Toxoplasmosis: what it is, in pregnancy, symptoms and treatment


What is toxoplasmosis?

Toxoplasmosis is the infection caused by a protozoan called Toxoplasma gondii and can also be known as “cat disease”, because the animal is the definitive host of the pathogen.

About 80% to 90% of infected people have no symptoms, or, when they do, they resemble those of the flu . However, when the disease is acquired during pregnancy or by someone with compromised immunity, the symptoms can be more severe, and can even lead to death when not diagnosed early.

The Toxoplasma gondii  was discovered in Tunisia in 1908 by Nicolle & Manceaux and was known as ctenodactylus gondii . A year later, that is, in 1909, the researcher differentiated this protozoan from the cause of Leishmaniasis and, then, gave it the name it brings today.

The causative agent of the disease is present in the four corners of the world, but the disease itself has very different incidence rates depending on the country. According to the International Journal for Parasitology, a survey of 99 studies, carried out in 44 different countries, found that the percentage of prevalence of the disease is as follows:

  • Latin America: 50% to 80%;
  • Central and Eastern Europe: 20% to 60%;
  • Middle East: 30% to 50%;
  • Southeast Asia parts: 20% to 60%;
  • Parts of Africa: 20% to 55%.

In March 2018, an outbreak of toxoplasmosis began in the city of Santa Maria, in Rio Grande do Sul. In three months, more than 569 cases were confirmed and another hundred were under investigation.

There are suspicions that the method of contagion has been through water and poorly washed food. More than 50 pregnant women have already had the disease confirmed and another 145 have symptoms being investigated, which can cause serious problems for pregnancy.

Parasite cycle

The parasite’s life cycle begins in felines. The Toxoplasma gondii live in the intestines of cats and releases oocysts  (which may be called parasite eggs), which are the cat’s feces. In a humid environment, oocysts can survive for up to five years waiting for the intermediate host.

This intermediate host can be almost any animal that consumes oocysts in any way, whether it is a pig feeding on the cat’s feces, whether that soil is used in plantations or through direct contact. If the oocysts are on a sofa, for example, a human can come in contact with them and take them to the mouth.

From this consumption, the oocysts try to infect the host, transforming themselves into tachyzoites It is at this moment that the patient goes through the acute phase  of the disease, which is not always manifested through symptoms .

Tachyzoites spread throughout the host’s body, but the immune system forces them to turn into bradyzoites, which form small cysts to protect themselves from the immune system.

When a feline feeds on this animal – for example a lion eating infected cattle or a domestic cat eating an infected mouse – microscopic cysts are ingested.

In the feline intestine, parasites complete their life cycle. Bradyzoites mature and become Toxoplasma gondii , to start the cycle again through oocysts that will be poured into the feces.

When the cysts are not consumed by the cat, they stay in the tissue of the intermediate host, usually inert, since the immune system usually keeps it that way for long periods.

Zombie Rats

A small curiosity: when Toxoplasma  gondii infects mice, it can cause damage to the rodent’s brain that causes it to lose its fear of cats and daylight. This makes it easier for the mouse to come into contact with cats, without running away, facilitating the parasite’s cycle.

Types of toxoplasmosis

There are, in general, 5 types of toxoplasmosis, which differ due to the stage of infection, context and location. Understand:

Acute toxoplasmosis

Acute toxoplasmosis is the active part of the disease. In the parasite cycle, it is the time when the cysts are forming in the tissues. People with strong immune systems ( immunocompetent ) may have few or no symptoms at this stage, which in a few weeks progress to latent toxoplasmosis.

The symptoms of this phase affect only 10% to 20% of infected immunocompetent patients. There are risks for people with compromised immunity, such as HIV patients and people undergoing treatment for autoimmune diseases , for example.

Latent toxoplasmosis

Latent toxoplasmosis occurs after the acute phase, after the cysts settle in the tissues and wait for a feline to consume them. The active immune system ensures that they stay where they are and normally, from there on, there are no more consequences for the body, which even becomes immune to new infections.

