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CNS signs are the most common presentation in immunocompromised patients suffering ''Toxoplasma'' infection or re-activation. Signs are due to intracranial mass lesions or encephalitis, and can include headaches, seizures, pyrexia, coma and focal neurological deficits. Ocular involvement is also possible and usually results from re-activation of a congenital infection. Inflammation of the choroid causes pain and visual disturbances. Occasionally, in severely immunocompromised patients, disease can be seen outwith the CNS and the eye. In these incidences, affected tissues and therefore clinical signs can be variable. For example, patients may suffer pneumonitis, myocarditism, high fevers or chills and polymyositis. Unless treated, these disseminated infections may be fatal.

CNS signs are the most common presentation in immunocompromised patients suffering ''Toxoplasma'' infection or re-activation. Signs are due to intracranial mass lesions or encephalitis, and can include headaches, seizures, pyrexia, coma and focal neurological deficits. Ocular involvement is also possible and usually results from re-activation of a congenital infection. Inflammation of the choroid causes pain and visual disturbances. Occasionally, in severely immunocompromised patients, disease can be seen outwith the CNS and the eye. In these incidences, affected tissues and therefore clinical signs can be variable. For example, patients may suffer pneumonitis, myocarditism, high fevers or chills and polymyositis. Unless treated, these disseminated infections may be fatal.

Congenital toxoplasmosis: This type results from a primary, often asymptomatic infection acquired by the mother during pregnancy. Women infected before conception ordinarily do not transmit toxoplasmosis to the fetus unless the infection is reactivated during pregnancy by immunosuppression. Spontaneous abortion and stillbirth may occur. The percentage of surviving fetuses born with toxoplasmosis depends on when maternal infection is acquired; it increases from 15% during the 1st trimester to 30% during the 2nd to 60% during the 3rd.

When infection is acquired for the first time during pregnancy, congenital toxoplasmosis can arise. This nmay also occur if a mother infected before conception becomes immunosuppressed during pregnancy. Foetuses infected congenitally may be aborted, stillborn, or born with toxoplasmosis. Infections later in gestation are more likely to give rise to a live but infected neonate. When neonates are born with toxoplasmosis disease can be severe, particularly if transplacental infection occured early in pregnancy. Signs can include rashes, icterus and hepatosplenomegaly, and there are four abnormalities that are characteristic of congenital toxoplasmosis: retinochoroiditis, cerebral calcifications, hydrocephalus/microcephaly, and psychomotor retardation. Prognosis is poor. Many children with less severe infections and most infants born to mothers infected during the 3rd trimester appear healthy at birth but are at high risk of seizures, intellectual disability, retinochoroiditis, or other symptoms developing months or even years later.

 

Disease in neonates may be severe, particularly if acquired early in pregnancy; symptoms include jaundice, rash, hepatosplenomegaly, and the characteristic tetrad of abnormalities: bilateral retinochoroiditis, cerebral calcifications, hydrocephalus or microcephaly, and psychomotor retardation. Prognosis is poor. Many children with less severe infections and most infants born to mothers infected during the 3rd trimester appear healthy at birth but are at high risk of seizures, intellectual disability, retinochoroiditis, or other symptoms developing months or even years later.