Microscopic Parasite Toxoplasma Gondii Linked to Personality Changes


Microscopic parasite Toxoplasma gondii

Toxoplasmosis, an infection caused by the microscopic parasite Toxoplasma gondii, infects about 22.5% of Americans, aged 12 and older. Researchers tested participants for T. gondii and had them complete a personality questionnaire. Both men and women infected with T. gondii were more extroverted and less conscientious than non-infected participants.

The changes are thought to come from the parasite’s influence on brain chemicals. The scientists published their findings in the European Journal of Personality. Toxoplasma manipulates the behavior of its animal host by increasing the concentration of dopamine and changing the levels of certain hormones, states Jaroslav Flegr, of Charles University, Prague, in the Czech Republic.


Red arrows point to Toxoplasma gondii in a pig’s lung.

Humans carry the parasite, but its life cycle must play out in cats and rodents. Infected mice and rats lose their fear of cats, increasing the chances that they will be eaten, allowing the parasite to enter the cat and spread through its feces.

In humans, T. gondii‘s effects are subtler. The infected population has a higher rate of traffic accidents and people with schizophrenia have higher rates of infection. In a new study, a pattern seems to have appeared in infected men. The longer they were infected, the less conscientious they were. This correlation supports the scientists’ hypothesis, that the personality changes are a direct result of the parasite.

T. gondii is contracted through exposure to undercooked contaminated meat, unwashed fruits or vegetables that stem from contaminated soil, and tainted cat litter. The rates of infection in France are much higher than in the USA. The parasite is the reason why pregnant women shouldn’t clean litter boxes because the parasite can do much more damage on fetal brains than in adults.

Reference: “Higher Extraversion and Lower Conscientiousness in Humans Infected with Toxoplasma” by Jitka Lindová, Lenka Příplatová and Jaroslav Flegr, 15 July 2011, European Journal of Personality.
DOI: 10.1002/per.838

4 Comments on "Microscopic Parasite Toxoplasma Gondii Linked to Personality Changes"

  1. What is the test to see if I am infected? What can I do to rid myself of these parasites if I am?

    • I had this virus, 15 years ago. I was sick for months and saw many doctors and finally one of the doctors send me for blodd test for detection and I was positive.

  2. Tanya R Fleissner | May 17, 2020 at 10:27 am | Reply

    Yes! This is what I have, and I have been struggling for 5 months. I have been behaving so out of character for me. I have been to 3 different doctors, none of which discovered this. I refused to go on a neurological medication, and am glad I did. They had the wrong diagnosis. I am currently trying homeopathic treatments. Wormwood is suppose to help. I am 4 days in. Pray for me, please.

  3. Dr Shahid Malik | November 28, 2022 at 5:02 pm | Reply

    Most motor-bike accident victims are parasite positive . Unfortunately , even with high accident rate , their organs cannot be transplanted , due to this infection

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