Ocular toxoplasmosis

Ocular toxoplasmosis occurs when the parasite affects the eyes, which may be in the iris or the retina. It is a type of toxoplasmosis most common when congenital infection occurs, but in rare cases it can affect immunocompetent adults as well.

This type of toxoplasmosis can cause blurred vision, eye pain, sensitivity to light and eventually lead to vision loss.

Congenital toxoplasmosis

Congenital toxoplasmosis is contracted by the baby through the mother. One of the major concerns with toxoplasmosis is the infection of pregnant women, as the parasite can infect the fetus through the placenta.

This only happens when the mother is in the acute stage of contamination during pregnancy. There are tests that detect and differentiate the condition and it is possible to know if the mother has been infected or not during her life before pregnancy.

When there has been previous contamination, there is no concern, as the mother will not develop the active phase of the disease again, which means that the child will not be infected.

However, if the mother has never been infected, care must be taken so that this does not happen during pregnancy, since the fetus, as it does not have a well-formed immune system, can present severe symptoms.

Cutaneous Toxoplasmosis

As rare as it is, skin toxoplasmosis can occur and cause damage to the epidermis. These lesions are so small that, in order to be identified, an electron microscope is required.

Causes of toxoplasmosis

Toxoplasmosis is caused exclusively by the protozoan Toxoplasma gondii , which is a parasite that inhabits the intestines of cats, but uses other animals to grow and reach the cat that will be the definitive host.

Transmission of toxoplasmosis

Depending on the region analyzed, the rate of infected adults can be incredibly high since Toxoplasma gondii  is widespread in nature. The state of São Paulo, for example, has more than 70% of the population already infected by the disease at some point in the past and France reaches almost 100% of the population with latent cysts in the muscles and other tissues.

In general, toxoplasmosis is not contagious among humans. This means that a person cannot pass the disease on to another person. Transmission of the disease to people can occur in a few different ways. Check out:

Direct contact with cat feces that contain the parasite

Sometimes, accidentally, you can ingest the parasite when it touches the mouth after gardening, cleaning the animal’s litter box or touching any object that has come in contact with the feces.

Ingestion of contaminated water or food

Raw or undercooked meats can be susceptible to the transmission of the parasite to the human body. Unpasteurized foods can also present it occasionally. This is because it is possible that, on a farm with cats, animals are contaminated.

Ingestion of unwashed fruits or vegetables

It is recommended to always wash fruits and vegetables well before consuming them. If the cat defecates near a crop, the parasite may end up in the food.

Use of contaminated utensils

Food utensils that come into contact with contaminated raw meat can also be a means of transmission. All the more reason for you to obey your mother and fix that pile of dirty dishes in the sink.

Placental transmission

Toxoplasmosis can be transmitted from the mother to the child through the placenta during pregnancy.

Organ transplants or blood transfusions

In rare cases, blood transfusion and organ transplantation can also be a means of transmitting the disease and this is the only way for a human to catch another human’s disease.


The transmission of toxoplasmosis through pigeons is possible since, if infected, they can release the parasite through the fluids of the eyes. However, because very close contact with the bird is necessary, this is a rare form of contamination.

Risk factors

Anyone is liable to develop toxoplasmosis. Some groups, however, are at greater risk, both of contagion and of the development of symptoms. Are they:

Living with cats

Owning cats, especially those allowed to leave the house, is a risk factor, after all, these animals will hunt when they are on the street and can come into contact with the protozoan more easily.

When they cannot leave the house to hunt, the chances of contamination are less, but it is still possible for them to catch the disease through food if owners give uncooked meat, just like humans.

Visiting houses with cats also increases the chances of contamination if you have never been infected before, but it is important to remember that cats are not the villains  of the story.

The parasite’s oocysts are only excreted for approximately two weeks after the cat is infected and after that, there will be hardly any new excretion since, like humans, cats develop immunity to infection.

