The Impact of Climate Change on Disease

By Guest Blogger Richard A. Lutes, MD, President / CEO of Angam Scientific, LLC

Humans have forever been locked in an evolutionary arms race with pathogens.  The success or failure of a pathogen is entirely dependent on its ability to survive, reproduce, and spread to a new host or environment. The host will attempt to recognize and subsequently rid the body of the intruder. Co-evolution between host and pathogen naturally occurs because of these interactions and it is a battle that will continue into the foreseeable future. At the basic level, this concept suggests that when a host evolves new defenses to thwart a pathogen’s attack, the pathogen is forced to adapt a more impressive attack strategy to penetrate the heightened defenses. In response, the host must once again develop new defenses to cope with the new attack mechanism, and the cycle continues.

Macro of mosquito sucking blood

One factor that has frequently upset the scales in favor of the pathogens is the environment.  There are numerous examples of the environment factors coming together to create global pandemics such as the plague, small pox, HIV and influenza in 1918.  These events were responsible for millions of lives lost.  The greatest threat today is from climate change.  Climate change is under way and proceeding more rapidly than anyone previously expected and we are now seeing on a global scale the effects on human health.

Warmer winters are allowing ticks to mover further north carrying diseases such as Lyme Disease, Powassan virus, Bourbon viruses and others with lethal consequences.  One of the clearest signs of health risks in a warming world has emerged in one of the world’s most advanced economies, as Canada belatedly struggles to cope with Lyme disease’s migration in North America.  In the United States, reported cases of Lyme disease have increased from fewer than 10,000 reported cases in 1991 to more than 27,000 cases by 2013. Canada was well-positioned to be affected by the spread of the disease. Warmer temperatures are allowing Lyme-carrying ticks to thrive further north.  As early as 2005 modeling, published by researcher Nicholas Ogden, then at the University of Montreal, indicated that the geographic range of the Lyme-carrying tick could expand northward significantly due to climate change in this century.  It is not just Canada that is threatened but there are a growing numbers of disease-carrying ticks “moving North” to France, Britain and as far as Scotland and even Russia

Where will the next global threat come from? With the planet warming tropical countries are the most bio-diverse areas on the planet and are a likely source of the next pandemic.

map threats disease

South America is a hotbed of potential killer viruses, new research from the EcoHealth Alliance in New York has revealed.  Their study is the first comprehensive look at all viruses known to infect mammals and the findings show bats are the biggest threat, carrying a “significantly higher proportion of viruses able to infect people than any other group of mammals”.

The most recent example of diseases originating in South America is the Zika virus outbreak which started in Brazil.  Although almost all US cases today are from travel to the US, global warming may make southern US a potential source of infection.

It is not just in tropical countries where climate change may pose a threat.  In Antarctica and the North Pole climate change is melting the permafrost.

In the cold dark permafrost, with no oxygen, pathogens can survive in soils frozen for millions of years and when thawed may release ancient viruses and bacteria.  Scientists have managed to revive an 8 million-year-old bacterium that had been lying dormant in ice, beneath the surface of a glacier in the Beacon and Mullins valleys of Antarctica. In the same study, bacteria were also revived from ice that was over 100,000 years old.  These pathogens can spring back to life as they thaw.  Pathogenic viruses that can infect humans or animals might be preserved in old permafrost layers, including some that have caused global epidemics in the past.  A most recent example occurred in 2016 when multiple anthrax cases were reported in Siberia due to permafrost thaw.

Global Warming

If the world proceeds on a “business as usual” path, atmospheric CO2 concentrations will likely be more than 700 ppm by 2100, and they will still be rising. This is nearly double the current level and much more than double the preindustrial level of 280 ppm. State-of-the-art climate models suggest that this will result in an increase of about 3.5oF in global temperatures over the next century. This would be a rate of climate change not seen on the planet for at least the last 10,000 years.

In this hotter planet, we will see new diseases frequently which will require constant surveillance to identify and treat the new emerging diseases.

Dr. Lutes recently participated in a UN event co-organized by GFDD, the United Nations Association of the United States of America Council of Organizations (UNA USA COO) and the Institute for Life Sciences Collaboration. The event, an International Conference on Novel Diagnostics & Affordable Treatment, was titled Advancing UN Sustainable Development Goal 3 (Good Health & Well-being) and took place at the UN Church Center. It was a unique opportunity for attendees to engage with a diverse panel of speakers that included high-level representatives from the World Health Organization, the World Bank and several medical practitioners. The conference, which took place before an audience of 80 people, was split into three parts including two panel discussions on Diagnostic Challenges of Resurging Diseases and Applicable Affordable Treatments and a networking session. The panelists discussed a wide range of ongoing public health issues in developing countries, from tropical virus outbreaks and their interrelation with climate change, to the prevalence of pandemics such as tuberculosis or rabies, offering effective yet affordable solutions to help tackle them.

To find out more about the outcomes of this event, please click here

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