First Advisor

Luis Ruedas

Date of Award

Summer 5-2023

Document Type


Degree Name

Bachelor of Science (B.S.) in Biology and University Honors






Virus, Biology. DIsease. Human, Dilution Theory, Correlation




Viral diseases and their prevalence--including both the number of cases and the appearance of new viruses--has increased in the last century, and these diseases have become an increasing threat to human health and well-being. The influenza and COVID-19 pandemics served both as introductions and reminders respectively to the power these viruses have to destroy and disrupt human life. As such, it intimates a necessity to investigate possible causes for the increase in these deadly diseases. Among these plausible causes is the dilution effect hypothesis, which states that decreasing the biodiversity of an ecosystem increases a pathogen's ability to infect, both through direct and cross-species transmission. This, in combination with the devastating deforestation/habitat loss caused by humans in the last century, led to the idea that humans may be partially or even largely responsible for this increase in viral prevalence. Discussion with a professional in zoonotic disease studies in turn led to the analysis of this possible relationship and what research question and format of study would prove best to explore this further. The research question and basis of the paper is: is there reasonable evidence to plausibly conclude that disruption of ecosystems by humans is the cause for the perceived increase in viral disease prevalence in humans? To explore this question further, a literature review was undertaken and statistical analysis performed on four primary variables: human population increase, viral prevalence (number of cases), viral appearance (new recorded viruses), and loss of forest cover over time and per decade. By exploring these variables and using statistical analysis it could then be explored whether there was a reasonable correlation among the variables, indicating whether or not the hypothesis that human ecosystem disruption could be the cause for increased disease prevalence is supported by reasonable evidence, as well as and the possible implications of this result.

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