Eat rare meat

Although cats are the definitive host of toxoplasmosis, rare meat is the main form of contamination. France has almost 100% of the adult population with past toxoplasmosis because mutton is widely consumed there and this is an animal that is frequently infected.

Southern Brazil has almost 90% of the adult population infected due to high meat consumption.

Being a carrier of HIV

People who have the HIV virus have a compromised immune system. A toxoplasmosis infection in these people is much more likely to be symptomatic.

Perform chemotherapy

Because it affects the patient’s immune system, the body of patients undergoing chemotherapy cannot fight infections that may eventually spread throughout the body.

Thus, an infection with Toxoplasma gondii  can develop symptoms.

Taking steroids or other types of immunosuppressive drugs

As with chemotherapy, these types of medications weaken the immune system, making it impossible for the patient to fight infections. These drugs are used for allergic reactions, autoimmune diseases, in addition to organ transplants, to combat rejection.

Symptoms of toxoplasmosis

Symptoms of toxoplasmosis rarely appear. Only about 10% to 20% of infected patients show symptoms, but when they do, they can resemble the flu. Are they:

  • Fever;
  • Headache;
  • Discomfort;
  • Muscle aches;
  • Sore throat.

Swollen lymph nodes

Lymph nodes can be located behind the ears, on the back of the neck, armpits and inguinal regions (between the hip and the thigh). In some cases of symptomatic toxoplasmosis, these nodes may swell and become tender and painful.


Acquire toxoplasmosis during pregnancy as it is a problem. The parasite can affect the fetus, causing deformations and consequences for pregnancy.

Although the patient may not have any symptoms of the infection, toxoplasmosis may increase the risk of:

  • Spontaneous abortion: loss of pregnancy during the first 23 weeks;
  • Fetal death: birth of the baby after 24 weeks without vital signs.

Congenital toxoplasmosis (in babies)

When the disease is transmitted from mother to child, some symptoms can strike the child. They vary according to the date the mother was infected and are usually more severe than hers. Understand:

  • If the mother is infected for the first time before or during pregnancy, the disease can be transmitted congenitally, even if she has no symptoms.
  • If the mother is infected in the third trimester of pregnancy, the greater the risk of transmission of the disease to the baby. If she becomes infected in the first trimester, these risks are less, but if it does, the effects of the disease on the fetus will be more severe.

When the baby does not have a miscarriage or is stillborn, he can be born with serious complications, such as:

  • Convulsions;
  • Enlarged liver and spleen;
  • Yellowing of the skin and eyes (jaundice);
  • Serious eye infections.

Often, these symptoms do not appear in children until their teens. However, in a small portion, this happens, so it is important to be aware of any different signs in the child.

Immunocompromised patients

One of the cases in which toxoplasmosis may be at risk is when the patient is immunocompromised, such as HIV carriers, patients undergoing chemotherapy and transplantation.

The immune system of these people is not able to contain the cysts and the parasite does not find barriers in the body. The treatment of these conditions must be quick to avoid further damage.

Toxoplasmosis in immunocompromised patients can cause problems such as:

Severe encephalitis

Damage to the central nervous system can be caused by encephalitis due to toxoplasmosis. When cysts are not properly contained by the immune system, they can affect the brain and cause inflammation of the brain.

Depending on the affected area, symptoms can range from paralysis to hallucinations, including headaches, language problems, drowsiness, mental confusion, among many others.

Because the brain controls the entire body, inflammation in it can cause a huge variety of symptoms that can be especially dangerous.


Pneumonitis is a parasitic infection of the lungs. Like encephalitis, this disease is caused by toxoplasmosis when the immune system is too weak to contain parasites in the cyst . Unlike pneumonia , pneumonitis usually affects larger areas of the lung.


The heart is also a muscle and may have cysts located in it. If the immune system is weakened, the parasite can cause cardiac inflammation, increasing the risks for the patient.


