Global Climate Change and Implications for Disease Emergence

Slenning (2010) examines current research and theories on the relationship between global climate change (GCC) and an increase in human and animal diseases.  He compared research from 38 different studies and decided that the biological response to GCC will be an altered balance between disease agents, vectors, and hosts to increase disease incidence.  Weather will become more variable and extreme which will destabilize ecosystems, forcing plants and animals to migrate to less habitable environments.  GCC is leading towards ecological tipping points, which, in the past, have taken millennia to recover from.  Increased temperatures are causing some synergies to become stronger and therefore spread invasive species and diseases across the globe.— Leah Kahn
Slenning, B. D., 2010.  Global Climate Change and Implications for Disease Emergence. Veterinary Pathology 47, 28–33.

            The public has struggled to understand climate change; not its definition but the sense of urgency required to respond to it.  It is difficult to grasp the gravity of the issue when there are few examples of what will result from climate change.  People want proof but many are not as of yet convinced because of the lack of physical evidence they can see.  Barrett D. Slenning studied the facts versus the theories of climate change and discovered what information is still needed to prove those theories and thoroughly convince the public.
            Vector-borne diseases are his main concern.  A vector-borne disease is a three-step process.  The disease starts as a pathogen and is picked up from a mammal by an arthropod, usually a tick or mosquito, and then is transferred to a human host through blood.  For example, ticks carry lyme disease because they feed on field mice.  It is often believed that ticks are just natural carries of the disease but they actually get it from another source.  As larger animals become less common due to deforestation, ticks more often feed on mice so the rate of lyme disease has increased.
            There are 35 years of solid proof of climate change.  The earth’s land mass has already experienced between .2 and 1 ºC increase in temperature which is basically the difference between two geological eras.  To make matters worse, Arctic temperatures have increased at twice the global rate.  Herbicides are less effective on invasive species thriving on CO2, so crops are less successful. 
            Ecosystems are changing so our relationships to them must change.  Health events like African Rift Valley fever outbreaks are driven by weather over the Indian Ocean several months before.  Warmer waters allow vectors like bluetongue and hantavirus to survive in Europe, which harms fish and human populations.  Water-borne disease flourish in the heavy rainfall certain regions like Pakistan are experiencing.  The effects of GCC are unequally distributed across the globe.
            Where the public grows frustrated is the lack of knowledge of how each disease is going to respond.  Due to extensive research, scientists have a strong idea of the several different ways diseases will react but cannot predict the precise outcome of each pathogen.  As cycles are altered, some pathogens may not survive but others will spread like wildfire.  There must be quick research done of domesticated and wildlife animals to better understand the impact of diseases.  The type of research being done must change.  Research must be performed on models that offer assumptions that can scale or transfer to other regions so conclusions can be more widely applied.

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