Photo Credit- CDC
The reality of life in this second decade of the 21st century is that disease threats that once were local, can now spread globally in a matter of hours or days. Vast oceans and prolonged travel times no longer protect us against infected travelers crossing borders.
And despite the media hype over airport screening, we have no technology that can realistically, or reliably detect infected individuals and prevent them from entering a country (see Head ‘Em Off At The Passenger Gate?).
As our ability to transport diseases rapidly to any corner of the globe has increased, so has the number and variety of emerging infectious diseases. Something that was foretold two decades ago by anthropologist and researcher George Armelagos of Emory University, which I described in considerable detail in The Third Epidemiological Transition.
According to Dr. Armelagos, the Third Epidemiological Transition began in the late 1970s or early 1980s, and is hallmarked by newly emerging infectious diseases, re-emerging diseases carried over from the 2nd transition, and a rise in antimicrobial resistant pathogens.
When you combine those factors with an increasingly mobile global population of about 7 billion people, and huge increases in the number of animals being raised for food consumption (often in environments conducive to the spread of diseases), and you have a recipe for explosive growth in diseases.
In a 2010 paper, Armelagos along with Kristin Harper, updated his original paper. Both papers are well worth reading.
Int J Environ Res Public Health. 2010 February; 7(2): 675–697.
Published online 2010 February 24. doi: 10.3390/ijerph7020675.
The Changing Disease-Scape in the Third Epidemiological Transition
Kristin Harper and George Armelagos
We are, quite simply, living in an age of emerging infectious diseases.
Over the past three decades, dozens of new – mostly zoonotic – diseases have been identified. Some of these new, or re-emerging disease threats, include:
- The re-emergence and spread of H5N1 bird flu in 2003
- An H1N1 `Swine Flu’ pandemic in 2009
- Swine Variant Influenza viruses (H1N1v, H1N2v, H3N2v)
- MERS-CoV and other `bat borne’ viruses like Nipah and Hendra
- H7N9, H10N8, H5N2 and other emerging avian flu viruses
- Lyme Disease, CCHF, Heartland Virus, SFTS, and other tickborne diseases
- The global spread of MRSA, along with the recent arrival of of NDM-1 and other Carbapenemases that threaten the viability of our antibiotic arsenal.
- An explosion and spread of mosquito-borne diseases like dengue, chikungunya & malaria
- Even old scourges, once thought on the way out, are showing new signs of life . . . like Pertussis, measles, and polio.
- Perhaps most troubling of all has been the emergence of increasingly drug resistant strains of tuberculosis.
- And the one that has everyone’s attention right now; Ebola.
If you consider the toll they take each year in terms of lives lost, misery, and dollars – the most effective terrorists in this world are not humans, they are microbial.
And in a lot of places around the globe, they not only have the upper hand, they are gaining territory. .
Yet, it wasn’t until the mid-1990s that interest in these emerging pathogens really took off. The CDC only began publishing the EID Journal, a highly respected peer-reviewed journal on emerging pathogenic threats, in 1995. Today emerging disease threats, and neglected tropical diseases, are a hot topic in scores of respected journals.
Currently there is a lot of public concern over the Ebola virus, and while it is a fearsome disease, it has far less potential to wreak global havoc than many of the pathogens on the list above.
Viruses that spread via respiratory routes, like MERS-CoV, the ever expanding flock of avian flu viruses, reassortant swine flu viruses, and other respiratory pathogens are all better equipped to start a global epidemic than is Ebola.
None of which is to suggest that Ebola isn’t a serious threat, only that if it manages to spread beyond Africa, it is more likely to manifest in the form of very small, sporadic, localized outbreaks, rather than as a global epidemic.
Alas, the same can not be said for many other emerging viruses, should any of them adapt well enough to humans to transmit easily. Which is why, early this year, we looked at an assessment by the Director Of National Intelligence who includes emerging infectious diseases and Influenza Pandemic As A National Security Threat.
From that report:
Worldwide Threats Assessment – published January 29th, 2014,
Health security threats arise unpredictably from at least five sources:
- the emergence and spread of new or reemerging microbes;
- the globalization of travel and the food supply;
- the rise of drug-resistant pathogens;
- the acceleration of biological science capabilities and the risk that these capabilities might cause inadvertent or intentional release of pathogens; and
- adversaries’ acquisition, development, and use of weaponized agents.
Infectious diseases, whether naturally caused, intentionally produced, or accidentally released, are still among the foremost health security threats. A more crowded and interconnected world is increasing the opportunities for human, animal, or zoonotic diseases to emerge and spread globally. Antibiotic drug resistance is an increasing threat to global health security. Seventy percent of known bacteria have now acquired resistance to at least one antibiotic, threatening a return to the pre-antibiotic era.
This was, admittedly, just one of many threats discussed in this 27 page threat assessment. Others include cyber attacks, terrorism, extreme weather events, WMDs, food and water insecurity, and global economic concerns.
A week before that report was issued, Dr. Thomas Frieden – Director of the CDC – penned an opinion piece for CNN called How to Prevent the Next pandemic ( see CDC Director Frieden: On Preventing A Pandemic). Many of these themes are carried forward on the CDC’s Global Health Website at:
Why Global Health Security Matters
Disease Threats Can Spread Faster and More Unpredictably Than Ever Before
A disease threat anywhere can mean a threat everywhere. It is defined by
- the emergence and spread of new microbes;
- globalization of travel and trade;
- rise of drug resistance; and
- potential use of laboratories to make and release—intentionally or not—dangerous microbes.
In 2014 alone, in addition to the spread of Ebola, we’ve seen the importation of H5N1 into Canada, imported MERS-CoV cases in the United States (along with 20+ other countries), imported H7N9 to Taiwan and Hong Kong, imported CCHF in the UK, and Lassa fever in a traveler in Minneapolis, and Chikungunya has infected 500,000 people in the Caribbean over the past nine months.
And frankly, these are just the highlights.
The simple truth is, while Ebola isn’t likely to rise to the level of a global epidemic, nature’s lab is open 24/7, and it is continually producing new candidates (or refining old ones) to spark the next pandemic.
Viruses like H7N9, H5N1, and H3N2v continue to mix and match genes, looking to hit the right combination to spread easily in humans. Old influenza nemeses, to which we have limited community immunity (like H2N2) still lurk in avian populations, and upstart coronaviruses like SARS and MERS-CoV are still testing the waters, as they try to `figure us out’.
All of which means that if and when Ebola is contained (and I believe it will be), the greater threat won’t have gone away. Whether the `next pandemic threat’ comes in six weeks, six months, or six years – or from what location or source - is unknowable.
But few scientists would argue that another pandemic won’t emerge at some point.
Which is why, when the media hype and public concerns over Ebola dies down – we should not let our resolve to strengthen public health – both here, and around the globe - die with it.
We live in an age where these threats aren’t going to go away, and we can ill afford to let our guard down.
For more on pandemic preparedness, you may wish to revisit:
The Global Reach Of Infectious Disease
HSPH Video: The Next Pandemic: Are We Ready?
Pandemic Preparedness: Taking Our Cue From The Experts