Chorioretinitis can affect immunocompetent people in the acute phase of toxoplasmosis, but it is rarely noticed because it tends to be discreet and pass quickly. However, in immunocompromised patients, this eye inflammation can become severe and lead to blindness in the affected eye. It is a more common problem in cases of congenital toxoplasmosis.

Toxoplasmosis in pregnancy

Toxoplasmosis is often a concern of pregnant women, since, although in most cases it does not affect the mother, the disease can cause serious problems for the baby and for the pregnancy.

The severity of the condition is different based on the stage of fetal development in which the disease is contracted. Since the cycle in which she is active lasts only a few weeks, it is at this point that there is concern.

One of the most important prenatal examinations is that of toxoplasmosis. It aims to find out if the mother has or has had the condition. If she has been infected with Toxoplasma gondii  in the past, the cysts may be present, but they are not a concern and there is no risk to the baby.

If the mother has never been infected, she must take precautions so that it does not happen during pregnancy. Avoiding contact with cats, for example, is important, in addition to making sure that the food is being well cooked to eliminate any chance of contamination.

The problem is that the mother is infected during  pregnancy. When toxoplasmosis enters its active phase during pregnancy, the baby can be infected through the placenta and that is where the danger lies.

The consequences of this infection depend on the time of pregnancy when it occurs.

First quarter

Interestingly, the earlier in the pregnancy the mother’s infection occurs, the less likely it is to pass to the fetus, but the greater the damage if it happens. The baby is rarely infected in the first trimester, but when it does, the damage is so devastating that most cases end up in miscarriage.

If there is no spontaneous abortion, the malformation of the fetus is possible and severe, and may result in a stillborn baby, which is when the birth takes place, but the child does not survive.

Second quarter

When the mother is infected in the second trimester, the chances of transmission to the fetus are greater, but the damage is reduced. The main organs affected are the eyes and the brain. The baby may have vision problems, seizures and malformation, which can also lead to the death of the fetus before birth.

Third quarter

When the mother contracts the disease in the third trimester of pregnancy, the chances of contamination of the fetus are considerably higher, but the damage is reduced. Malformations are minor, and may present only in adolescence in the form of seizures, attention problems, reduced vision, among others.

Should I stop living with cats during pregnancy?

Do not abandon your kitten. The pregnant woman does not need to stay away from him if he has had the disease before. If you have never been infected, it may be a good idea to stay away from the feline for those nine months. However, instead of giving up, donate the pussy or ask someone to take care of it during pregnancy. It is a more humane option.

How is toxoplasmosis diagnosed?

In the overwhelming majority of cases, toxoplasmosis does not even show symptoms, so it is difficult to know that the condition is present. Tests are usually performed on pregnant women to analyze the risks of pregnancy, but if there is suspicion, you can look for the parasite in any patient.

As the symptoms are not indicative of the disease, the easiest way to discover the protozoan is through a blood test.

The diagnosis is often made by the infectious disease physician  and, in some cases, by the ophthalmologist , as the only symptom that usually causes problems in immunocompetent patients is ocular.

Blood test (IgG and IgM)

The blood test for the diagnosis of toxoplasmosis does not seek to find protozoa. It examines the cells of the immune system.

When a microorganism infects us, the body produces two types of cells to fight this infection. The first is called Immunoglobulin M (IgM). It is a type of cell that begins the battle against microorganisms and is usually present in the acute stage of an infectious disease from the beginning.

When the blood test finds IgM cells, it is possible to know that the acute phase of an infectious disease is happening or has recently ended.

This blood test also looks for the second cell that the immune system creates, Immunoglobulin G (IgG). This cell also appears during the acute phase of the disease, but it is not an immediate response and only begins to be produced after a few days of infection.

Unlike IgM, IgG is specific for the microorganism in question. Our body has several different types of IgG, one for each type of infection that we have already faced and overcome.

