Toxoplasmosis
Toxoplasmosis: Excerpt from The 5-Minute Pediatric Consult
Richard M. Rutstein, MD
Toxoplasmosis - BASICS
Toxoplasmosis - description
Toxoplasma gondii is an intracellular protozoan parasite with a complex life cycle; its definitive host is the cat. In addition to causing asymptomatic infection and clinical disease in humans, the organism is capable of causing asymptomatic and symptomatic infections in a wide range of other mammals and birds.
- Pitfalls:
- Failure to consider diagnosis in at-risk or symptomatic infant
- Failure to consider the significant risk of late sequelae in asymptomatic exposed/infected neonate and therefore failure to offer therapy to asymptomatic infected neonate.
Toxoplasmosis - general prevention
- Avoidance of undercooked meats
- Seronegative women need to exercise caution in caring for cats.
- Maternal/Neonatal antibody screening is important in areas with a significant incidence of toxoplasmosis.
- Treatment of pregnant women with documented seroconversion may prevent congenital infection in many cases.
- If fetal infection is established, aggressive treatment during pregnancy with spiramycin, pyrimethamine, and sulfonamide may palliate the severity of the disease in the infant.
Toxoplasmosis - epidemiology
- The rate of acquired infection, usually asymptomatic, varies widely through the world and increases with age.
- 70–90% of children with congenital toxoplasmosis are asymptomatic at birth. Late sequelae (e.g., chorioretinitis, mental retardation, seizures, sensorineural hearing loss) occur in >50% of untreated infants considered asymptomatic at birth.
Toxoplasmosis - incidence
Worldwide, the incidence of congenital infection ranges from 1–7/1,000 live births; in the US, incidence is estimated at 0.1–1/1,000 live births. It is believed that 400–4,000 infants are born annually in the US with congenital toxoplasmosis.
Toxoplasmosis - prevalence
Seroprevalence rates among pregnant women vary from 4–80% worldwide; in the US, a serologic survey found 15% of women of child-bearing age were seropositive.
Toxoplasmosis - pathophysiology
- Toxoplasmosis is acquired by the ingestion of oocysts or intact viable tissue cysts in inadequately cooked meat.
- After ingestion, the oocysts and cysts are disrupted by the digestive process, and viable infective organisms cross the GI lining. Hematologic spread leads to infection of multiple organs, most notably the heart, skeletal muscle, and the brain. There, slowly growing or dormant cysts remain for the patient’s lifetime.
- Congenital toxoplasmosis generally occurs during a primary maternal infection. An exception may be when the pregnant woman is severely immunocompromised; congenital infection has occurred in children of HIV-infected women with latent toxoplasmosis infection.
- Primary infection in the 1st trimester is associated with a higher incidence of symptomatic congenital disease, although most congenital infections occur late in pregnancy, and affected neonates have subclinical infection at birth. Overall, 30–40% of infants born to mothers with primary infection during pregnancy will be congenitally infected.
Toxoplasmosis - DIAGNOSIS
Toxoplasmosis - signs & symptoms
Toxoplasmosis - history
- For acquired infection: History of contact with cats; eating raw or undercooked meat (especially pork)
- For congenital infection: History of maternal exposure or positive titers (IgG and/or IgM)
Toxoplasmosis - physical exam
- Acquired infection: Adenopathy, rash, fever, malaise, hepatosplenomegaly
- Congenital infection: Microcephaly or macrocephaly, hydrocephalus, chorioretinitis, hepatosplenomegaly, petechiae, sensorineural hearing loss, intracerebral calcifications
Toxoplasmosis - tests
Toxoplasmosis - lab
- Screen all pregnant women or their infants in high-incidence areas by use of toxoplasmosis-specific IgM or rise in IgG titer over time.
- Several states now mandate neonatal screening; filter paper test for IgM, detects 75% of cases, many asymptomatic
- For the at-risk neonate, diagnosis is made by demonstration of specific IgM, IgA, or IgE titers, or rise in IgG titers, and/or clinical symptoms in infant of mother with recent primary infection.
