When our ancestors descended from the trees they opened themselves up to a whole new world of diseases, from tick and flea borne to contaminated water sources. One of our ancestors H. habilis seems to show some of the earliest zoonotic infections, they likely acquired them from some of the aforementioned pests and could have caught things like trichinosis from their butchered meat. Disease really started to explode when H. sapiens shifted away from their lives as hunter-gatherers and the agricultural revolution began. This revolution resulted in an explosion in the human population which meant more opportunities for disease to take root. As animal domestication became commonplace the rate of disease in the populations seemed to jump and we now know the number of diseases these animals can hold.
One of the earliest plagues in history was the Pharaohs’ Plague, it was discovered to be the blood fluke Schistosoma and in Ancient Egypt, it was possibly considered a sign of puberty in men. Schistosomiasis took hold as villages grew along the Nile, as they grew together they became towns and then cities. The Egyptian farmers used the Nile to irrigate their fields when the banks of the Nile would flood the water would wash the disease-ridden snails into the fields, as the farmers would walk among their crop the larvae would penetrate them and make them sick. The Plague of Justinian was likely the bubonic plague, as Rome expanded its borders the men fighting for the empire were exposed to novel diseases and the plague began ravaging the populace. It decimated the armies and then it left the Roman Empire vulnerable to the Muslim armies that invaded and the empire began to fall with the plague one of greatest antagonists.
One of the greatest challenges in epidemiology today is the interconnectedness of the world. Within a day of leaving America you can be in Europe and traveling from country to country, this greatly increases the ability of the pathogen to reach new victims. The SARS virus struck fear into the heart of many people in the early 2000’s. Part of the fear stemmed from the fact that it came from a relatively well connected country and in less than a year 26 countries had confirmed cases. There is such a desire in a lot of young people to explore the world and see new places. Doing so though comes with some inherent risk of being exposed to new disease.
With the advent of air travel diseases now have the ability to explode in scope relatively quickly. Currently with the issues in global warming we also have diseases that haven’t been seen in thousands of years getting released from the permafrost. A final issue is the growing resistance to antibiotics in bacterial pathogens, as a scientific community it is our duty to come up with new ideas to fight of these diseases and help humanity.