The uneasy coexistence of predators and pathogens

Disease and predation are both highly important in ecology, and pathogens with multiple host species have turned out to be common. Nonetheless, the interplay between multi-host epidemics and predation has received relatively little attention. Here, we analyse a model of a predator-prey system with disease in both prey and predator populations and determine reasonable parameter values using allometric mass scaling relations. Our analysis focuses on the possibility of extinction events rather than the linear stability of the model equations, and we derive approximate relations for the parameter values at which we expect these events to occur. We find that if the predator is a specialist, epidemics frequently drive the predator species to extinction. If the predator has an additional, immune prey species, predators will usually survive. Coexistence of predator and disease is impossible in the single-prey model. We conclude that for the prey species, carrying a pathogen can be an effective weapon against predators, and that being a generalist is a major advantage for a predator in the event of an epidemic affecting the prey or both species

Framing the roots of critical COVID-19 public health concepts:Intersecting history and epidemiology

In order to contain the COVID-19 pandemic, we relied on age-old mitigation strategies such as isolation and quarantine, hygiene and sanitation, and vaccination. These strategies are rooted in experiences from past pandemics that have shaped our understanding of infectious disease control. This chapter reviews the historical origins of these pillars of mitigation and uses insights from modern epidemiology to reflect on how COVID-19 affects our view on these strategies in the future. Quarantine originated during the Black Death in the 14th century and was enforced during the 18th-century plague outbreaks. Cholera influenced the hygiene movement across Europe and accelerated developments in sewage systems and access to clean drinking water. The concept of vaccination started with the late 18th-century discovery by Edward Jenner of the immunising properties of cowpox against smallpox. Jenner’s vaccine was the start of vaccination programmes and eventually led to the eradication of smallpox globally in 1979. During the COVID-19 pandemic, quarantine, isolation, and a focus on hygiene measures helped us to overcome the initial pandemic phase until vaccinations became available. The next pandemic looms on the horizon and experiences from past pandemics will be crucial in preparing for and overcoming the new crisis.</p