The parasitic way of life widespread in the animal world. The rabies virus produces a delirious rage in its dying host, causing the animal to infect new victims with its bite. The hairy worm Spinochordodes tellinii manipulates the brains of crickets, causing them to commit suicide by jumping into the water, where the worm can breed.
When the simplest Toxoplasma gondii enters the body of a rodent's natural fear of cat urine out. The smell of the predator begins to attract rodents, and when eaten, the parasite gets inside the cat's intestinal environment where it can multiply.
Dr. Jaroslav Flegr, a Czech researcher who studies parasites and their effect on humans.
Although Toxoplasma infects primarily rodents, humans do not have immunity to this parasite. Our life with cats provides the possibility for the penetration of Toxoplasma into our body. Since its opening in the early 1900s, protozoa were widely seen as relatively harmless passenger in the human body.
It was believed that the only threat existed against patients with a weakened immune system (e.g. AIDS) and pregnant women in the body which the parasite could harm the fetus or cause abortion. It was believed that a healthy person could suppress the parasite indefinitely. New evidence suggests the opposite. Through a delicate finessing of the neurotransmitters in our brain, in the place of those who are in control of, turned out to be you and me.
Dr. Jaroslav Flegr was the first who made this statement in 2002. By analyzing information on traffic accidents, the Czech parasitologist, found that the probability of getting into an accident, the drivers are infected with toxoplasmosis, 2.6 times higher than their healthy colleagues. Flegr sees a parallel between the risky behavior of infected rodents and high-risk behaviour are infected motorists. This feature of the scientist first noticed myself.
During his studies at Charles University in Prague, usually careful student of Jaroslav Flegr realized that he had suddenly become bolder. He stopped to look across the street and to pay attention to the blaring of car horns around him. He also began to openly criticize the Communist government, at a time when dissent was a crime.
This continued until his tests, which he passed in the framework of the research project to ascertain the reasons for his reckless behavior, has not tested positive for toxoplasmosis. If the parasite can alter the behavior of rodents, he reasoned, then why not humans too?
The flegr tested the theory by conducting surveillance of infected and healthy populations. In test after test, the results were consistent. Infected men were "more likely to disregard rules," and were more "suspicious, jealous, and dogmatic."
The traits of women was the opposite. They were more "warm", "responsive" and "moral". Ten years of research found no Association with various conditions such as ADHD (attention deficit disorder with hyperactivity), obsessive-compulsive obsessive-compulsive disorder, schizophrenia, and suicidal behavior.
I recently met with Dr. Flegr at his office in Prague to discuss how a tiny parasite living inside at least 10 percent of Americans and 30 to 50 percent of the population of the world can so profoundly change our personality. Why is the response to infection is so different in men and women?
Dr. Jaroslav Flegr: it is Known that men and women react in opposite ways to stress. So, it's possible that Toxoplasma induces chronic stress, and that men and women react differently to the same stimulus. Interestingly, the behaviour of infected women, as a rule, has positive features.
When women experience stress, they begin to show friendly feelings. They are looking for a company. That is why we believe that people get infected with this sore well. [Laughs] But that's not true. It's just a defensive strategy. I've read that some women actually want to become infected.
Yes, but I don't recommend it. Have they asked you to infect them?
Sometimes I'll get an email like that, but it's mostly men interested in infecting their friends. Because it makes women more promiscuous?
This is actually not true. Journalists draw conclusions from my findings. My recent research shows that it decreases libido in women. How about the influence of the parasite on the sexual desire in men?
It seems it has no effect. It's weird, because the parasite has a very strong impact on women but not affect men. I believe there are two processes that compensate each other. One of them is that in patients with reduced sexual desire; the other is that Toxoplasma is known to increase the concentration of testosterone in men. So you might think that the sex drive increases. Are we just collateral damage in the life cycle of the parasite, or the changes we undergo and bring him some benefit?
A few thousand years ago we were part of the life cycle of Toxoplasma. Even now many people die as the result of tigers and lions in some parts of the world. Perhaps, in fact, manipulation of the parasite, primarily aimed not at rodents and primates. Do you think that the influence of toxoplasmosis increases the chances of a person to be eaten by a lion or tiger?
Yes. Some effects of toxoplasmosis really increase the risk. In our questionnaire, positive people report that they began to feel less fear compared to healthy people. We asked how much they are afraid to be in a dark forest, for example, and they say that they are not too scary. They also traced a weaker reaction to fear. When infected people cross the street and a horn blows, they don't skip away. [Laughs] It's not a good strategy if you are being attacked by tigers or lions. If toxoplasmosis is in relation to schizophrenia, obsessive and suicidal state, then these States can isolate the person from his social group and, thus, make it more vulnerable to being eaten by a big cat.
