Parasites: Their Impact on Human Health & Behavior with Kathleen McAuliffe

Parasites are more common than you would imagine.  In this episode of HealthMade Radio Dr. Michael Karlfeldt discusses parasites, parasitic manipulation, and how to avoid being ‘controlled’ by maintaining diverse gut flora.  Kathleen McAuliffe’s recent book, “This Is Your Brain On Parasites,” describes some of the many ways these creatures manipulate their hosts’ behavior to ensure their survival and successful reproduction. Parasites can have a direct impact on our immune response and our susceptibility to illness and disease. 
Listen to this insightful interview to learn more about:

  • Gut microbe and pathogenic dominance
  • Leaky Gut: How microbes impact our inflammation
  • How the shifts in modern society have decreased microbiome diversity thereby decreasing immune response and increasing disease prevalence
  • The source of parasites, our pet and our foods such as meat and seafood
  • Pathogenic manipulation in human behavior

Sterile environment, antibiotics, exercise, and decrease in fiber decrease diversity in the gut which is associated with an increase in disease and infection. Kathleen McAuliffe 

The discussion begins with the impact of parasites on animals. Rats being manipulated to be attracted to cats.  The rodent afflicted with this parasite, called toxoplasma, soon finds itself in the belly of a cat, which, conveniently, is the only place the parasite can sexually reproduce.

Humans aren’t immune from manipulation by parasites. A malarial parasite can cause subtle changes within the human body in order to perpetuate its dangerous mission.

“When it infects a person, it introduces an anticoagulant — sort of like a blood thinner. So when other insects feed on that person, they can suck more infected blood out of them,” McAuliffe says. “And then these little flying syringes go around and infect many more people.”

The parasite can also change the odor of its human host; it may even amplify our scent. That means more insects, including not-yet-infected ones, will be attracted to the body of an infected person. They will feed on this person and then spread the parasite to more people.

Their cleverness doesn’t end there: A study in Kenya found that insects with the parasite have a stronger preference for people whose malaria is at a transmissible stage and less of an attraction to people whose malarial infection is not yet transmissible.

Evidence suggests that toxoplasma, the parasite that alters a rat’s behavior, can change human behavior, too. Humans typically get this bacteria from cats. After it gets into a cat’s gut, the cat begins shedding the parasite’s eggs in its feces. People can accidentally be exposed to it when changing a cat litter box. Exposure can also sometimes happen while gardening or by not thoroughly cleaning garden vegetables.

“Twenty percent of Americans have the parasite in their brain, and a lot of research suggests that, in a small percentage of people, it can contribute to mental illnesses such as schizophrenia and bipolar disorder,” McAuliffe says. 

More About Kathleen McAuliffe

Kathleen McAuliffe is the author most recently of the book This Is Your Brain On Parasites: How Tiny Creatures Manipulate Our Behavior and Shape Society (Houghton Mifflin), a bestseller in parasitology and microbiology that has been translated into six languages. Over the decades, she has written articles—many featured on covers—for over a dozen national magazines, including Discover, The New York Times (both the Sunday Magazine and newspaper), The Atlantic, US News & World Report, Smithsonian, and the Los Angeles Times. Earlier in her career, she was a health columnist for More Magazine, and a senior science editor at US News & World Report and Omni Magazine. 

 In addition to writing, McAuliffe is an adjunct professor at the University of Miami where she is currently teaching a course on the human microbiome.

McAuliffe was educated at Trinity College Dublin, Ireland, obtaining an M.A. in natural science after graduating with first-class honors (highest distinction). Her final year thesis on electroencephalography (EEG) recordings of the human brain was presented at the Eastern Psychology Association Conference in 1977.

McAuliffe resides in Miami, Florida with her husband, a physicist at the University of Miami.

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