Once someone in the family gets pregnant, pet cats will often become the first victim and be abandoned, so cats are often nicknamed "If you have children, you don't want me anymore."
The main reason is that people are afraid that the toxoplasma gondii that may be carried on pet cats will be transmitted to unborn children.
Toxoplasma gondii is probably one of the most common parasites known in the world. They can parasitize almost all warm-blooded animals. For birds, all wild birds except one kind of wild duck have cases of infection. The same is true for mammals. All mammals from the ocean to the land have cases of infection. For humans, at least 2 billion people have been infected with Toxoplasma gondii (up to 50% of people may be infected).
Toxoplasma gondii ©Dr_Microbe
At the same time, Toxoplasma gondii is probably one of the most mysterious and interesting parasites because they are observed to affect the behavior of the host, and we have very limited knowledge of them.
So what kind of parasite is Toxoplasma gondii, why can they spread so unscrupulously, do we have a way to deal with it now?
How does Toxoplasma gondii spread?
In fact, it is undoubtedly self-deception to abandon the cat until you get pregnant, because it is never the cat that transmits Toxoplasma gondii to the fetus, but the mother himself is a carrier of Toxoplasma gondii - The only way to "human transmission" of Toxoplasma gondii is placenta .
We humans, as well as most other warm-blooded animals, are just intermediate hosts of Toxoplasma gondii, and their final host is felines. 17 species of felines have been found to be the final hosts of Toxoplasma gondii, including our pet cats.
Toxoplasma gondii will only reproduction in felines, while in all other warm-blooded animals considered intermediate hosts, Toxoplasma gondii will only reproduction in asexually .
Toxoplasma gondii is a protozoa whose main way of survival is parasitics.
The main closed loop of their parasites is: felines eat the intermediate host carrying Toxoplasma gondii, and then they complete sexual reproduction in the feline, and excrete it out of the body in the form of an oocyst, and then be ingested by the intermediate host and transmitted to the feline, thereby circulating .
Toxoplasma gondii's oocyst is a thick wall wrapped with fertilized eggs, and its survival ability is relatively tenacious. In the soil, water, fruits and vegetables contaminated by feline feces, etc., the oocyst can survive for several months (even in seawater for 6 months) until an intermediate host or other feline ingestion is included.
The oocyst of Toxoplasma gondii enters the feline family and the intermediate host initially undergoes almost the same experience. Both the cyst walls are dissolved by the proteolytic enzyme in the stomach and small intestine and releases sporophytosus , and then begins to invade nearby cells.
However, as the final hosts, they are significantly less sensitive to Toxoplasma gondii oocysts and will be more easily accomplished with initial parasitism.
When they just invade new host cells, their activities will be very active and reproduce very quickly, so this stage is called speed seeds.
Toxoplasma infection is divided into three stages, and the merozoite is the first stage of Toxozoite infection. In this stage, the specialized vacuoles produced by the host cell membrane - called parasitic vacuoles, completely wrap themselves up and quickly copy themselves inside until the host cell dies and releases the merozoites, which then they spread to all tissues and organs through the blood circulation, including the brain .
Figure: Rapid melon division
As the spread of Rapid melons, our immune system can no longer sit still. At this time, the immune response will become very strong, and sometimes the host (human) will have a high fever.
At this time, Toxoplasma gondii also has a very smart survival strategy. They will not be positive with our immune system, but will enter the second stage - slow-merozoite .
In the slow-melt stage, they will form clusters of cysts in our tissue cells - called cysts , and also wraps itself with a bubble film, which is a bit like adding an invisible effect, which can avoid being cleared by the immune system by .
Figure: The proliferation rate of slow-merozoite in mouse tissues
slow-merozoites is very slow, so they coexist peacefully with the host in the host. At this time, as long as the immune system is normal, the host will basically not have any problems.
It is worth mentioning that although slower melanocytes can parasitize in any tissue, their favorite places are brain, eyes and striatal muscle (including the heart) - firmly grasp the most important organs of the host.
Intake of cysts and ovum cysts may cause warm-blooded animals to be infected with Toxoplasma gondii. ovum cysts are mainly found in water and soil, and contaminate some vegetarian vegetables and grasses. cysts exist in the intermediate host. As long as you eat these uncooked meats, you may be infected with .
If the cat eats both, Toxoplasma gondii will develop sexually in its body and produce the third stage of Toxoplasma - the oocyst, which no other intermediate host will.
's diverse transmission methods and the parasitic strategy that "does not harm" the host may be the reason why Toxoplasma has become the "number one" in the parasite world.
The mouse that is controlled by Toxoplasma gondii
We mentioned earlier that one of the places where Toxoplasma likes parasites the most is the host's brain, so Toxoplasma gondii is indeed likely to affect the host's behavior to some extent. At the same time, manipulating the host is definitely of evolutionary significance for Toxoplasma gondii.
Since felines are the only final host of Toxoplasma gondii, what they most hope to do is to infect more felines to complete effective gene transmission.
The cat family is the top predator, and cysts are an important way of transmission for Toxoplasma gondii. As long as Toxoplasma controls the host slightly and makes it easier for feline animals to eat hosts carrying cysts, they will actually easily achieve greater success.
Many studies have found that the situation is basically in line with this speculation - Toxoplasma gondii will make the intermediate host more likely to be eaten by felines .
Source: Wendy Ingram/Adrienne Greene
In the study of rats, rats infected with Toxoplasma were less averse to cat urine, and at the same time they developed X-excited to cat odor.
However, in the study of mice, no unique choice was found for cats, but mice infected with Toxoplasma reduced anxiety, increased exploration behavior, and general loss of disgust for all predators.
Whether it is a separate choice for cats or a common choice, infection with Toxoplasma will make the intermediate host more easily eaten through some methods, which is basically certain.
In some human studies, the possible impact of Toxoplasma gondii on us has also been found, including the risk of traffic accidents among Toxoplasma infected people is 2.65 times higher than that of ordinary people, the history of mania and depression is 2.4 times higher than that of ordinary people, and the situation of choosing to start a business independently is 1.8 times higher than that of ordinary people.
In fact, there are many related studies. Toxoplasma gondii will reduce the host's compliance, increase behaviors such as irritability and exploration, and significantly increase in mental diseases (such as schizophrenia).
However, the impact of Toxoplasma on humans is still considered non-mainstream and lacks evidence, so just take a look, don't be too serious.
Although the impact of Toxoplasma infection on human behavior (if it really exists) is not necessarily completely negative, this thing is 100% thunder in the body.
Source: SamKakeru/Fruit Keel
For people with normal immune system, Toxoplasma gondii in the form of cysts will not have any health risks for a long time, but once there is a problem with the immune system, it may be fatal to the infected person.
Because the baby's immune system is relatively weak, Toxoplasma gondii does have a greater impact on babies. It is understandable that some people do not contact cats after pregnancy.
So, is there a way to cure the infection of Toxoplasma gondii?
, as far as we look at it, shouldn't be there. Human drugs ( antibiotic , etc.) can easily kill Toxoplasma gondii, so it is easy to treat acute infection, but it cannot completely remove the cysts. As long as Toxoplasma forms cysts in tissue cells, it will accompany the host for a lifetime.
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