Toxoplasma gondii is a single-celled parasite that lives in mammals and birds. It’s a common parasite in humans. Our immune system usually keeps a T. gondii infection under control and prevents any health problems from developing. Some people experience flu-like symptoms from a Toxoplasma infection, however. This disease is known as toxoplasmosis. Sometimes the parasite enters the brain, where it may affect brain chemistry and alter a person’s behavior.
Toxoplasma gondii are small parasites, affecting humans with a weak immune system. These parasites can also affect a cat. Proper handling of food, and regular cleansing of litter boxes prevents the transfer of these parasites. Common symptoms include painful urination or blood in the piss.
Let’s widen this tapeworm topic
Taenia solium is another parasite which causes health problems. It enters the body when we eat undercooked pork that contains tapeworm larvae. A larva attaches itself to the wall of the small intestine and grows into an adult. The tapeworm survives by absorbing food that we have digested.
More Info About Tapeworm
If we ingest tapeworm eggs, cysts containing larvae may appear in our brain as well as in other areas of the body. A larval cyst is known as a cysticercus and the occurrence of cysts in the brain is known as neurocysticercosis. The cysts can cause seizures, epilepsy and other serious problems.
Tapeworms in dogs do affect the human health. As the immune system of children isn’t fully developed, they’re more vulnerable to parasitic infections. If humans ingest the tapeworm eggs, they can travel to the intestines. The larvae will hatch and make hydatid cyst in the liver, kidneys, brain, lungs, or other organs. In extreme cases it may cause organ failure or cyst rupture which can even result in death. It is advisable to wash meat, fruits, and vegetables before cooking or eating as food contaminated with dog feces can also cause tapeworms.
Although the body of Toxoplasma gondii consists of only one cell, this cell has a complex structure and behavior. T. gondii is very well adapted for life as a parasite. It lives inside a cell of another organism and absorbs nutrients from this cell. The parasite takes just a few seconds to write a host cell.
The primary host of the parasite is a wild or domestic cat. The cat is called the ‘primary’ host because the parasite undergoes sexual reproduction inside the cat’s body. Rodents (especially rats and mice), birds, humans, and other warm blooded animals are said to be intermediate hosts of the parasite. The parasite undergoes asexual reproduction in the intermediate host’s body. The parasite must move from its primary host to an intermediate host and then back to its primary host to complete its life cycle.
The Toxoplasma parasite has a complex life cycle. The parasite exists in three different forms-the sporozoite, the tachyzoite and the bradyzoite. The sequence of developments in the life of T. gondii is as follows.
Toxoplasma leaves a cat’s body in a form known as an oocyst. The oocysts are published in the cat’s feces. They have a tough, protective wall and may survive in the environment for longer than a year.
If a person (or an animal) comes into contact with an infected cat’s feces, oocysts may enter the person’s body. Contact may occur by touching cat feces or by eating or drinking items contaminated with the feces, such as plants and water.
In the human or animal’s intestine the oocysts become active and release sporozoites. The sporozoites penetrate the lining of the intestine, then enter the host’s cells.
Once inside host cells the sporozoites produce tachyzoites, the form that produces the symptoms of toxoplasmosis.
Tachyzoites burst out of the host cell, destroying it, and then enter new cells, where they reproduce rapidly. The cycle of reproduction and destruction is repeated many times, unless the host’s immune system is able to bring an end to the process.
Bradyzoites multiply slowly, unlike tachyzoites. They are placed inside a cyst. This is sometimes known as a tissue cyst to distinguish it from an oocyst. Tissue cysts tend to form in particular parts of the body, including the brain, the heart, the eyes, and the skeletal muscles.
The tissue cysts become dormant and may stay where they’re formed for a number of years-perhaps the same for the life of their host. However, the cysts may sometimes get out of their dormancy and release the cells inside them. These infect new cells.
If a cat eats an animal part containing tissue cysts, the cysts become active in the cat’s intestine. The parasites invade the intestinal lining, producing male and female reproductive cells. These cells join to make a zygote. This becomes an oocyst. Then the cycle begins again.
Most cats and humans do not get sick when they have a Toxoplasma infection. The immune system limits the proliferation of the tachyzoites through the body and no symptoms arise from the infection. Other people may experience the aches and pains of mild flu before these symptoms disappear and the parasite enters a dormant state. However, cats and humans in a vulnerable stage of life may exhibit far more serious symptoms.
In humans, the individuals that are more likely to experience major effects from a Toxoplasma infection are people with weakened immune systems and the fetuses of pregnant women. The parasite may be very dangerous in AIDS patients or in people taking drugs that suppress the work of the immune system, such as organ transplant patients. During pregnancy Toxoplasma can go through the placenta and cause birth defects in the developing baby. It may even kill the baby.
More than 60 million people are chronically infected with Toxoplasma gondii, the parasite that causes toxoplasmosis. New infections in pregnant women can cause birth defects. Infections in people with weakened immune systems can be deadly.
Health experts declare that it certainly is not necessary to eliminate a pet cat from a family when someone in the home is susceptible to getting sick from a Toxoplasma infection. However, it is extremely important to take certain precautions.
Pregnant women (or other people at risk) should avoid cleaning cat litter or should wear plastic gloves when they deal with the litter tray. In addition, the litter should be cleaned frequently. The oocysts are shed into the cat’s feces in an immature state. It takes at least a day for the sporozoites to form in the oocysts, and normally takes between 2 and 5 days. Cleaning the litter frequently reduces the risk of a dangerous infection.
Pregnant women should be very careful when gardening because they may touch old cat feces released by wandering cats. This feces may contain mature oocysts. Plants should be washed thoroughly before being eaten.