- Thrombocytopenia
- Elevated result on liver function tests
Toxoplasmosis - imaging
Head CT or MRI demonstrating calcifications
Toxoplasmosis - diag proced-surgery
Early and frequent audiologic and ophthalmic evaluations are a necessity. Many affected infants will have normal results of neonatal examinations.
Toxoplasmosis - differencial diagnosis
- Primary infection: Acute disease symptoms of adenopathy, fever, rash: Primary Epstein–Barr virus, cytomegalovirus, HIV infection
- For the newborn with micro/macrocephaly, hepatosplenomegaly, eye disease; other congenital infections: Cytomegalovirus, syphilis, rubella
Toxoplasmosis - TREATMENT
Toxoplasmosis - medication
- Pyrimethamine and sulfadiazine for the 1st year of life for all congenitally infected infants, whether symptomatic or not.
- Folic acid is given during the course of therapy to minimize hematologic side effects.
Toxoplasmosis - FOLLOW UP
- Continued attention to neurologic development and frequent audiologic and ophthalmic evaluations throughout the 1st few years of life
- For children with early symptomatic disease, careful attention to neurologic condition and early intervention services to optimize outcome
Toxoplasmosis - prognosis
- Most acquired infections are asymptomatic or associated with mild short-lived symptoms.
- Most congenital infections are asymptomatic, although late sequelae occur in >50% of untreated infants.
- Symptomatic newborns are at significant risk for sequelae, most frequently neurologic (e.g., hydrocephalus, retardation) or ophthalmologic (e.g., retinitis, blindness).
- Prenatal treatment appears to decrease risk to newborn; therapy of all infected infants, symptomatic or not, for 1 year, improves outcome.
Toxoplasmosis - complications
- Congenital infection: Retardation, retinitis, hydrocephalus, seizures, microcephaly, sensorineural hearing loss
- Acquired infection (all rare): Adenopathy, mononucleosis-like syndrome, myocarditis, pneumonia, meningitis/encephalitis
Toxoplasmosis - bibliography
- European Multicentre Study on Congenital Toxoplasmosis. Effect of timing and type of treatment on the risk of mother to child transmission of Toxoplasma gondii. BJOG. 2003;110:112–120.
- Hill D, Dubey JP. Toxoplasma gondii: Transmission, diagnosis and prevention. Clin Microbiol Infect. 2002;8:634–640.
- Jones JL, Lopez A, Wilson M, et al. Congenital toxoplasmosis: A review. Obstet Gynecol Surv. 2001;56:296–305.
- McLeod R, Boyer K, Karrison T, et al. Outcome of treatment for congenital toxoplasmosis, 1981–2004: The National Collaborative Chicago-Based, Congenital Toxoplasmosis Study. Clin Infect Dis. 2006;42:1383–1394.
- Montoya JG. Laboratory diagnosis of Toxoplasma gondii infection and toxoplasmosis. J Infect Dis. 2002;185(Suppl 1):S73–S82.
Toxoplasmosis - CODES
Toxoplasmosis - icd9
130.9 Toxoplasmosis, unspecified
Toxoplasmosis - FAQ
- Q: What is the risk of congenital infection in a mother with stable toxoplasmosis?
- A: The risk of congenital infection in the child of a mother with long-standing toxoplasmosis infection is considered low; the exception is for mothers with a significant degree of immunosuppression or deficiency.
- Q: What is the risk of congenital infection in children of a mother with documented primary infection during pregnancy?
- A: ~30–40% of infants born to mothers with primary infection during pregnancy will be infected themselves. This rate may be lower if the mother receives therapy (spiramycin or pyrimethamine/sulfadiazine) prenatally. Of the infected infants, most (70–90%) are normal at birth; with treatment for 12 months, it appears most will have a favorable outcome.
Book Source Details
- Book Title: The 5-Minute Pediatric Consult
- Author(s): M. William Schwartz MD; et al.
- Year of Publication: 2008
- Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: The 5-Minute Pediatric Consult
Authors: M. William Schwartz MD; et al.
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7577-9
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