IgG continues to be produced by the body in small doses and, if the same infection attacks us again, that production increases and we overcome the infection before it can do anything. This is how immunization is created.

When the blood test finds IgG cells specific for Toxoplasma gondii , but not IgM cells , it is possible to know that the patient has had the disease at some point in the past and is immune.


The same examination of the immune system is done in pregnant women. If IgG cells specific for Toxoplasma gondii are found , the woman is immune and does not have to worry about new protozoan infections.

If no IgG is found, she must take care and, when IgM cells are located, it is important to find out if the baby is infected for treatment to be carried out.

Fetal diagnosis

The fetal diagnosis can be made after the eighteenth week of gestation. It is done by puncturing amniotic fluid through a fine needle that crosses the placenta to collect the material.

This test is delicate and presents a small risk of miscarriage, but it is necessary to know whether the fetus is infected or not since the treatment is different when this happens.

Can Toxoplasmosis be cured?

-Yeah . Toxoplasmosis is curable. Treatment is only necessary when the patient is immunocompromised or pregnant, but it can be used even in immunocompetent people to accelerate recovery when the acute phase of the disease shows symptoms.

This treatment, by itself, does not cure the disease, only the acute phase. The protozoan cysts will remain dormant, contained in the patient’s tissues for a few years. These cysts can stay alive there for a long time, depending on the host species, but eventually they die and are eliminated from the body.

What is the treatment for toxoplasmosis?

Since the cysts are protected and well hidden, medications are not enough to eliminate them, but it is possible to speed up their containment process. Both immunocompromised people and immunocompetent patients can use specific drugs for the suppression of the protozoan.

Pregnant women can take another, less aggressive medication to contain the protozoan before it affects the baby, reducing the chances of damage from the infection.

If the baby’s diagnosis is positive, treatment should be done with potentially toxic and strong medications. The risk must be measured by the doctor.

Medicines for toxoplasmosis

The medications that can be used to treat symptomatic toxoplasmosis are:

  • Pirimetamina ( Daraprim );
  • Folic acid ( Endofolin );

Immunodepressed patients

Immunocompromised patients should take the same medications as described above, but until immunity is restored or the cysts are eliminated. In addition, to prevent serious infections in the lungs and brain caused by toxoplasmosis, another drug can be added.

  • Sulfametoxazol + Trimetoprima (Bactrim).


Infected pregnant women must take a specific antibiotic to deal with the protozoan, preventing damage to the fetus. Fetal diagnosis is still necessary.

  • Spiramycin ( Rovamycin ).


NEVER  self-medicate or stop using a medication without first consulting a doctor. Only he will be able to tell which medication, dosage and duration of treatment is the most suitable for his specific case. The information contained in this website is only intended to inform, not in any way intended to replace the guidance of a specialist or serve as a recommendation for any type of treatment. Always follow the instructions on the package insert and, if symptoms persist, seek medical or pharmaceutical advice.

Who has had toxoplasmosis is immune?

An important point to highlight is the fact that the majority of the population that has already been infected by the protozoan is immune to the disease. However, even with this in mind, the parasite remains in the individual’s body for some time, only inactive unless he acquires a disease that damages his immune system.

Living together

Usually, there is no difficulty in living with the disease. Most of the time it goes unnoticed and the patient never finds out that he has already had toxoplasmosis. Even when symptoms are present, they can be mistaken for flu and ignored.

In the case of immunodepressed patients, coexistence involves drug treatment for the elimination of the protozoan. Patients affected by congenital toxoplasmosis may need psychological, psychiatric, neurological, physical therapy, eye treatment and others, depending on the severity of the sequelae caused by the disease.


In immunocompetent patients, the acute phase of the disease passes within a few weeks. The parasite stays in the tissues, in cyst shape, for some time (it can vary from 1 to 5 years, depending on the species) until it is eliminated.

During this time, toxoplasmosis is latent and there are no symptoms or health consequences, as long as the immune system is not compromised. The patient becomes immune to new toxoplasmosis infections.

