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Disease Profile

Congenital toxoplasmosis

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Mother-to-child transmission of toxoplasmosis; Toxoplasma embryofetopathy; Toxoplasma embryopathy


Congenital and Genetic Diseases; Nervous System Diseases; Newborn Screening;


The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.

Orpha Number: 858

Congenital toxoplasmosis (CTX) is an embryo-fetopathy characterized by ocular, visceral or intracranial lesions secondary to maternal primo-infection by Toxoplasma gondii (Tg).

Given its infectious origin, incidence of CTX is variable over time and geographically. Screening policies and methods also influence prevalence calculation. A low estimate of the overall prevalence might be of 1:3,030 births, with symptomatic cases at 1:29,000 births.

Clinical description
Clinical presentation is highly variable. Earlier infection is generally more severe but less frequent. Infections in the first trimester may result in miscarriage or fetal death in utero, whereas later ones may be limited to ocular anomalies. Intracranial calcifications, microor macrocephaly, ventricular dilatation and hydrocephalus, hepatomegaly, splenomegaly, cardiomegaly, ascites and intrauterine growth retardation can be observed in infected fetuses. When present, clinical manifestations at birth are maculopapular rash, jaundice, generalized lymphadenopathy, organomegaly, central nervous system anomalies and hyperbilirubinemia, anemia, and thrombocytopenia. The first neurologic manifestation is seizures; nystagmus, hypotonia and, later, delay of developmental milestones acquisition can be seen. The chorioretinitis intracranial calcifications hydrocephalus triad is present in 10% of cases. Ocular involvement may develop after months or years, most frequently with chorioretinitis, followed by microphthalmia and strabismus. Visual impairment is highly dependent on the parasite genotype, and probably on prenatal and postnatal treatments.

CTX is caused by the mother's primo-infection by Tg, an intracellular protozoan parasite of the Apicomplexa phylum, and transmission to the fetus by trans-placental infection. Nearly 25% of exposed fetuses are infected. Mother is infected by Tg through ingestion of ooccysts present in cat faeces and soil, or of cysts present in uncooked meat.

Diagnostic methods
Diagnosis relies on evidence of infection in the fetus, the infant or the child with a history of maternal primo-infection during pregnancy or up to 6 months before conception. Given the poor specificity of clinical signs observed in Tg infection, serological findings and PCR amplification of Tg specific sequences are the main diagnostic clues. RT-PCR targeting repetitive DNA segments was reported to be more sensitive and not less specific than previous tests.

Differential diagnosis
Differential diagnosis includes other congenital infections (rubella, CMV, HSV1 and HSV2, regrouped with Tg infection in the TORCH syndrome) and pseudo-TORCH and Aicardi-Goutières syndromes (see these terms).

Antenatal diagnosis
Fetal ultrasonography and/or magnetic resonance imaging (MRI) detect and characterize brain, cardiac or placental anomalies. Diagnosis is confirmed only with serological or PCR findings of Tg infection in the mother and the amniotic fluid. Amniocentesis should be performed at least 4 weeks after the mother's seroconversion to avoid false negative results due to latency.

Management and treatment
In several countries, a systematic serological status follow-up of each pregnant woman is organized in order to diagnose and treat early maternal and fetal infections. Seronegative pregnant women are tested regularly to detect seroconversion, with, if needed, a spiramycin-based treatment, expected to reduce vertical transmission. A pyrimethamine-sulphonamide combination is recommended in case of confirmed fetal infection. Neonates should also be treated even if they are asymptomatic at birth since complications may occur later. The benefits of prenatal and postnatal treatment remain to be assessed.

Prognosis is highly dependent on the parasite genotype, the gestational age at maternal infection and on the timing of prenatal and postnatal treatment.

Visit the Orphanet disease page for more resources.


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Abnormality of retinal pigmentation
Premature birth
Premature delivery of affected infants
Preterm delivery

[ more ]

5%-29% of people have these symptoms
Low number of red blood cells or hemoglobin
Accumulation of fluid in the abdomen
Enlarged heart
Increased heart size

[ more ]

Cerebral calcification
Abnormal deposits of calcium in the brain
Cognitive impairment
Abnormality of cognition
Cognitive abnormality
Cognitive defects
Cognitive deficits
Intellectual impairment
Mental impairment

[ more ]

Watery stool
Elevated hepatic transaminase
High liver enzymes
Failure to thrive in infancy
Faltering weight in infancy
Weight faltering in infancy

[ more ]

Global developmental delay
Hearing impairment
Hearing defect

[ more ]

Enlarged liver
Too much cerebrospinal fluid in the brain
Intrauterine growth retardation
Prenatal growth deficiency
Prenatal growth retardation

[ more ]

Yellow skin
Yellowing of the skin

[ more ]

Swollen lymph nodes
Flat, discolored area of skin
Abnormally small skull
Decreased circumference of cranium
Decreased size of skull
Reduced head circumference
Small head circumference

[ more ]

Abnormally small eyeball
Muscular hypotonia
Low or weak muscle tone
Involuntary, rapid, rhythmic eye movements
Low platelet count
Visual impairment
Impaired vision
Loss of eyesight
Poor vision

[ more ]



Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Newborn Screening

  • Baby's First Test is the nation's newborn screening education center for families and providers. This site provides information and resources about screening at the local, state, and national levels and serves as the Clearinghouse for newborn screening information.
  • The Newborn Screening Coding and Terminology Guide has information on the standard codes used for newborn screening tests. Using these standards helps compare data across different laboratories. This resource was created by the National Library of Medicine.
  • National Newborn Screening and Global Resource Center (NNSGRC) provides information and resources in the area of newborn screening and genetics to benefit health professionals, the public health community, consumers and government officials.

Learn more

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.

In-Depth Information

  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.