#17,751
Twelve years, and more than 12,000 blog entries ago, I wrote a piece called The Third Epidemiological Transition, based on the works of the now late (May 22, 1936 - May 15, 2014) anthropologist and researcher George Armelagos of Emory University.
The gist of his theory - which he first published in the mid-1990s - was that since the mid-1970s the world had entered into an age of newly emerging infectious diseases, re-emerging diseases and a rise in antimicrobial resistant pathogens.
Just to name a few (see UK HAIRS Report: Emerging Infections - How And Why They Arise).
Emerging infectious diseases are considered such an important public health threat that the CDC maintains as special division – NCEZID (National Center for Emerging and Zoonotic Infectious Diseases) – to deal with them, and 29 years ago the CDC established the EID Journal dedicated to research on emerging infectious diseases.
More recently, in In 2014, in Emerging zoonotic viral diseases L.-F. Wang (1, 2) * & G. Crameri wrote:
The last 30 years have seen a rise in emerging infectious diseases in humans and of these over 70% are zoonotic (2, 3). Zoonotic infections are not new. They have always featured among the wide range of human diseases and most, e.g. anthrax, tuberculosis, plague, yellow fever and influenza, have come from domestic animals, poultry and livestock. However, with changes in the environment, human behaviour and habitat, increasingly these infections are emerging from wildlife species.
And just over two years ago, in PNAS Research: Intensity and Frequency of Extreme Novel Epidemics, researchers calculated that the risks of seeing another COVID-level pandemic in any given year is roughly 2% . . . and suggest that rate may increase 3-fold over the next few decades.
As unpalatable as the message might be - we are living in an age of increasing pandemics - and the frequency and impact of global health crises are only expected to rise in the years ahead.
Today we've got a research article, published in the BMJ Global Health journal, that examines the rise of zoonotic disease spillover events (and resultant deaths) since the early 1960s, and concludes their rate has steadily increased over time.
Should those trends continue, they suggest `. . . these pathogens to cause four times the number of spillover events and 12 times the number of deaths in 2050, compared with 2020.'
Due to its length, I've only posted the Abstract and a few excerpts. Follow the link to read the report in its entirety. I'll have a brief postscript when you return.
Amanda Jean Meadows, Nicole Stephenson, Nita K. Madhav, Ben Oppenheim Correspondence to Dr Amanda Jean Meadows; ameadows@ginkgobioworks.com
Abstract
The COVID-19 pandemic has focused attention on patterns of infectious disease spillover. Climate and land-use changes are predicted to increase the frequency of zoonotic spillover events, which have been the cause of most modern epidemics. Characterising historical trends in zoonotic spillover can provide insights into the expected frequency and severity of future epidemics, but historical epidemiological data remains largely fragmented and difficult to analyse. We utilised our extensive epidemiological database to analyse a specific subset of high-consequence zoonotic spillover events for trends in the annual frequency and severity of outbreaks.
Our analysis, which excludes the ongoing SARS-CoV-2 pandemic, shows that the number of spillover events and reported deaths have been increasing by 4.98% (confidence interval [CI]95% [3.22%; 6.76%]) and 8.7% (CI 95% [4.06%; 13.62%]) annually, respectively. This trend can be altered by concerted global efforts to improve our capacity to prevent and contain outbreaks. Such efforts are needed to address this large and growing risk to global health.
WHAT IS ALREADY KNOWN ON THIS TOPIC
- The devastating impact of contemporary zoonotic spillover-driven epidemics, such as COVID, on human health and livelihoods has highlighted the need to better understand trends in infectious disease spillover.
- Although the frequency of spillover-driven epidemics is predicted to increase as a result of human-driven climate and environmental change, the magnitude of its implications for global health in the future is difficult to characterise given the limited empirical data on the frequency of zoonotic spillover, and its variability over time.
WHAT THIS STUDY ADDS
- This study draws on an extensive epidemiological database to examine a specific subset of zoonotic spillover events for trends in the frequency and severity of outbreaks.