Vulnerable people should also make sure that all meat is thoroughly cooked and that they maintain good kitchen hygiene, avoiding the contamination of items with raw meat or its juices. Raw meat may contain T. gondii.
Rodents are the main intermediate host of Toxoplasma. The parasite has an amazing impact on a rat or mouse’s behavior. These animals are usually fearful of a cat’s scent, since the cat preys on rodents, and will run away from any cats in the area. However, a rodent infected with Toxoplasma loses its fear of cats and is actually attracted to them. This means that the rodent is more likely to be caught and eaten by the cat. This allows the parasite to go into the cat’s body and continue its life cycle.
Researchers have revealed that the parasite triggers the rodent brain to produce a much greater amount of dopamine than normal. Dopamine is a neurotransmitter-a material that enables a nerve impulse to pass from one nerve cell to another or that influences this transfer.
One scientist has found that T. gondii contains genes that code for an enzyme involved in dopamine production. Dopamine has no known function in single-celled organisms. In addition, the scientist found that when rats infected by T. gondii were injected with a medication that blocks dopamine receptors, they were no longer attracted to the scent of cats. Since rats and humans are both mammals, scientists wonder if T. gondii affects the dopamine system in humans too.
Although the connection between Toxoplasma in the human brain and behavior changes is not confirmed, the list of observations that support this respect is growing. Some of the observations are based on lab experiments. Others are based on epidemiology studies in which researchers record Toxoplasma levels in people’s bodies as well as their disease states, behavior traits or other areas of their lives.
Researchers have discovered that people with schizophrenia, depression and anxiety syndrome are more likely to have a Toxoplasma infection than people without these conditions. We need to be careful when interpreting these results, however. They may indicate that Toxoplasma causes the disorders. However, they could indicate that when people suffer from the disorders they’re more sensitive to a Toxoplasma infection.
In one lab experiment Toxoplasma was injected into human dendritic cells in a container. Dendritic cells are an essential part of our nervous system. Once they were infected, the dendritric cells started to produce GABA (gamma aminobutyric acid), a major signaling molecule in the nervous system.
The researchers found that when dendritic cells infected with T. gondii were fed into the brain of living mice, they influenced the brain’s GABA system.
Surveys suggest that people with the parasite in their bodies are taking part in more traffic accidents, whether they’re drivers or pedestrians.
One survey found that people with a Toxoplasma infection were less conscientious than those without Toxoplasma. Another found that infected people had shorter attention spans.
Some scientists think that Toxoplasma may affect its host even though the parasite is in its ‘dormant’ or latent phase.
The pork tapeworm lives in the human intestine, despite its name. Taenia solium has a flat, ribbon-like body which is segmented and white in color. At one end is a structure called the scolex. This is used to attach the tapeworm to the intestine. It has four suckers, each of which has a double row of hooks. The adult tapeworm may have as many as 800 segments. These are known as proglottids. The proglottids at the end are the most mature and contain both male and female generative organs. Eggs are fertilized in these proglottids. The terminal sections of the tapeworm’s body are shed and pass outside of the person’s body in the feces.
When a pig eats food contaminated by proglottids or fertilized eggs, the eggs develop into embryos known as oncospheres. These travel through the intestinal wall and enter the pig’s circulatory system. This carries the oncospheres to muscle. Here an oncosphere changes into a larval form known as a cysticercus. The larva is embedded in a cyst. When humans ingest the pig’s muscle as meat, the cysticercus is not digested but attaches to the wall of the intestine and grows into an adult tapeworm.
If a human ingests tapeworm eggs instead of the cysticercus larva, the result of the tapeworm infection is very different. As in the pig, the eggs develop into oncospheres. This burrow through the lining of the intestine, then enter the circulation. In humans the oncosphere develops into a cysticercus in the brain, lung, or eye as same as in heart and skeletal muscle. The presence of cysticerci in the brain is called neurocysticercosis.
The primary source of getting a tapeworm infection is through the tapeworm eggs (cysticercoids) present in the fleas feeding on the cat. These eggs hatch in the intestines where they grow into adult tapeworms.
Cats are commonly infected by five types of tapeworm species. The manner in which such species of tapeworms infect the cat is different.
Dipylidium caninum is the most frequent type of tapeworm found in cats. It infects cats when they ingest fleas which have larvae of tapeworms present in them.
The symptoms of neurocysticercosis can be very serious and include seizures and acquired epilepsy. A doctor at the National Institutes of Health estimates that at least 5 million cases of epilepsy in the world are caused by a pork tapeworm infection in the brain.
As a cyst enlarges it pushes against brain tissue, preventing it from working properly. Cysts may block passageways for the cerebrospinal fluid that circulates through and over the brain. This can give rise to a condition called hydrocephalus. This is sometimes known as ‘water on the brain’. Fluid builds up under the skull, putting strain on the brain and damaging it. The increased pressure may cause a brain hernia, a condition in which a portion of the brain is pushed away from its normal position. This is a medical emergency since it can result in a coma and death.
If the immune system attacks the cysts the brain may become inflamed. This can lead to blindness, seizures, meningitis or other serious conditions. Meningitis is inflammation of the membranes covering the brain. These are referred to as the meninges. Untreated meningitis may be fatal.
There are treatments for acute toxoplasmosis (the condition is which the symptoms are obvious) and for neurocysticercosis. However, in areas such as North America it is easier to prevent these diseases than to treat them. This is especially true for neurocysticercosis. This requires treatment over an extended period of time and with greater than one medication in order to handle the disease.
Both Toxoplasma gondii and Taenia solium can cause symptoms ranging from minor to deadly. They are of major concern not simply because they can kill people but also because the first parasite may affect our behavior and the other is widespread and very common in some countries.