Especially dangerous during pregnancy

Quick Reference: Toxoplasmosis

What is toxoplasmosis? Toxoplasmosis is an infectious disease caused by the unicellular parasite Toxoplasma gondii. Infections with the pathogen are common, but mostly harmless. Toxoplasmosis is dangerous during pregnancy and for people with a weak immune system.

Symptoms: Toxoplasmosis is usually accompanied by mild symptoms such as fever, headache and chills. During pregnancy, toxoplasmosis can cause lasting damage to the unborn child and cause a miscarriage. Immunocompromised people are at risk of encephalitis.

Infection: Often through undercooked meat, ground pork or food that grows close to the ground, contact with cats and cat faeces, gardening, via the placenta in the womb

Is toxoplasmosis notifiable? There is only an obligation to report the infection for congenital infections, but not for infections that occur in the course of life.

How common is toxoplasmosis? Toxoplasmosis is widespread and occurs in all regions of the world. About 50 percent of adults in Germany are or have been infected with the pathogens (seroprevalence). The infection rate increases with age and reaches more than 70 percent in the over 70-year-olds.

At a glance:

What is toxoplasmosis and how is it transmitted?

Toxoplasmosis is an infectious disease caused by the unicellular parasite Toxoplasma gondii. The infectious disease is one of the zoonoses. These are diseases that can be transmitted between animals and humans. Toxoplasma have a complicated life cycle with host switching. Cats are the definitive host and therefore the main carriers. They excrete infectious pre-stages (oocysts) of the parasite, which other animals ingest through contaminated food. The parasite multiplies in the so-called intermediate host and forms cysts in the muscle tissue, which are also contagious when the meat is eaten. Mammals, birds and humans are usually only intermediate hosts.

routes of transmission to humans

Infection is transmitted to humans via two main routes:

1. Eating raw or undercooked meat
2. Dirt and smear infections caused, for example, by gardening or contact with cats or their excrements

The risk of infection is particularly high for people who eat raw or undercooked meat and meat products. Common sources of Toxoplasma gondii are pork, mutton and goat meat, as well as game and poultry. Other possible routes of infection are through smear infections with insufficiently washed raw vegetables and lettuce and fruits that grow near the ground, such as strawberries. The parasites can survive for a long time, especially in moist soil. Therefore, for example, infection with gardening with toxoplasmosis is possible.

Toxoplasma can also be found in the feces of cats newly infected with toxoplasmosis. Under favorable conditions, the parasite can survive for a few months, making it a possible transmission route for humans. If dogs eat cat feces that contain Toxoplasma gondii, they too can transmit the parasite to humans. The parasite can also be transmitted during an organ transplant.

Toxoplasmosis: what symptoms does the infectious disease cause?

After an incubation period of about two to three weeks, the parasite Toxoplasma gondii infects cells everywhere in the human body and causes inflammation. The disease usually runs its course in healthy people with no or only weakly pronounced symptoms. If there are complaints, they usually cannot be clearly assigned. Flu-like symptoms often occur with:

Therefore, the infection with toxoplasmosis is often not noticed as such by those affected. Only in rare cases does the pathogen also affect the eyes or other organs such as the lungs or the brain. This leads to inflammation of the respective organ, which can lead to serious complications.

People with a weakened immune system, such as patients infected with HIV, are particularly at risk of a severe and complicated course of the disease. Here the infection manifests itself as a severe feeling of illness with a very high fever. If the brain becomes inflamed (encephalitis), other symptoms also appear. Depending on which region of the brain is affected, it comes to about:

• Headache
• changed traits
• paralysis

Toxoplasmosis in pregnancy

In rare cases, transmission occurs through the placenta during pregnancy from the infected mother to the unborn child. This usually only happens with primary infections during pregnancy. The later in pregnancy the infection occurs, the greater the risk of fetal transmission. Depending on the stage of pregnancy, damage to the central nervous system (CNS) or organs (e.g. the eyes) in the unborn child is possible.

