Hygienic requirements for pregnant women to protect against food infections - Part III


Hygienic requirements for pregnant women to protect against food infections - Part III

Extra information on Toxoplasmosis

In addition to sources of infection via food with tissue cysts of toxoplasma via:

  • raw or underheated meat or perhaps fish* - raw sausages are also included

*(fish rarely transmit toxoplasmas, but they transmit listeria)

  • or things* that had contact with raw meat *(vegetables, fruit, crockery, cutlery, work surfaces)


Caution is also required when contacting cat feces and their food.

  • it is best to always use single-use rubber gloves (however, it is best not to do this work for pregnant women)
  • always wash hands well with soap and disinfect if necessary (see above)
  • work with gloves when gardening
  • also, wash your hands particularly well after playing with children in the sandbox
  • the same applies in the horse stable because there can be toxoplasma oocytes
  • this is also on farms – wherever there are more cats.

Dogs can absorb toxoplasma cysts via raw meat (possibly sickening themselves), but they are not end-hosts, which means, they do not excrete them via the feces; they are not infectious.

In the case of a future planned pregnancy, it is important to examine the toxoplasmosis antibody titer before pregnancy. If there is a positive antibody titer before fertilization, there is no risk of the transmission of toxoplasmas to the fetus. It is assumed that only the first infections of the mother during pregnancy (means previously seronegative antibody titer) pose a risk of transmission to the child.

If there are no antibodies against toxoplasmosis, pregnant must even prevent more cautiously and carry out several checks during pregnancy. The greatest risk of infection of the mother and transmission to the fetus is between the 10th-20th week of pregnancy and much more during the childbirth

With infection in the early weeks of pregnancy, transmission to the fetus is low (approximately 1-2%) however, high risks result in serious damage, often also aborting; in the case of infection of the child during the birth process, which very often leads to transmission (80%) to the child, when the mother is not previously treated. Then the damage is mostly less and often even symptomless, but new problems can still occur after years – e.g. brain and eye damage (further information will follow extra).

The safest way is to be careful and minimize the risk of infection. In the case of seronegativity (absence of anti-bodies), the hygiene measures regarding the sources of infection must be strictly observed and the pregnant woman should be examined for toxoplasma several times throughout pregnancy. In the case of initial infection in pregnancy, both serological and sonographic follow-up controls are strictly necessary and depend on the time of infection and symptoms, different antibiotic therapy regimens, as well as folinic acid (the (5-formyl tetrahydrofolate not the folic acid as the synthetic form of folate) supplementation in the pregnant woman and, if necessary, also in newborns, are necessary. Only the uncomplicated, postnatal acquired toxoplasmosis requires monitoring and no therapy of the child.

Summary of infection protection in the context of nutrition

Pregnant women should not consume raw food from animals! 

In our cultural areas, this mainly concerns products made from raw milk, or raw meat (e.g. various sausages and little cooked steak, etc.) or raw fish or raw marine animals (sushi and smoked or stained fish products). Some other foods that have a higher possibility of contamination should also be avoided.

Some more information on salmonellosis, toxoplasmosis, and listeriosis (context pregnancy) based on data from the Robert Koch Institute (RKI)


According to data from the Robert Koch Institute, there have been between 300 and 600 listerias infections per year in Germany in recent decades(10% of which affects pregnant women or their newborns).

Listeriosis is in principle a food-based infectious disease. In addition to a variety of animal foods such as meat or meat products (e.g. sausages), as well as fish and fish products (mainly smoked fish), milk and dairy products (especially cheese), listeria is often also found on plant foods, e.g. pre-cut salads.

Foodstuffs, in particular vacuum-packed foods, should be consumed as quickly as possible after purchase and well before the stated minimum shelf life has expired. Vacuum packaging and refrigerator storage do not protect against listeria from propagation, as with other food infectious germs. On the contrary, with long storage periods, this can lead to a selective increase in listeria.

These foods may be contaminated with listeria, for example, during milking, slaughter, or contamination over the environment. In addition, the processing and treatment of contaminated raw materials do not always lead to the complete killing of the bacteria, for example in the case of raw milk soft cheese, raw sausage, or minced meat. 

 However, contamination could also happen in the food processing industry, as well as when working with plants where hygiene standards have been handled carelessly.

In the listeriosis of a pregnant woman or her child, the infection occurs during pregnancy (transplacental), during childbirth when passing through the birth canal or postnatal through contact between mother and infant.

In immunocompetent people, infection is rare, and even less common you get a disease, and if, it often occurs only as a mild, uncharacteristic feverish reaction. Recent studies have shown that after eating contaminated foods, severe, feverish, self-limiting gastroenteritis can occur even in healthy people within a few hours up to 2 days.

