Toxoplasmosis is caused by the single-celled parasite Toxoplasma (T.) gondii. In the case of an initial infection during pregnancy, the pathogens can be transmitted to the unborn child (connatal infection) and cause severe damage to or death of the unborn child. About half of all toxoplasmosis infections are said to be food-borne.
Infections with T. gondii are common in animals and humans worldwide.
Cats and other felids are the final hosts, in which the sexual reproduction of the parasites can take place. If cats feed on rodents or birds that contain toxoplasma cysts in their tissues, or if they are fed raw meat that contains toxoplasma cysts, the parasites undergo a sexual reproduction cycle and are excreted as oocysts in the faeces.
The range of possible intermediate hosts that can become infected by oocysts includes humans, sheep, goats, rodents, pigs, cattle, chickens and birds.
Mode of transmission
Intermediate hosts, including humans, acquire infection by oral ingestion of oocysts during contact with infected cats, by ingestion of food contaminated with cat faeces, or by oral ingestion of permanent forms (Toxoplasma cysts) in the tissues of an intermediate host (e.g. undercooked sheep meat). If a first-time infection with parasitemia (appearance of parasites in the blood) occurs during pregnancy, toxoplasma can also be transmitted diaplacentally to the unborn child via the blood route.
10-23 days after consumption of cysts in raw meat or 5-20 days after ingestion of oocysts (e.g. through vegetables contaminated with cat faeces).
In healthy adults, infection with T. gondii usually progresses without signs of illness or with unspecific symptoms. In most cases, infections in the first trimester of pregnancy results in the death of the fetus. In the second trimester, hydrocephalus, calcifications in the brain or severe eye damage may occur. In the last trimester, infection usually leads to clinically inconspicuous newborns; late damage can only occur months or years later, in the form of developmental disorders, mental retardation or eye changes, even blindness. In immunocompromised persons (e.g. AIDS), infection can lead to unchecked multiplication of the toxoplasma cysts, with the development of brain toxoplasmosis in the form of encephalitis.
Treatment of existing symptoms with medication.
Pregnant women who have tested negative for antibodies against toxooplasmosis should avoid contact with new cats (cats that have not been living in the household for a long time and cats whose eating habits cannot be controlled), as well as avoiding undercooked meat and washing vegetables thoroughly before consumption. Wear work gloves when gardening because of the possibility of contact with cat feces.