Toxoplasma gondii, a unicellular parasite, triggers one of the most common infectious diseases: toxoplasmosis. It infests birds and mammals – and therefore also humans. For a long time, the first infection was especially for pregnant women as particularly dangerous because the pathogens pass on to the fetus and can lead to damage to miscarriage. Researchers have now been able to prove that the parasite can also have a negative effect on signal processing in the brain.

Risk not only for pregnant women

Scientists from the Institute for Inflammation and Neurodegeneration of the Otto von Guericke University (OvGU) Magdeburg and the Leibniz Institute of Neurobiology (LIN) – also in Magdeburg – could prove in a study that the unicellular parasite the molecular composition of synapses in the Brain changes.

Toxoplasma gondii is absorbed by humans via digestion, enters the bloodstream and also migrates to the brain, where it lingers for life in nerve cells.

Dr. Karl-Heinz Smalla, LIN

In previous animal experiments, the researchers from Magdeburg were able to prove that there were strong behavioral changes in infected mice. For example, mice showed significantly less anxiety after toxoplasmosis-for example, in cats. In order to find an explanation, synapses in mouse brains were examined more closely. They are responsible for the transmission of signals from nerve cell to nerve cell.

More often than thought

It is estimated that 30 to 50 percent of people experience exposure to toxoplasma during their lifetime. Often, those affected do not notice, because the infection is usually rather inconspicuous. Short-term cold symptoms such as chills, fever and body aches can be the result, says Ildiko Rita Dunay, who heads the Institute of Inflammation and Neurodegeneration at OvGU. For pregnant women or people with weakened immune systems, however, such an infection can be dangerous.

There is no therapy to get rid of the parasite when it attacks the brain. So once you're infected, it will last a lifetime.

Prof. Dr. Ildiko Rita Dunay, OvGU

Conjectures now suggest that a toxoplasmosis infection in the brain could even be a risk factor for neuropsychological disorders such as depression, schizophrenia or autism.

Protection against infection

The most common source of transmission is cat feces, because cats are particularly often infected with toxoplasma. Even cleaning the cat toilet can be enough.

Also, meat that has not been heated enough, the parasite can enter the body, so it should always be cooked well. Raw fruits or vegetables should always be washed thoroughly. In moist soil, toxoplasts survive for several months. Therefore, one can also become infected with the pathogen during gardening.


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