By Professor John Crump
American Red Cross volunteers carry a Spanish flu victim, 1919. Image: British Red Cross
The prediction of future risks is fraught and often falls short. In 2005, the Czech-Canadian scientist and policy analyst Vaclav Smil attempted to forecast major hazards that could result in rapid mass human casualties with disruption of the global economic system, termed ‘fatal discontinuities’, over the coming 50 years. He identified hazards by looking back at human pre-history and history to identify the impact and frequency of past ‘fatal discontinuities’, taking the view that past events are probably the most reliable predictors of future events.
Taking this approach, Smil projected that an infectious disease pandemic such as influenza, killing tens to hundreds of millions of people, is highly probable in the coming 50 years. In fact, it is more likely and with more fatalities than mega-wars (which are wars involving multiple major blocks of the world), massive volcanic eruptions with associated tsunamis, and large asteroid impacts.
Disease drivers
Furthermore, there are reasons to believe that history may underestimate the future risk for infectious diseases pandemics because of changes associated with the modern world. These changes include those in demographics and behaviour, environmental change and land-use change, breakdown of public health measures, microbial adaptation and change, international travel and commerce, and changes in technology and industry.
These have developed in parallel with increases in host susceptibility to infection; the emergence of new diseases, for example, from human encroachment on new microbial ecosystems, and increases in disease transmission such as through crowding and international travel.
The most recent infectious disease problem causing a ‘fatal discontinuity’ was pandemic influenza from 1918 to 1920. This event is estimated to have killed 50m to 100m people worldwide, or 3%-5% of the human population at the time. This pandemic was unusual in that it predominantly killed healthy young adults rather than the young and the elderly. Global spread was almost certainly facilitated by troop movements associated with the First World War.
We know that influenza viruses periodically reassert to cause global pandemics, and so influenza remains one of the main infectious diseases risks.
Health regulations
On 16 November 2002, an outbreak of a viral respiratory infection that came to be known as severe acute respiratory syndrome (SARS) began in the Guangdong province of China. Early in the epidemic, the Peoples Republic of China discouraged its press from reporting on SARS and lagged in reporting the situation to the World Health Organization (WHO), delaying the initial response. Initially, it did not provide information for Chinese provinces other than Guangdong.
Eventually China registered almost 1,500 SARS cases, with travel-associated outbreaks in Hong Kong, Taiwan, Canada, and the United States. At the time there was considerable concern about whether the global health response could get ahead of the rapid spread of SARS epidemic and whether or not it would be contained.
The SARS experience was a wake-up call that led to the revision in 2005 of the outdated 1969 International Health Regulations (IHR). It was recognised that a new legal framework was needed to detect and respond to modern public health risks and emergencies. In brief, the revised IHR required member states to notify and verify events that may constitute public health emergency of international concern in their own and other territories, meet minimum standards for national surveillance and response, and implement health measures at borders.
So how has the global health community done since the 2005 revision of the IHR?
Unfortunately, the report card is not looking fantastic. Middle East Respiratory Syndrome (MERS), a viral respiratory illness that is thought to be new to humans, was first reported in Saudi Arabia in 2012. There have been widely publicised concerns about delayed reporting and under-reporting by Saudi officials. Three years on, the mode of transmission although understood in broad terms, has not been clearly elucidated or publicised. Consequently data critical for control are weaker than they could be.
Ebola virus disease
Health centre in Sierra Leone during the 2014/15 Ebola epidemic. Image: EC/ECHO/Cyprient Fabre.
More recently, the largest Ebola virus disease outbreak in history began in 2014. In addition to the challenges associated with the outbreak occurring in fragile states with weak health systems, WHO has been criticised for being slow to respond to the outbreak, highlighting that many lives could have been done if more had been done earlier.
With the shortcomings in infectious disease epidemic control since 2005 in mind, the Global Health Security Agenda was launched in 2014. This is a multidisciplinary effort involving governments, international organisations, and public and private stakeholders to accelerate progress toward a world safe and secure from infectious disease threats and to promote global health security as an international security priority. The global health security agenda recognises that, while the revisions to the IHR were appropriate and necessary, considerable resources are needed to implement them in all states and to coordinate a global response to a major disease threat.
So where to from here for global health security? There is a strong case that modern circumstances favour the emergence of epidemics that threaten many or all humans. Amendments to the IHR have strengthened the mandate to detect and report.
However, infrastructure in fragile states prevents detection and investigation and political agendas may delay reporting. Furthermore, WHO has struggled to respond quickly to large and complex outbreaks. There is now considerable new investment in global health security. Time will tell what impact it has, but hopefully the world is keeping up with the growing risk of a ‘fatal discontinuity’.
Professor John Crump is the inaugural McKinlay Chair of Global Health at the Centre for International Health, Dunedin School of Medicine, University of Otago.