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Toxoplasmosis & Pregnancy - What You Should Know!

Many parents-to-be wonder whether they are putting their mother and unborn child at risk by keeping a cat.

Often people even consider whether to give up the cat during pregnancy. In the following, we will explain to you about toxoplasmosis and the risk of transmission through your own cat. The risk of being infected by your own cat is very low if the explained hygiene and precautionary measures are observed.

What is toxoplasmosis?

Toxoplasmosis is an infectious disease caused by the unicellular parasite Toxoplasma gondii. This is a so-called two host parasite. Cats are the ultimate hosts of the parasite, while other mammals and humans act as intermediate hosts.

Only cats excrete the so-called oocysts with their faeces, which can be ingested by the intermediate host (e.g. humans). In most cats, toxoplasmosis is asymptomatic. Around a quarter of the animals show mild diarrhea and only in rare cases do serious illnesses occur. Usually a cat sheds oocysts only once, namely after the initial infection. If the infection is re-infected, 90% of cats are immune, i.e. they no longer shed oocysts. In principle, however, re-elimination is possible in immunosuppressed cats.

How can humans become infected?

For humans, the main sources of infection are sporulated (infectious) oocysts from the feces of infected cats and, above all, cyst-infected, insufficiently cooked sheep and pork. Game meat can also be infected with T. gondii cysts. More recently, mussels have also been identified as a potential source of infection with the parasite.

Tissue cysts in meat remain infectious at refrigerator temperature (4 ° C). Freezing, salting, curing or smoking will kill most - but not all - of the cysts. When heated to at least 67 ° C for 20 minutes, the cysts will surely die. It is therefore important that pregnant women only eat sufficiently cooked meat. It must also be taken into account that not only raw meat is dangerous in itself, but that all objects and surfaces that come into contact with it are potential sources of danger.

T. gondii was found in the milk of some animals. However, acute toxoplasmosis in humans has only become known after consumption of fresh, unpasteurized goat milk.

Infection through contact with a cat that does not shed oocysts is not possible. Infection from petting infected cats is also unlikely. However, this transmission path cannot be completely ruled out.

Pregnant women and immunocompromised people should leave the cleaning of the litter box to someone else. Freshly excreted oocysts are not yet capable of infection and require 24 hours at room temperature for sporulation in the outside world - daily cleaning of the litter box prevents contact with infectious oocysts.

However, preventing contact with cats is not the same as preventing contact with T. gondii oocysts.

Dogs that ingest cat feces with sporulated oocysts also excrete a large part of them in an infectious state. Since such intestinal passers-by are usually excreted once with the faeces, a faecal examination is not useful. In addition, dogs that wallow in cat feces containing infectious oocysts can introduce the oocysts into the home.

Other possible sources of sporulated oocysts are contaminated soil, dust (inhalation of oocysts after dust is raised by horses in riding stables is described), and contaminated drinking water.

The consumption of unwashed, raw vegetables and fruits can theoretically lead to a toxoplasmosis infection.

How does an infection with Toxoplasma gondii show up?

After ingestion of the Toxoplasma oocysts, they can settle in the muscles and internal organs in humans and form tissue cysts there. In most people, the infection runs without symptoms or with only mild, unspecific symptoms such as fever, tiredness, fatigue, flu-like symptoms, headache, muscle aches and pains, swelling of the lymph nodes and occasionally diarrhea. Inflammation of the nerves and brain can occur in children, the elderly or people with weakened immune systems. In pregnant women, an infection with T. gondii can lead to various complications, depending on the time of infection and the stage of pregnancy (see below). After surviving an infection, the body has formed antibodies and is thus protected against renewed infection. Pregnant women can have this antibody titer determined. If a titer is available, there is no risk of toxoplasmosis infection. About 60% of women who become infected with T. gondii during pregnancy will transmit the parasite to the unborn child. The time of the fetus infection is decisive for the severity of a later illness. If an infection with T. gondii occurs in the first 10 weeks of pregnancy, it is rarely transmitted to the fetus, but in these cases an abortion or a serious illness of the child is to be expected. Pregnant women are at greatest risk of giving birth to a severely infected child if they are between 10 and 24 years of age. Week of pregnancy. In the case of an infection between the ages of 26 and 40 At the 1st week of pregnancy, the child is likely to be infected, but with mild symptoms.

How can you tell if a cat is shedding Toxoplasma gondii oocysts?

There are several tests that can be used to determine if a cat sheds T. gondii oocysts.

A fecal examination can determine whether the cat is shedding oocysts. The best way to do this is to examine collected feces (over 3 days) parasitologically. In addition, it can be determined in the blood whether a cat has antibodies against T. gondii and has therefore already dealt with the pathogen. If the antibody titer is positive, a titer determination should be carried out again after 2 weeks. In this way you can determine whether the infection is acute or chronic.

An acute infection can be treated. In the case of a chronic infection without the simultaneous excretion of oocysts in the feces, the risk of infection by the cat is very low.

How can you protect yourself from infection with Toxoplasma gondii?

Some precautionary measures should be observed during pregnancy in order to minimize the risk of infection (with T. gondii or other pathogens):

  1. Have the antibody titre determined to see whether there is any risk of infection.
  2. No consumption of raw meat or unpasteurized goat milk (raw milk cheese!).
  3. When cooking, make sure that objects that have come into contact with raw meat do not come into contact with other foods and that everything is carefully cleaned (dishwasher, boiling water).
  4. Wash hands carefully after contact with raw meat.
  5. Have someone else clean the litter box every day, if possible.
  6. Have your own cat examined: Collective faeces sample: Parasitology Blood sample: Antibody titers (IgG and IgM).
  7. Dog owners should make sure that their dog does not eat or wallow in cat poop.

As already mentioned, the oocysts need 24 hours to sporulate, i.e. to become infectious. If a pregnant woman does not clean the litter box herself and the cat feces are removed once a day, the risk of a toxoplasmosis infection is limited even in a cat that excretes oocysts.

How high is the risk of contracting toxoplasmosis during pregnancy?

The following statistical overview is intended to give an overview of the actual occurrence of infections with T. gondii.

Congenital toxoplasmosis in Germany according to estimates by the "Toxoplasmosis and Pregnancy" commission of the former Federal Health Office (BGA):

  • Number of births per year: 880,000
  • Mothers with specific antibody titer: 440,000
  • Number of high-risk pregnancies: 440,000 (50%)
  • Number of pregnant women with antibody production during pregnancy: 4,400
  • Number of infected newborns: 2,200 (equivalent to 0.25%)