I have read many shocking news throughout my life, but few like the one I read the other day in the magazine National Geographic The article referred to a parasite called “Toxoplasma Gondii”, which causes Toxoplasmosis.
An evolutionary biologist of Czech origin, Jaroslav Flegr, has done a lot of research to learn more about how this protozoan affects humans. This researcher has concluded that Toxoplasma gondii can control our brains, increase suicide rates and cause mental disorders such as schizophrenia or bipolar disorder.
Toxoplasma gondii: the intelligent parasite
The cause of toxoplasmosis is one of the most interesting parasites on the planet, and it can affect all warm-blooded animals, including humans. Additionally, birds and insects (flies, cockroaches) can carry the parasite and spread it widely. Cats are the only animals where the parasite produces eggs, which is why they are known as definitive hosts; In the rest of the animals they are called intermediate hosts because the parasite does not produce eggs.
Cats often become infected when they eat undercooked and infected meat, for example, prey hunted in the wild In order for the parasite to continue its life cycle and become an adult parasite, it must lodge in the intestine of felines. Therefore, the way to achieve this is to be ingested. And how does he achieve this? Studies suggest that the parasite has evolved in such a way that it is capable of “hacking” neuronal circuits to change the behavior of rodents with such precision that they lose their fear of cats (and even become excited by their smell). so that they are easy prey for cats. We all know that mice and rats are cats’ favorite prey.
Toxoplasmosis in humans
Now, and in humans…what exactly happens? Blood tests show that toxoplasmosis, in 40% and 60% of cases, the parasite has entered the body of these people and produces the formation of antibodies. But how do people get infected? Well in different ways:
However, very few individuals present symptoms of the disease , because with a normal immune system anyone can counteract the parasite or simply present feverish symptoms or swollen glands. Although experts say that the major problem occurs during pregnancy. The greatest risk arises when the infection is contracted during the first months of pregnancy, causing abortions and fetal malformations.
Toxoplasmosis causes behavioral changes in humans
Although it seems that the parasite does not cause visible symptoms in most cases, there is research that does not confirm the same. As already mentioned, one of the first scientists who became interested in toxoplasmosis and its effects on humans was Jaroslav Flegr, and he found that The behavioral changes caused by toxoplasmosis in rodents, such as changes in reaction times, lethargy, or decreased fear, also appear in infected humans
In addition, Swedish scientists recently discovered that to travel throughout the body and reach the brain, toxoplasma gondii hijacks the same cells that are responsible for expelling foreign bodies, white blood cells. Apparently, white blood cells produce a neurotransmitter that is responsible for reducing fear and anxiety in both rodents and humans.
Flegr himself, in addition, after analyzing the database of different hospital centers, discovered that an infected individual is more than twice as likely to suffer a car accident. According to Flegr, this has to do with reducing reaction time.
The relationship between toxoplasmosis and mental disorders
In 2003, Fuller Torrey, a researcher at the Stanley Medical Research Institute in Bethesda (United States), observed a relationship between schizophrenia and toxoplasma gondii Specifically, women with high levels of the parasite were more likely to give birth to babies who could develop schizophrenia.
The hypothesis suggests that, while for most people who are infected, toxoplasma has minor effects, for others, the changes are much more exaggerated. This idea has gained strength with subsequent studies, as other work has found that antipsychotics worked just as well as other medications used to treat this pathology, thus stating that There is a relationship between psychological disorders and toxoplasma gondii infection
One of the causes of the relationship between toxoplasmosis and schizophrenia has been explained by a group of scientists in the United Kingdom, who in 2009 found that the parasite has two genes for the manufacture of L-DOPA, the precursor molecule of dopamine. . High levels of this neurotransmitter are associated with schizophrenia
Another study by American scientists found that, among 7,440 mental health patients, there was a significant relationship between toxoplasma infection and a type of bipolar disorder in which patients suffer more predominantly depressive symptoms.
Toxoplasmosis and suicide
Studies on the relationship between toxoplasmosis and psychological problems have continued and have provided surprising results. A study published in 2009 by the Journal of Nervous and Mental Disease claims that there is a link between suicide and infection with this parasite. But of course, this occurred in people who already have a mental illness. Similarly, another study found that countries with high toxoplasmosis infection rates also had high suicide rates
In Denmark, A relationship has also been found between suicide and toxoplasmosis A joint investigation between the Danish National Hospital Registry and the Danish Central Psychiatric Research Registry found that women infected with toxoplasma were 54% more likely to attempt suicide, and were twice as likely to succeed.
In fact, these women were more likely to attempt violent suicides. But even more worrying is that the risk of suicide attempt was positively correlated with the level of infection. Those women with the highest levels of antibodies were 91% more likely to attempt suicide than uninfected women. The connection between the parasite and suicide held even for women who had no history of mental illness.