As the population continues to rise, so too does the war on disease.  For the last few thousand years, humans have fought a multitude of diseases- zoonotic, organic, and man-produced.  Over the course of history, these diseases have changed in their nature to match the societal and cultural changes taking place in the world- including rapid population growth and various lifestyle changes that result in the adaptation of disease to take root in populations and cause massive devastation.  The result of history leaves modern scientists with highly-adapted, intelligent, complex diseases that are vastly different from the organisms our ancestors once suffered from.

Many years ago, when hunters and gatherers roamed the earth, sources of illness were rare and isolated to worms, fleas, lice, and the occasional infectious disease caused by an animal.  These infections rarely infected entire groups or tribes of humans until a drastic rise in population of over one hundred and sixty times began in 8000 BCE and ended in 1750 CE.  Since the population growth began, the positive correlation between population and disease rate was also confirmed.  Lifestyles changed from hunter-gathering tribes to densely-populated communities that led increasingly-sedentary lives.  Previous ancestors that had constantly moved about the land were now settling in communities and domesticating animals.  They did not know about hygiene or about the disease vectors that bred on domesticated animals.  Water stored in vessels were breeding grounds for more vectors such as mosquitoes.  Animals and humans shared a common water source and their waste stayed close to the community, infecting the water and nearby food sources.  These kinds of changes not only resulted in smaller outbreaks of disease, but also resulted in epidemics and pandemics such as the Justinian Plague of 541-544 CE.  This was the first large pandemic of the bubonic plague.  The plague started in Ethiopia and quickly spread to Egypt by 540.  By 541, it had traveled trade ships to Constantinople (Frith).  This plague spread quickly because of the dramatic change in society that began 11,000 years ago.  The close communities and lack of hygiene or education regarding diseases allowed it to spread quickly, and trade carried vectors far away from the original site.  The changes in society and culture did not end long ago, rather, infectious diseases have found ways to adapt to the ever-growing challenges confronted by modern science and technologies.

Changes in society and culture today have brought about many advancements in the form of medicine, vaccines, hygiene standards, and sanitary waste practice, along with many others.  Science and technologies have resulted in the large reduction of many diseases, as well as the eradication of smallpox.  However, new challenges such as globalization, climate change, and politics threaten the rise of disease rates again.  The rise in population also leads to environmental changes that can result in greater disease rates, such as the fertile soil exhaustion seen in various agricultural countries, freshwater depletion, and the loss of some animal and plant food species.  Due to a decrease in resources, rising food prices become more common, resulting in the impoverished relying on cheaper food to sustain them, or the lack of food at all.  A lack of healthy food and safe drinking water greatly reduces the health of the poor, leading to rising disease rates within the poor.  Additionally, climate change causes a decrease in jobs because of events such as the acidification and deoxygenation of saltwater, the destruction of coral reefs, and overfishing, which reduces the availability of seafood protein.  A decrease in jobs brings the correlation of increased poverty rates and allows diseases to spread more easily.  Diseases such as zika, dengue, and chikungunya are spreading more easily, especially within African countries, and there is an accelerated emergence of new infectious diseases that is coupled with an increased resistance to microbial agents (McMichael)(Haines & Ebi).  Climate change also brings changes in weather patterns, which help spread disease and changes migratory birds’ movement patterns- which allows the vectors to spread disease to new countries and in different seasons (McMichael).

Although the presence of new medicines and technologies offers hope to control the spread of infectious diseases, the effects of environmental changes and human interventions runs a deep cut in the progress made.  Effects such as climate change spreading disease more rampantly, poverty, and the scarcity of clean and reliable food sources increases the complexity of infectious diseases and gives new challenges to modern scientists and citizens.  By studying the past and looking forward to the future, we can come to a better understanding of how to address these problems and create new solutions to a rapidly-changing world.

 

 

References:

Frith, John. “The History of Plague – Part 1. The Three Great Pandemics.” The Journal of Military and Veterans’ Health 20, no. 2 (2012)

Haines, Andy & Ebi, Kristie. “The Imperative for Climate Action to Protect Health.” The New England Journal of Medicine 380, no. 3 (2019): 263-273

McMichael, Anthony J. “Globalization, Climate Change, and Human Health.” The New England Journal of Medicine 368, no. 14 (2013): 1335-1343