Parasitism with Andrea Pitio

Parasitism is classically understood as a one-sided, exploitative relationship where one being benefits at another’s expense. Cowbirds, deer ticks, liver flukes; parasitic flatworms who take over the brains of snails, fungi who invade ants’, barnacles who attach to crabs’ genitals; ticks, mosquitoes, toxoplasmosis from cat poop; there are at least hundreds of thousands of parasites for vertebrates alone, and therefore many millions of species who parasitize across all phyla.

Parasitism, especially defined as unequal exploitation, extends well beyond biological physiology as well. Corporations exploit the labor of their workers, empires endlessly steal their land base, and billionaires and their hedge fund managers take everything they can from the world’s people and their governments.

We tend to assume parasites are just plain bad. How could they be anything but, when they take at their hosts’ expense? But as science delves into more of the complexity and interrelationship within Earth’s systems and interspecies relations, parasites are increasingly recognized as not-so-simply-parasitic. For instance, according to a wide study, parasites can regulate host immune system function, help regulate the host microbiome, and decrease the prevalence and severity of autoimmune diseases within the host. As the researchers from that study wrote, “The boundary between mutualism, symbiosis, and pathological parasitism is narrow and is frequently overlapping without a theory to clearly explain this relationship between the parasite, host, and ecological niche.”

To what extent, then, do parasites exist? Despite its ecological origins, is the term more useful sociologically than it is biologically? What is revealed in our search — or empathy — for parasites?