Toxoplasma gondii is an obligate intracellular parasite which belongs to the class Coccidia. It is ubiquitous and causes clinical signs in all warm-blooded animals, including humans.
More than 1 billion people worldwide have antibodies against toxoplasma. In addition to fever and cold-like symptoms, congenital infection during pregnancy is feared. The intrauterine infection of the foetus occurs approximately 3 – 4 weeks after the first infection of a seronegative mother, when the placental barrier is crossed and placentitis occurs. Miscarriages and severe neurological or ophthalmological diseases can occur in the newborn. The cat as the definitive host excretes oocysts for approx. 3 weeks, which sporulate and become infectious after approx. 2 – 4 days, depending on temperature (daily cleaning of the cat litter box!).
Another source of infection is meat contaminated with tissue cysts that has not been sufficiently cooked before consumption. However, the main source of infection is gardening, where oocysts may be absorbed via contaminated soil (aerosols).
Cats can also be intermediate hosts at the same time; they rarely fall ill, but the clinical signs depend on where the tissue cysts are located. For example, hepatitis, cholangitis, dyspnoea may occur, and in case of CNS involvement, there may be ataxia, motor deficits and epileptic seizures. Additionally, uveitis and chorioretinitis can occur. The same signs can also be seen in dogs.
In sheep and goats, about 10% of the abortions worldwide are attributed to T. gondii.
In Germany, the authorities must be notified if Toxoplasma gondii is detected in cats, hares, rabbits, equids, ruminants, pigs and other mammals, especially those supplying food.