood infections. But why should we be surprised. Microbes dominate our world and have become highly skilled in adapting to their host’s environment. In this chess game we seem always to be one move behind as bacteria and viruses mutate, jump species, seek new hosts and eventually threaten us. They also seem to be highly adept at genetic mutation and in leaping from one species to another, often producing new disease variants en route. Take bats for example, said to be responsible for the current ebola outbreak. They may for example, defecate on a local piggery or chicken farm and as such animals are excellent viral blenders, the resulting microbe may jump to the local farmer. We also seem loathe admitting that many long-established infections are still with us and that we can really do little about them. Bubonic Plague provides a good example. Today the disease is geographically more widespread than at any time in history. Natural reservoirs of plague exist throughout much of the Western USA, as well in Southern Africa, Asia and parts of Latin America. A classic zoonosis or animal disease, plague is permanently maintained in the micro-climate of the burrows of small ground-living animals where it adapts perfectly to their lifestyle. The disease rarely affects us, but every now and again a virulent strain such as pneumonic plague emerges, spreading rapidly. What can we do about it? Very little it seems.

In some ways our world is lagging when it comes to infectious disease control. Look how quickly the 1918-19 Influenza pandemic encircled the world, and today we live in a far more interconnected, mobile and interdependent world. No place on earth is more than an 8 hour jet flight from anywhere else and the numbers of people regularly on the move, whether refugees, business people or holidaymakers, has swollen to extraordinary levels. All this greatly increases our vulnerability, particularly when more people are now visiting more remote locations in Africa, Asia and Latin America. Add this to the expansion of towns and cities into former agricultural and forestlands throughout the developing world as well as the regular intrusion upon long established natural disease reservoirs, and there is little doubt that as far as infectious disease is concerned, we live in a highly complex yet messy world. In many ways we have added to this mess by our continued overuse of antibiotics, which has resulted in the rapid development of antibiotic resistance among a host of infections. Currently, in many developed countries such as Australia, childhood infections have also reared their head despite the existence of defensive vaccination programs. Human behavior rules the roost. People simply refuse for a variety of reasons to have their children vaccinated. A good example of this is pertussis or whooping cough in Australia. Despite the fact that there is a vaccine available for children, since 2010 there have been more than 113,000 cases of the disease, when there should have been very few, if any.

There is little doubt that our detection and response measures to infectious disease are much better today than ever before, but our ability to contain the spread of pandemics still leaves much to be desired. And just how good are we at understanding the human reaction to such events and ‘managing’ the hysteria, fear and panic that often results? Not very good at all I fear.

Currently ebola seems to be largely a West African issue. But just think what might happen if ebola and the influenza virus somehow interacted and the resulting infection spread like the common cold. What a frightening scenario that might produce.

The control of infectious disease remains a complex issue for the 21st century and while many believe that we will simply come up with a single effective drug, the fact remains that given the microbial world’s ability to adapt to such things; we will always remain one move behind and for some looking at the possibility of checkmate.

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Peter Curson is Professor of Population & Security at the University of Sydney.

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