Toxoplasma infection and behavioral change in human

Cats are so lovely that many people are fond of touch them. But you should be cautious when making fun with a cat outside.

Toxoplasma gondii is one of the parasites which has a unique character. It can reproduce only in the cat family, so cats are the final host of it. However, it can survive in various environments in warm-blood animals. And surprisingly, approximately one-third of all human is considered to have toxoplasma.

Toxoplasma infection is usually almost harmless. When you are infected, you hardly notice it, or common cold like symptoms continue for some weeks. However, compromised hosts such as in AIDS may sustain a fatal damage. Also, if a pregnant woman is infected, toxoplasma may inflict several abnormality to the infant.

Toxoplasma is transmitted via cats stool. You should wash vegetables carefully before eating them. Raw meats can also be contaminated.

Interestingly, there are some reports in which the influence of toxoplasma on the host's character is suggested. Rats with toxoplasma are said not to feel fearful to cats. They tend to be caught by a cat. Toxoplasma can move from the rat to the cat which bit the rat. Therefore, the character change of the rat can be interpreted that toxoplasma would control the rat' behavior so that it can move to the cat as the final host.

In human, there are a few studies similar to the rat. Infected men are likely to be antisocial, and infected women will be attractive.

Recently, a cross-sectional study was conducted to examine the possibility that toxoplasma makes human impulsive. In this study, patients with Intermittent Explosive Disorder (IED) was investigated, compared to healthy people and patients with other mental disorders. As a result, patients with IED were more likely to have toxoplasma than other participants.

Clinical Journal of Psychiatry: Toxoplasma gondii Infection: Relationship With Aggression in Psychiatric Subjects

This study was cross-sectional, so it has not been proven that toxoplasma causes impulsiveness on a human. It is possible that inherently impulsive persons may try raw food, leading to the infection of toxoplasma. To prove the effect of toxoplasma infection on the personality change, a longitudinal study should be performed in which several people were examined twice for some years. If behavior changes are observed after toxoplasma infection in many people, this hypothesis will be certain.

Parasites are sometimes a theme of literature, especially in Sci-Fi. However, there are few things clarified about them. Many parasites have a risk of invading the human brain. And, it is not sure what will happen when it occurs.