Toxoplasmosis in pregnancy – causes, symptoms, treatment and prevention. What effect does this disease have on the fetus?

Toxoplasmosis is divided into acquired and congenital, depending on the type of infection. The disease can take a variety of forms, so the mother-to-be should be extra careful when eating or caring for her cat. It is also worthwhile to perform preventive tests, which are usually ordered during the first trimester of pregnancy. In the event of infection, contact your health care provider immediately.

Toxoplasmosis – what is the disease?

Toxoplasmosis is a parasitic disease caused by a protozoan called Toxoplasma gondii. The first human infections with this parasite were detected in 1937, a dozen years after its discovery. The patients were then diagnosed with congenital toxoplasmosis, acquired while still in fetal life. At the time, the causes of the infection were not well understood. Nothing was also known about the parasite’s development cycle. These features were discovered many years later after the first cases of disease. The residing parasite is present in cat feces, in dirty and unpeeled fruits and vegetables or raw meat. It can be infected for up to 5 days after direct contact.

In Poland, only a small percentage of pregnant women struggle with toxoplasmosis. Most of them have had the disease in the past, as shown by the presence of antibodies in the blood. However, most cases of the disease are reported in Asia and northern Europe, which is why screening is so common in these regions.

How can you contract toxoplasmosis during pregnancy?

Toxoplasmosis is transmitted mainly by cats, specifically their feces. However, this is not the only route of infection. Three of them are distinguished. The most common is the gastrointestinal route. Penetration of the parasite oocysts into the body occurs as a result of eating raw or insufficiently cooked meat or raw and unwashed fruit. Drinking untreated water, especially from contaminated soil, also carries the risk of contracting the disease. It is through the digestive route that cats become infected. Contact with cat feces also exposes us to infection.

Another pathway is transplacental disease. It happens when a pregnant woman struggles with active toxoplasmosis and passes the disease to her yet unborn child. Infection is also possible during transfusion of infected blood and organ transplantation, but such situations are rare.

Congenital and acquired toxoplasmosis

Toxoplasmosis is divided into congenital and acquired. The congenital form is one that is diagnosed shortly after birth. It is transmitted during fetal life through the mother’s placenta and is very dangerous to the child who has not yet been born.

The acquired form, on the other hand, is an infection acquired through the oral route or as a result of direct contact with cat feces. The infection is asymptomatic at first, but once the disease develops, it can take a different course. For this reason, it is divided into different forms:

• eye disease, progressing with retinitis pigmentosa and deterioration of visual acuity,
• cerebral, with encephalitis or meningitis,
• nodal, which manifests itself as significant enlargement of lymph nodes, fever, muscle aches and poor general well-being.

Acquired toxoplasmosis can also have a generalized form, which usually accompanies people with declines in immunity or diseases of the immune system. In such patients, the protozoan not infrequently leads to changes in the lungs or heart.

How does toxoplasmosis manifest itself in pregnancy?

A woman may not know about toxoplasmosis infection during pregnancy at all, as the disease usually produces no symptoms. Whether they appear later depends on the patient’s immune system, her age and other ailments. The risk of any symptoms increases the older a woman is, and her immune system is very weakened.

Symptoms of infection usually occur in about 10% of infected women. Symptoms are then similar to those that accompany mononucleosis – an infectious, flu-like disease. Although it is caused by EBV infection, it produces almost identical symptoms to the protozoan parasite that settles in the body. These include enlarged lymph nodes, muscle pain and headaches, as well as increased fatigue and sweating. A pregnant woman may complain of a bad general feeling, weakness and struggle with fever. Worrying symptoms should be reported immediately to the doctor in charge of the pregnancy so that he has a chance to order the necessary tests as soon as possible.