- We find the number of outbreaks and deaths caused collectively by this subset of pathogens (SARS Coronavirus 1, Filoviruses, Machupo virus, and Nipah virus) have been increasing at an exponential rate from 1963 to 2019.
- If the trend observed in this study continues, we would expect these pathogens to cause four times the number of spillover events and 12 times the number of deaths in 2050, compared with 2020.
HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY
- This study suggests the series of recent impactful spillover-driven epidemics are not random anomalies, but follow a multi-decade trend in which epidemics have become both larger and more frequent.
- These findings provide additional evidence that concerted global efforts to improve our capacity to prevent and contain outbreaks are urgently needed to address this large and growing risk to global health.
(SNIP)
Discussion
We found the number of outbreaks and deaths caused by SARS Coronavirus 1, Filoviruses, Machupo virus, and Nipah virus have been increasing at an exponential rate from 1963 to 2019. This finding supports other studies that have found significant increases in the frequency of emerging infectious disease outbreaks,1 8 16 and further suggests that outbreaks are becoming more severe. If the trend we observe in this study continues, we would expect to see these pathogens cause four times the number of spillover events and 12 times the number of deaths in 2050, compared with 2020. We believe this is a conservative estimate for two main reasons: 1) we applied strict inclusion criteria for pathogens in this analysis, resulting in a trend that is less likely to be an artefact of advances in surveillance and detection capacity over the study period; and 2) we omitted the ongoing COVID-19 pandemic, which is several orders of magnitude larger than other events, from the trend analysis (see online supplemental data).
Our evaluation of the historical evidence suggests that the series of recent epidemics sparked by zoonotic spillover are not an aberration or random cluster, but follow a multi-decade trend in which spillover-driven epidemics have become both larger and more frequent. The continuation of this trend would represent a potentially large increase in global infectious disease risk and burden in terms of loss to human health and livelihoods. However, actions can be taken to disrupt this trend, including by rallying global efforts to improve capacity to prevent and contain outbreaks. Recent proposals have ranged widely, from establishing systems for disaster risk financing to fund response measures;17 creating an intergovernmental panel on pandemic risk to quantify, track, and assess risk over time;18 addressing the drivers of pandemic risk, including deforestation and climate change;5 6 and advancing the technology and infrastructure needed to detect and respond to public health threats19; including surveillance programmes at key sentinel nodes, using a mixture of active and passive surveillance modalities and tools.
Some of these proposals, particularly in the area of advancing infrastructure and technology, have been successfully implemented in response to COVID-19. For example, rapid development of messenger RNA vaccines,20 21 implementation of focused surveillance at key travel hubs22 and congregate settings such as schools and universities23 using passive wastewater testing and active testing, and genomic surveillance to detect emerging variants24 have all demonstrated immense value in improving resiliency to public health threats. The ultimate package of measures to support global prevention, preparedness, and resilience is not yet clear. What is clear, however, from the historical trends, is that urgent action is needed to address a large and growing risk to global health.
While the future is obviously unknowable, the historical trends are both unmistakable and compelling.
When you cram 8 billion people onto an increasingly crowded world, and greatly increase both the speed and accessibility of international travel - viruses that once remained local, and often burned themselves out - can now spread globally in a matter of days.
Toss in the added pressures of climate change, expanding antimicrobial resistance, growing food insecurity, and an increasing number of wars and civil unrest, and it doesn't take a Nostradamus to see that the world has got some serious challenges ahead.
Challenges we can meet - or at least mitigate - but only if we accept that they will come, and prepare for them in advance.
Sadly, the recent dismantling of our global surveillance, reporting, and response systems following the declaration of `victory' over COVID suggests we haven't learned the primary lesson from COVID.
That if it happened once, it can happen again.
While you can't consider it `good news', based on historical trends, it seems likely we'll have many more opportunities to learn this crucial lesson in the years ahead.
