Bill Sullivan Ph.D.

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Can “Tiger King” Madness Be Explained by a "Cat" Parasite?

Could a parasite we get from cats explain the bizarre antics in “Tiger King?"

Posted Apr 02, 2020

The following article contains minor spoilers for the Netflix docuseries "Tiger King: Murder, Mayhem and Madness."

“Tiger King: Murder, Mayhem and Madness” is a docuseries on Netflix that is taking the world by storm. The story lifts the veil on the surprisingly nefarious world of collecting and exhibiting big cats, such as tigers and lions.

But it’s not only the adorable cubs or awe-inspiring power of the adult cats that make people tune into the show; it’s the bizarre behavior of nearly everyone involved in this enterprise. What could it be about the big cat business that seems to attract or produce such peculiar characters?

The answer may lie in the cats themselves, or more precisely, their feces. All cat species support the sexual stage of a single-celled parasite called Toxoplasma gondii. Consequently, cats excrete billions of infectious oocysts into the environment when they acquire Toxoplasma. Other animals, including people, can then become infected with the parasite after they inhale or accidentally ingest these oocysts.

When people become infected, the parasite quietly disseminates to various organs, including the brain. The immune system quickly controls parasite growth and puts the infection into a dormant stage; most people never even experience symptoms of acute illness. But emerging studies suggest that harboring these dormant parasites in the brain is not benign.

As outlined below, a plethora of studies have correlated the presence of Toxoplasma in the brain (toxoplasmosis) with a variety of neurological issues and behavioral anomalies. Given that many of the individuals featured in “Tiger King” have worked so closely with cats for so long, one might wonder if Toxoplasma could be responsible for their unusual behavior.

Consider the man at the center of the story: Joseph Schreibvoge, aka Joe Exotic. Joe is an eccentric person who has taken lots of risks in his life and appears to experience impulsive explosive disorder (rage disorder). In 2018, Joe was sentenced to 22 years in prison for participating in a murder-for-hire scheme to kill his primary adversary, Carole Baskin. 

Many of the behaviors that got Joe into trouble turn up in psychiatric surveys of human toxoplasmosis. Multiple studies have linked Toxoplasma infection to increased risk-taking behavior. A 2016 study led by Emil Coccaro at the University of Chicago reported that people with rage disorder are twice as likely to have latent toxoplasmosis.

But are people infected with Toxoplasma more likely to end up incarcerated? One study from 2014 found that inmates in a Durango City jail were more likely to have toxoplasmosis than the general population in the same city.

Kelci Saffery was an employee at Joe Exotic's GW Zoo who lost his lower left arm after an accident with a caged tiger. In Saffery’s words, "I broke protocol and stuck my hand in a cat cage instead of using the stick provided. The cat let go and pushed my arm back through the cage." A 2012 study found that people who had workplace accidents were more likely to be infected with Toxoplasma than controls.

“Tiger King” revealed that numerous people at the GW Zoo had issues with drugs and alcohol. One of the more memorable stories was that of John Finlay, one of Joe’s husbands. A 2018 study found that toxoplasmosis was significantly higher among substance abusers irrespective of the type of drug used. Similar findings have been reported for toxoplasmosis and alcohol abuse.

Bhagava “Doc” Antle is another beguiling character in the “Tiger King” story, portrayed as having a polygamous way of life with multiple female companions. Joe Exotic led a similar polygamous lifestyle. Could sexual behavior be influenced by Toxoplasma infection as well? Several studies have shown that toxoplasmosis increases testosterone, and increased testosterone is associated with having multiple partners.

Several individuals in “Tiger King” are astute business people, including Jeff Lowe, Carole Baskin, and Joe Exotic. Remarkably, a 2018 study conducted by Pieter Johnson at the University of Colorado has linked Toxoplasma infection with increased entrepreneurial behavior. Their study found that, among professionals attending entrepreneurship events, those with toxoplasmosis were nearly twice as likely to have started their own business compared with other attendees.

Speaking of Carole Baskin, what about the accusation that she was behind the disappearance of her first husband, Don Lewis? It should be emphasized that there is no evidence linking her to a crime, but there is evidence that Toxoplasma is linked to hostile and violent behavior. A 2014 study concluded that Toxoplasma infection increases aggression in women and infected women were more likely to be murderers.

How could one parasite be responsible for so many different types of behavior? One explanation could be that Toxoplasma alters the brain in such a way that it leads to loss of impulse control and greater risk-taking. These fundamental changes in personality could manifest in varied ways, from heightened aggression to greater entrepreneurship to increased odds of being in an accident.

How the dormant parasites might affect the brain is poorly understood. Studies from my laboratory at the Indiana University School of Medicine, which have been confirmed by others, suggest that the dormant parasites cause neuroinflammation (an immune reaction in the brain) in mouse models. We have also shown that drugs reducing neuroinflammation can reverse the behavioral changes seen in mice harboring Toxoplasma.

Considered together, these observations would appear to make a compelling case that a parasitic infection that people can get from cats could contribute to strange behaviors or neuropsychoses.

However enticing this idea may be, it has substantial caveats, not the least of which is that many cat owners show no bizarre behavior. In addition, some researchers have failed to detect connections between toxoplasmosis and human behavior: a 2016 study led by Avshalom Caspi found little evidence that toxoplasmosis was related to increased risk of psychiatric disorder, poor impulse control, personality aberrations, or neurocognitive impairment.

It is also important to note that there is no evidence that any of the people in “Tiger King” are infected with Toxoplasma. Moreover, all of the studies mentioned correlate the presence of the parasite with a certain behavior—they do not prove that Toxoplasma is the cause of the said behavior. Human behavior arises from a complex interplay between genes and environment; Toxoplasma may represent a risk factor that predisposes someone towards a certain behavior, but it is unlikely to be the only factor involved. 

While it is tantalizing to speculate that a parasite transmitted by cats may infect and produce abnormal behavior in its human host, it is just as likely that the underworld of exotic animals attracts people who already have unusual attributes.