If the infection occurs in the first trimester of pregnancy, the risk of a miscarriage or stillbirth is particularly high. If, on the other hand, an infection with toxoplasmosis occurs in the second or third trimester of pregnancy, it is usually asymptomatic. Only later in life do the affected children suffer from long-term effects such as epilepsy, strabismus or deafness.

On the other hand, if the expectant mother was already infected with toxoplasmosis before the pregnancy, there is little danger for the child. In this case, the mother’s antibodies are also passed on to the unborn child and protect it from infection with toxoplasmosis.

Diagnosis of toxoplasmosis: test for antibodies

Toxoplasmosis is diagnosed by a blood test. As part of a test, antibodies against the causative parasite Toxoplasma gondii are detected in the blood. If certain antibodies (IgG and IgM) are found in the blood sample, an infection with toxoplasmosis is considered certain. Whether it is a recent or past infection can be determined from the type and amount of antibodies.

Although a test for toxoplasmosis is only carried out if an infection is suspected, women who want to have children or are in the early phase of pregnancy should be examined in order to avoid infection and possible consequential damage to their unborn child.

Direct detection of toxoplasmosis

Direct pathogen detection is often carried out in people with a weakened immune system. For this purpose, tissue samples or body fluids are examined for the parasites themselves or DNA from Toxoplasma gondii. If infection is suspected during pregnancy, the amniotic fluid or umbilical cord blood can be tested to check for toxoplasmosis infection in the fetus.

How is toxoplasmosis treated?

With a healthy immune system, the body can usually fight off the infection itself, especially since the initial infection with Toxoplasma gondii is often not even noticed. If, on the other hand, severe symptoms appear, medication is used. Therapy is also carried out in people with a weakened immune system and in toxoplasmosis during pregnancy and in newborns.

All drugs that are used for treatment inhibit certain metabolic processes (folic acid and protein synthesis) of the toxoplasmosis pathogen. Doctors use certain antibiotics and antiparasitics. Possible active ingredients are:

• Spiramycin
• Pyrimethamine
• Sulfadiazine
• Clindamycin
• Atovaquone

The treatment usually lasts four weeks.

Therapy for toxoplasmosis in pregnancy

If an initial infection with toxoplasmosis occurs during pregnancy, treatment is imperative. Some of the active ingredients against toxoplasmosis act as folic acid antagonists in the body. Folic acid is very important during pregnancy, as a deficiency endangers the healthy development of the fetus. Most women therefore take folic acid as a dietary supplement. If appropriate medication is used, supplementation with folic acid should be replaced with folinic acid. Otherwise the success of the therapy is at risk.

Course of an infection with toxoplasmosis

Toxoplasmosis is usually harmless. Only the swollen lymph nodes can persist for several weeks after the infection has healed. After the initial infection with toxoplasmosis, there is lifelong immunity.

In the case of an immune deficiency, the prognosis depends on the severity of the infection and the general condition.

How to prevent toxoplasmosis

Infection with Toxoplasma gondii cannot be reliably prevented. However, compliance with certain rules of hygiene and conduct significantly reduces the risk.

Avoid typical risk factors for toxoplasmosis:

• Do not eat raw or undercooked meat

• Wash or peel raw fruit and vegetables before eating

• Rinse kitchen utensils and cutting boards thoroughly after use

• Wash hands before eating

• Wear gloves when gardening

• Wash hands after gardening or visiting sand playgrounds

• keep away from cat feces; pregnant women in particular should pay attention to this

• Pregnant women and people with a weakened immune system should not pet free-roaming cats

If a cat is kept in the home near the pregnant woman, it should be fed canned and/or dry food and not raw meat. Regular cleaning of the litter box with hot water is recommended. Cleaning the litter box should be avoided during pregnancy. If this is not possible, it is advisable to wear gloves. Since transmission through dust cannot be ruled out, wearing a mask can also be recommended.