In the case of pregnant patients, treatment reduces the chances of contamination of the fetus by 60%. For the immunocompetent pregnant woman, there is the same prognosis as the patient with a functional immune system.

Immunodepressed patients, on the other hand, may have recurrences of the acute phase of the disease, just as they can be infected again. Medicines for toxoplasmosis should be taken until immunity is restored or the cysts are cleared by the body in a few years.

Complications of toxoplasmosis

The most serious consequences of toxoplasmosis are rare, but they do happen, especially in the case of immunosuppressed people or pregnant women. Are they:

Vision loss

Cysts can appear in the eyes, which can lead to loss of vision with the development of the protozoan. It is the most common complication among immunocompetent people since even in these people, the eyes are reasonably more sensitive to toxoplasmosis.

Vision loss is especially common in babies born with congenital toxoplasmosis.

Brain damage

When cysts located in the brain are not properly controlled by the immune system they can cause brain inflammation, which leads to damage to the central nervous system and other parts of the brain. This can cause motor and intellectual losses.

The patient may die as a result of this damage.

Heart problems

Like brain damage, cardiac damage can happen if cysts located in the heart’s muscles are not controlled. These damages can also lead to the death of the patient.

Pregnancy complications

The most famous complication of toxoplasmosis involves the contact of the protozoan with the fetus. Active disease can cause fetal malformation, spontaneous abortion, fetal death and other consequences.

How to prevent toxoplasmosis?

Toxoplasmosis is an infection so widespread that it is likely that you have already been infected and are even immunized. However, there are still people who have never had it before.

Especially in the case of pregnancy, after taking the exam and realizing that you have never had the disease, preventing it is very important. Check out the main actions you can take to prevent the disease:

Wash your food well

Vegetables as a whole should be washed well to avoid oocysts that may have been deposited on them while still on the plantation. Running water should be used for this cleaning.

Cook and roast the meat well

Undercooked and undercooked meat can contain protozoan cysts that are still alive, so they can infect someone. It is one of the most common ways of contamination by toxoplasmosis.

Avoid living with felines

If you are pregnant and have not been infected with the disease so far, avoiding cat places may be a good idea. Although the contamination with them only occurs through feces, it is possible that the environment where they sit is left with oocysts.

Wash your hands thoroughly

It is especially necessary to wash your hands well if avoiding living with cats is not possible, but it is also important even without living with cats. Washing your hands thoroughly ensures that contamination will not pass from them to your mouth, for example.

Common questions

Can dogs transmit toxoplasmosis?

Like any animal, dogs can contract the disease, but not spread it. Only felines can release the parasite’s oocysts through the faeces . As long as you don’t eat your dog’s meat, there is no reason to worry.

The same applies to any other animal. They can be contaminated, but not transmit the disease.

How do I know if my cat is infected?

Cats do not usually show symptoms of the contamination and the only way to know is to do the exams. Like humans, felines develop immunity to the disease after the first time they are contaminated and the cysts remain in tissues such as muscles, brain, heart, but without causing any damage.

Can I breastfeed with toxoplasmosis?

Toxoplasmosis is not transmitted through breastfeeding, so there is no risk of breastfeeding. If you contracted toxoplasmosis right after delivery, you need not worry, as the baby will not be contaminated through breast milk.

How to keep the cat healthy?

Try to keep the cat indoors! Home cats are much less likely to become infected, as they do not kill wild animals that may have the parasite, nor come in contact with feces from other cats that may have the disease.

A cat indoors also has the advantage of not getting involved in fights and getting other illnesses and injuries. Cats that go out on the street have a life expectancy of approximately 5 years while the most homely felines can reach up to 20!

Toxoplasmosis is a common disease that a large part of the population has already contracted and has become immune to. It can have serious consequences for immunocompromised people or pregnant women, but in general it is silent and does not cause problems. Share this text with your friends so they can learn more about it!