Toxoplasmosis (Toxoplasma gondii) is a parasite that lives within cells of animals. It reproduces in the cat but may also exist in humans and can be found in beef, lamb, chicken and pork. The main ways that humans can acquire toxoplasmosis is from cat urine and faeces (often by gardening or by exposure to litter trays), and by eating infected meat.
In Europe, 50% of pregnant women have previously been infected by toxoplasmosis and so are immune to this infection in the future. The remaining 50% do not possess protective antibodies and so are susceptible to infection. Around 1% of these women will contract an infection during the pregnancy.
The infection is asymptomatic in 80% of cases and is discovered by testing the blood for toxoplasma antibodies. Those with symptoms may have enlarged lymph nodes ("glands"), fever, tiredness or muscular pains. The risk of transmission to the baby in the first trimester is in the region of 5% compared with nearly 60% in the third trimester. However the risk of that infection to the baby is greatest in those that are infected early in the pregnancy. Because of the risks to the baby and the fact that most infections are asymptomatic, susceptible pregnant women are advised to have monthly blood tests to identify infection with toxoplasma. If this occurs ("seroconversion"), specific treatments can be given that reduce the risk to the baby. Often an amniocentesis is advised to identify those babies infected with the parasite and regular ultrasound scans are performed to identify any effects of the infection of the baby. If no effects are seen then the prognosis is generally very good. If problems are identified then the future parents can be counselled appropriately as to the precise risk and likely outcome. In this case some couples choose to continue with the pregnancy whilst others may choose to end the pregnancy. In either case the full perinatal team (obstetrician, paediatrician, midwife and perinatal psychiatrist) is available to support and advise the couple appropriately.