I came across this brain-teaser in David Quammen’s masterful book Spillover: Animal Infections and the Next Human Pandemic.
In general terms, we’re pretty comfortable with what a disease is. And we certainly know the difference between an attack by bacteria versus that of a lion, say. But not so fast. Here’s Mr. Quammen’s take:
Infectious disease is all around us…. It’s one of the basic processes that ecologists study…. Predators are relatively large beasts that eat their prey from the outside. Pathogens (disease-causing agents, such as viruses) are relatively small beasts that eat their prey from within. Although infectious disease can seem gristly and dreadful, under ordinary conditions it’s as natural as what lions do to wildebeests and zebras, or what owls do to mice.
So are a pack of wolves – or human cannibals – the functional equivalent of a bunch of pneumonia bugs?
Perhaps after dinner and over a glass of wine we could discuss it. Oh wait … how would we characterize what we just did to that side of beef?