It is possible that this may be the reason. As in the case of rodents, in humans too, there is a attraction to cat urine?
Yes, we observed this fatal attraction phenomenon in humans. Infected men rated the smell of very diluted cat urine as more pleasant. It was a double-blind study. People did not know whether they were infected, and they didn't know what they were smelling. We used the 12 urine samples from different animals, and our subjects had to vote for the pleasantness of the smell. After analyzing the results, we got a pretty clear picture. I spoke with a student-master, Charlie Nichols, and he asked whether the attraction to the smell of cat urine is one of the reasons why people love to have cats.
Possible. At least if someone doesn't like this smell, it won't keep cats. Smell plays a very important role in our lives. We don't realize this, because it's mostly subconscious reactions, but love is a question of smell. Very often, the smell is the cause of our love to someone.Do you think toxoplasmosis plays a role in the emergence of love?
Toxoplasma changes our sense of smell quantitatively and qualitatively. There is not enough data, but there is some indirect evidence of this fact. It is known that schizophrenics changes the sense of smell. Smell, who had previously been pleasant, starts to push. Many data show that a large percentage of schizophrenia is caused by toxoplasmosis. What is the evidence for that?
Is the current study, the results of which show that antibodies to Toxoplasma appear in the blood of patients for 6-36 months before the start of schizophrenia. In many cases, schizophrenia is triggered by and may be caused by Toxoplasma. Of course, it's rare. The frequency of toxoplasmosis is about 30 percent, and the frequency of schizophrenia is about one percent. So most people who are infected by toxoplasmosis do not get schizophrenia. And you do have toxoplasmosis, right?
Yes.How did you get infected?
There were several possible sources. I spent over a year in Japan, I ate a lot of raw meat, so maybe there. How did you feel when you found that out?
I'm not very happy about this. But a lot of people in our ward were also infected, somewhere around 30 percent. Now, the prevalence of toxoplasmosis among our students is about 10 percent. This is due to better hygiene?
Possible. Maybe this is due to a change of rules for cleaning children's sandboxes. The sand must be replaced quite often. There are other options. For example, our recent research, the results of which we are preparing for publication, showed that Toxoplasma gondii can be transmitted sexually. It is possible that in connection with the AIDS epidemic, unprotected sex has become less popular, and correspondingly decreased the percentage of infection by toxoplasmosis sexually. Do penetrates Toxoplasma gondii in the semen and vaginal?
In some species we found parasites in the semen. And about two thirds of the cases the fetus is infected, we could not find any risk factors. The mother did not eat raw meat, she washed vegetables, she behaved very reasonably. There were no risks, and yet she became infected. So it is possible that infection occurred during unprotected sex with her husband. Have you checked whether the husband is infected with?
While we have no data on this, but we will check. Can the infection be transmitted from women to men?
I believe that the transmission goes only from men to women, at least mostly so. Do you think that the increase of testosterone in infected men is a way of toxoplasmosis to increase your sex drive to facilitate its distribution?
Maybe. In the book the Selfish gene, Richard Dawkins mentions the possibility of increasing libido in patients with syphilis. I read that HIV can also cause growth sexual desire.
I think chlamydia can also provoke it. I understand that the percentage of patients with toxoplasmosis varies from country to country. In my opinion, the countries of Latin America have the highest, while South Korea has the lowest. Do you think that toxoplasmosis could affect behavior on a national level?
I believe this impact. It was already published by another parasitologist that national characteristics can be partially explained by frequency of infection with toxoplasmosis among the population. This year, we published a very important paper showing that the frequency of many diseases can be explained by differences in the prevalence of toxoplasmosis. Our data show a strong Association with epilepsy and cerebrovascular diseases, including heart attacks. In Europe, this can explain about 16 or 17 percent of all heart attacks. If we were able to find a cure or a vaccine against toxoplasmosis, it could save many lives.
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As our interview drew to a close, I asked Dr. Flegr if I could photograph him for this article. He agreed, joking, "Sorry, I have no cats to hold hands".
While looking into the viewfinder, I noticed how his smile quickly disappears. The mood had suddenly changed.
"I think that's enough," he snapped. "My friend once told me that if a journalist uses this kind of lens, it means he wants you to seem ugly in the photos. It's a standard journalistic trick when shooting politicians they don't like them".
I tried to squeeze out what I hoped would look like a reassuring smile. "Not at all, doctor. I'm just trying to make a good photo".
"But you have a fixed-focus camera," he countered. "Our studies show that the use of different lenses in the attractiveness of people in photos".
We shook hands and said goodbye stiffly, but it seemed more like a wish "good riddance". I walked through the empty halls of Charles University, reflecting on the sudden impulse of suspicion, which had just seen. Where did it come from? Was it Flegrei or the impact of Toxoplasma? Although, what's the difference? published
Author: Rock Maureen