The risk of manifest disease is mainly for people with reduced defenses such as newborns, the elderly, patients with chronic diseases (e.g. tumors, AIDS) or glucocorticoid therapy, transplanted, and pregnant women. Manifest listeriosis manifests with flu-like symptoms such as fever, muscle pain as well as vomiting and diarrhea. Sepsis can also occur in complicated cases. 

As antibiotic drugs of the first choice, amoxicillin or ampicillin are considered high-dose, combined with an aminoglycoside, unless this is contraindicated, e.g. due to pregnancy.


Salmonella infections were around 15,732 reported cases in 2018, the absolute majority of which affected young children. For pregnant women, the cases are not recorded, as they usually only produce diarrhea, after which no salmonella tests are carried out.

In Germany, salmonellosis is also rarer compared to other countries. Typically, salmonellosis occurs more often in late summer. Children under the age of 10 are most likely to be affected (especially young children).

Frequent sources of infection for salmonella are through contact with raw meat (often poultry) and raw milk or raw eggs, but infections via contaminated chocolate or even herbal teas were seen in Germany.

The Robert Koch Institute also recommends that reptiles should not be kept in households with children under 2 years of age.

The infection dose for the adult is 104-106 germs. If salmonella is present in highly fatty foods (e.g. cheese, chocolate, salami), in spices, or if there is a special disposition, e.g. weak resistance, as in infants, young children, the elderly, diseases have already been observed in infection doses under 102 germs.

Salmonellosis usually manifests itself as acute intestinal inflammation with sudden diarrhea, headache and abdominal pain, discomfort, and sometimes vomiting. Frequently, mild fever occurs. Symptoms often persist for several days. In young children or older adults, the resulting dehydration can be pronounced. In rare cases, the initial intestinal inflammation can take a septic course with a partly high fever.

The infestation of other organs is possible, but very rare (again, mainly elderly and defense-weakened persons are affected).

In the gastroenteritis course, no antibiotic therapy takes place, as this can prolong bacterial elimination. Normally, it is only necessary to compensate for the loss of liquid and electrolyte. Antimicrobial therapy is indicated for severe forms of course in the sense of systemic inflammatory response syndrome (SIRS) or sepsis. Due to possible complications that cannot be excluded, antimicrobial therapy should be considered for diseases in the 1st year of life, in the elderly, persons with congenital or acquired immunodeficiencies, and patients with known abnormalities in the heart valves or vessels.


Since toxoplasmosis is most commonly compared to the others mentioned, it is important to have more information.

Toxoplasmosis infections are absolutely more common (about 30% of the world's population is infected), but only about 1% of pregnant women in Germany (pregnant women who had not previously formed antibodies and were probably infected only during pregnancy) transferred the toxoplasmas to the fetus. In a study period between 2008-2011, researchers identified 345 newborns with clinical symptoms each year (at an assumed rate of 27% symptom formation).

If pork, beef, sheep, or poultry meat is not sufficiently cooked or even eaten raw (e.g. raw sausage, minced meat, tartar), tissue cysts of toxoplasmosis (a permanent form of the parasite) in this meat can survive and lead to infection.

In most cases, the infection proceeds without problems or even without symptoms and people then form antibodies against the toxoplasmas for lifelong. Younger people are more often than older people still seronegative – that means they are still without antibodies, as the sources of infection add up over the course of life. In Germany, 20% were found to be infected in young adults (18-29 years old) and 76.8% in seniors (70-79 years old). 

Pregnant women who have not yet developed antibodies against Toxoplasmagondii and become infected during pregnancy may transmit the pathogen to the unborn child. Depending on the time of infection, this can lead to severe permanent neurological damage up to severe visual impairments. The same applies to people with a severely impaired immune system.

Symptoms of infection include fever, headache, and muscle pain. In healthy (immunocompetent) people, however, the infection usually proceeds without symptoms.

The majority of initial infections are self-limiting, and there are well-received drugs for acute infection (but not for the persistent ones). Acute Toxoplasma infection is transferred to a chronic latent form, toxoplasma cysts persist in the tissue symptomless for a lifetime.

The effectiveness of various materno-fetal therapy regimens (antibiotic combinations)in initial infection in pregnancy is still controversial. There are different regimens of therapy depending on the time of infection – that means, the week of pregnancy of the infection.

See "RKI-Ratgeber

Scientific Reports vom 3.3.2016: Hendrik Wilking, Michael Thamm, Klaus Stark, Toni Aebischer & Frank Seeber: Prevalence, incidence estimations, and risk factors of Toxoplasma gondii infection in Germany: a representative, cross sectional, serological study

and RKI Guide

Prof. Dr. Werner Seebauer is Dean of Studies – Association of German Preventologists, Head of Preventive Medicine Department of Institute of Transcultural Health Sciences (European University Viadrina) and Head of Preventive Medicine – NESA (The New European Surgical Academy). Since 2000, prof. dr. Werner Seebauer worked only in preventive medicine, after ten years spent at the Frankfurt University Hospital. He is also involved in the medical professionals training for nutrition and prevention.