A parasite that infects the human brain, subtly changing its personality and social behavior, and capable of passing from mother to infect an infant in utero? That is the essence of a body horror, but this little rascal isn’t fiction. And it gets better: this parasite is considered to be one of the most successful parasites in the world due to its widespread, global distribution as well as its capacity to infect nearly every type of body tissue in all warm-blooded vertebrates (a). Schedule a phone conference with Spielberg and Cruise ASAP, guys, we’ve got the next sci-fi-action blockbuster on our hands (brains?). We’re looking at the ubiquitous protozoa Toxoplasma gondii and research on its capacity to modulate human personality and behavior.
T. gondii is an obligate intracellular parasite that has a vast host distribution, capable of infecting all species of mammals. Domestic cats and other felines are, however, the definitive host for the parasite’s reproductive stage. As such, all other animals serve as intermediate hosts of this polyxenous parasite. Humans are usually infected through consumption of infected raw or undercooked meats that happen to be studded with tissue cysts, typically lamb or pork (a). Turns out that T. gondii infection, known as “toxoplasmosis”, is the most common food-borne parasitic infection that requires hospitalization, and the third most common food-borne illness overall (b). Indeed, a study in 2002 conducted in the United Kingdom examined commercial meat sold in grocery stores and found that 38% of samples were infected with T. gondii cysts (h).
