The human body is home to teeming billions of organisms that affect our everyday lives, and this "microbiome" may very well influence every aspect of our health and disease, from strengthening our immune system, to causing debilitating diseases and may even determine whether we will become obese or not. An integral part of this unseen biosphere are the vast numbers of parasitic organisms that call our bodies home. According to some estimates, parasites outnumber free-living species four to one, prompting Yale lecturer and New York Times columnist Carl Zimmer to comment that, "...the study of life is, for the most part, parasitology."
To illuminate some of the mysteries around human-pathogen interactions, my institution, the University of California, Irvine, recently created a free MOOC (a Massive Open Online Course, meaning anyone with an Internet connection can enroll) on the Canvas Network to teach the world about parasitology and other scientific topics through the lens of vampires (yes, you read that right). Specifically, we've partnered with FX Networks to leverage the popular TV series The Strain as a way to help people understand the nature of parasites.
For the uninitiated, The Strain is based on a novel of the same name by Guillermo Del Toro and Chuck Hogan, and its premise takes a modern and scientific twist on the vampire legend. An aggressive parasite infects New York City, turning people into vampires. These aren't the supernatural vampires depicted by Bram Stoker, or the sparkly ones from Twilight, but instead are fangless humans whose biology has been altered, most notably through the development of a long, retractable, tongue-like proboscis that the creatures use to infect new victims and spread the pathogen.
While fantastical, The Strain provides a useful storyline for explaining how parasites work, and it makes the academic experience more interesting for students through a pop culture touchpoint. Our course aims to teach the general public about some of the more practical applications of parasitology, including a better understanding of how the human body interacts with parasitic pathogens.
Most parasites live inside the body for years without producing any noticeable symptoms, but they do have the potential to change human behavior in dramatic ways. For example, a single-celled organism known as Toxoplasma may currently reside within one-third of all humanity. Typically, this parasite produces only mild flu-like symptoms, but in rare cases it has been linked to changes in mood (increased tendencies to disregard rules, for example) and even more dramatic conditions like impaired motor skills, and even schizophrenia.
The Toxoplasma strain has an even stranger impact on rats, according to Stanford research. The cat's stomach is an ideal reproductive environment for Toxoplasma; the parasite infects rats and infiltrates their brains, creating a neural link between cat's urine and the rats' reproductive desire. In an ironic and sinister twist of nature, this compels the rat to lose its fear of the cat as a predator and, potentially, instead seek it out in anticipation of romance. When the rat is consumed, the parasite can reproduce from inside the cat's digestive system.
The parasite in The Strain is more sinister and sophisticated, fundamentally changing its host's body and mentality. Like the Toxoplasma, it persuades the host to seek out uninfected humans -- with a preference for the host's loved ones -- and spread the disease. It also makes the host complicit with the commands of the species' alpha and seminal figure, an ancient creature known as "The Master." The parasite also compels the growing vampire horde to congregate and nest in the abandoned subway tunnels under New York City.
While these kinds of biological and behavioral modifications are extreme and have an element of science fiction to them, they are rooted in real science and offer tremendous value in making the academics of parasite biology come alive in an educational setting. As a scientist and educator, I am always looking for new ways to convey the complexities of science in a way that resonates; invoking pop culture, where appropriate, has shown promise as a kind of Digital Age literature review. And it turns out, TV vampires provide a pretty powerful case study in understanding parasitology.