What is the risk of infection to the fetus? Congenital toxoplasmosis

The unborn child can only contract toxoplasmosis during active infection in the mother, several weeks shortly after the mother’s infection begins. It does not matter whether it is asymptomatic or manifests itself with specific symptoms. The risk of transmission varies between 30 and 40%, and depends on the duration of the pregnancy. The later the trimester, the faster the fetus can become infected. The least risk of fetal infection is during the first trimester of pregnancy, but the consequences for the developing baby in the womb are the most serious.  In the third trimester, the possibility of transmission to the fetus is much higher than in early pregnancy.

The consequences of infection are unpredictable. The parasite’s actions can lead to intrauterine death of the fetus, its malformations or severe neurological disorders, such as microcephaly, hydrocephalus or encephalopathy. The child is also at risk of retinitis pigmentosa and cerebral calcification. After birth, they can  result in seizures and visual disturbances. Such severe complications are possible if the infection occurs at a very early stage of pregnancy. Fortunately, such infections are rare.

Most infections are encountered in the final trimesters of pregnancy. They are dangerous because no alarming symptoms are seen in the baby after birth, but the baby may have an enlarged spleen, liver and pneumonia. Some infections also manifest themselves in jaundice, and in later stages in visual disturbances and neurological changes. If, after testing, it turns out to be the result of toxoplasmosis infection, the child should remain under the care of specialists for the next two years of life.

Testing for toxoplasmosis in pregnancy

The basis for diagnosing or ruling out toxoplasmosis is a serological test for IgG and IgM antibodies. They are first performed in early pregnancy, before the 10th. of the week. A negative result indicates health, but the test should be repeated prophylactically once every trimester or as recommended by the doctor. The presence of IgG antibodies, with no IgM antibodies, suggests that the woman has survived toxoplasmosis and acquired immunity. The risk of transmission of the parasite to the fetus is impossible in this situation.

Toxoplasmosis results in pregnancy are difficult to interpret, so it is better to have them evaluated by a specialist. It reads as follows:

• Negative IgG and IgM indicates that the woman has never undergone Toxoplasma gondi infection. Therefore, there is no immunity to the disease.
• Negative IgM, positive IgG (but not too high) indicates a history of toxoplasmosis and the possession of specific immune antibodies.
• Positive IgG (especially high), negative IgM is a sign that a woman has undergone a recent infection, so she should make sure that the parasite does not continue to wreak havoc on her body. The test is repeated after several weeks with an additional determination of antibody avidity. The pregnant woman requires treatment if the test comes out positive again.
• Positive IgM, negative IgG indicates an ongoing infection. In order to avoid passing the disease to your child, immediate further testing and treatment is essential.

The purpose of preventive testing is to catch the moment of toxoplasmosis, which is why it is so important. With the test and the ability to quickly implement treatment, the complications that threaten when the fetus becomes infected can be prevented.

Read also: What is an ultrasound examination?

Toxoplasmosis – treatment during pregnancy

Treatment of toxoplasmosis in pregnancy is not easy, but is necessary to prevent transmission of the infection to the fetus. For this purpose, the pregnant woman is given spiramycin, a macrolide antibiotic. The substance is one of the few that is safe for the unborn and developing baby. However, it only works if there has been no transmission of infection. Diagnosis of fetal morbidity during ultrasound is associated with a change in medication. In this case, spiramycin is replaced by pyrimethamine and folinic acid, which cross the placenta.

How can toxoplasmosis be prevented in pregnancy? Preventive measures

To prevent toxoplasmosis infection during pregnancy, it is essential to follow several rules:

• Clean the cat’s litter box with gloves, preferably several times a day,
• Do not take home new animals or interact with feral cats,
• Thoroughly wash and peel vegetables and fruits,
• Do not eat raw or undercooked meat,
• Do not drink water from unknown sources,
• utensils and cutlery that have been in contact with raw vegetables, fruits or meat should be washed in warm soapy water after each use,
• protect themselves with gloves when working in the garden, as well as contact with the ground.

The most important measure is regular serological testing, which every pregnant woman should undergo. They are more often carried out in women who have not previously been ill and do not have antibodies in the body. They should do the test every trimester of pregnancy to keep an eye on the timing of the disease.