Toxoplasma gondii is a parasite with its own special rules of life, which also determines that its transmission route is different from that of bacteria or viruses. Many people do not understand this, and it is not right to have an endless fear of small animals in their daily lives.
Trophozoites are proliferative forms of Toxoplasma gondii, divided into intracellular and free types, which multiply spontaneously in the body of acute infection and can occur in both intermediate and final hosts. Trophozoites during acute infection multiply within host cells and contain dozens or even hundreds of worm bodies. The outer membrane of this insect body is surrounded by host cells and is not formed by the secretion of protozoa, so it is called a pseudo-cyst. The worm body emitted after the rupture of the pseudocapsulum is an endomorph, also known as a tachyrozoite.
Cysts, the main form of infection, can occur in both the intermediate host and the terminal host, often formed in the brain, muscle and other tissues of chronically infected animals, and contain hundreds or even thousands of insect bodies. The cyst can survive in the tissue for a long time, even with the host for a lifetime. The cyst will rupture under certain conditions, the insect body will overflow into a cyst, and multiply in the tissue to become a new cyst.
Oocyst: present only in the end host. Immature oocysts contain one sporangia, and mature oocysts contain two sporangia. Each sporangia contains 4 sporozoites.
Mesosomes: After the sporozoites enter the epithelial cells of the mucosa of the small intestine of the final host, before the gamete reproduction begins, the worm body proliferates through the internal two buds, the endoproliferation, the fissured proliferation, etc., and eventually becomes multiple worm bodies, that is, the fission. After the schizoite ruptures, the merozoite invades into the new host cell and continues to proliferate into the next generation of myrosomes.
Gametophytes: after the toxoplasmosis mesozoa invade the mucosal epithelial cells of the final host small intestine, they do not form a schizoite, but develop into two kinds of gametophytes, large and small. Small gametes mature to form 12 to 32 male gametes.
Toxoplasma gondii has a dual-host life cycle that develops in two phases, extraintestinal and intraintestinal, respectively. Asexual reproduction occurs in the extraintestinal stage, developing in various intermediate host (e.g., mammals and birds) and final host (cats and felines). In the intestinal phase of development, there is both asexual and sexual reproduction, but only in the epithelial cells of the mucosal mucosa of the terminal host. The entire life history can be completed in cats and felines, but only asexual reproduction occurs in animals and humans other than cats. The total life history is divided into 5 stages, namely the trophoblast stage, the inclusion phase, the fissile phase, the gametophyte phase and the oocyst phase. The first 3 stages are asexual reproduction, and the last 2 stages are sexual reproduction. Asexual reproduction can cause systemic infection, while sexual reproduction creates a local infection in the intestinal mucosa.
Medical students who have studied parasites should be able to understand the life habits of Toxoplasma gondii after reading this text. But the layman is still in the clouds and fog, unable to understand. In fact, you only need to understand the following words:
The trophozoite of Toxoplasma gondii is its pathogenic state, and the cyst is an insidious state. Cysts are present only in the host cat.
Humans are infected with Toxoplasma gondii in two ways: one is the infection with the feces of the sick cat, and the other is the consumption of the meat of the infected animal containing the sac (such as uncooked lamb, pork, bird meat) and other infections. For example, a cat can be infected with Toxoplasma gondii, but a dog will not be infected through this route, and even if the dog is infected with Toxoplasma gondii, it will not be infected unless the dog is killed and eaten, and the dog meat is not cooked. Eating pork that is not cooked is also true.
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