Toxoplasma gondii is a single-celled animal that is found world-wide as a parasite of cats, other animals and birds, from whom it may spread to humans. The eggs pass out in the faeces of the animal and may then enter a human mouth (eg. after careless handling of cat litters or soil contamination of fingers or food). Undercooked meat that has been contaminated may also be a source. Once in the gut, the microscopic egg hatches and multiplies into millions of single-celled animals.
In many patients, the symptoms are so mild that they are ignored, but in severe cases the patient complains of a low-grade fever, tiredness, muscle aches, joint pains, headache, sore throat, a mild rash and enlarged glands. In the rare severe cases, the liver, spleen, lungs, eye, heart and brain may be involved.
Patients usually recover without treatment in four to eight weeks. If symptoms are significant or complications develop, medications are available (e.g. pyrimethamine) to destroy the infection.
The worst complication of toxoplasmosis occurs in women who are pregnant. The infection may cause miscarriages, still birth, and deformities in the baby (eg. small head, hydrocephalus, mental retardation, fits, blindness). The disease can be detected by a specific immunoglobulin blood test, and this test is often routinely performed during antenatal blood examinations. If toxoplasmosis is detected in pregnancy, treatment will be given to cure the disease. Unfortunately, because the disease has already occurred, there may still be some damage to the foetus.
There is no vaccination or other form of prevention available. Pregnant women should not associate closely with cats.