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Diagnosis
Diagnosis of toxoplasmosis is usually made by detection of Toxoplasma-specific IgG, IgM, or IgA antibodies. There are several tests available that detect these immunoglobulin antibodies within several weeks of infection:
- dye test (DT)
- indirect fluorescent antibody test (IFA)
- enzyme immunoassays (ELISA, immunoblots)
If acute infection is suspected, the patient’s serum should be tested for IgG and IgM Toxoplasma-specific antibodies. For a testing results algorithm, see CDC’s DPDx Toxoplasmosis: Antibody Detection page.
Serologic tests are sometimes unreliable in immunosuppressed patients. Because of the persistence of Toxoplasma cysts and antibody in asymptomatic chronic latent infections, immunosuppressed persons with both positive PCR and serologic results should have their diagnostic testing results interpreted in relation to clinical features of an active infection. A negative PCR does not rule out active infection. PCR can also be performed on amniotic fluid which can be helpful in determining fetal infection following acute acquired infection of the mother.
Diagnosis can be made by direct observation of the parasite in stained tissue sections, cerebrospinal fluid (CSF), or other biopsy material. These techniques are used less frequently because of the difficulty of obtaining these specimens. Parasites can also be isolated from blood or other body fluids (for example, CSF) but this process can be difficult and requires considerable time.
Treatment
Treatment of immunocompetent adults with lymphadenopathic toxoplasmosis is rarely indicated; this form of the disease is usually self-limited. If visceral disease is clinically evident or symptoms are severe or persistent, treatment may be indicated for 2 to 4 weeks. Treatment for ocular diseases should be based on a complete ophthalmologic evaluation. The decision to treat ocular disease is dependent on numerous parameters including acuteness of the lesion, degree if inflamation, visual acuity, and lesion size, location, and persistance (for example, “classic therapy” for ocular toxoplasmosis, adults: pyrimethamine 100 mg for 1 day as a loading dose, then 25 to 50 mg per day, plus sulfadiazine 1 gram four times per day, plus folinic acid (leucovorin) 5-25 mg with each dose of pyrimethamine; pediatric dose: pyrimethamine 2 mg/kg first day then 1 mg/kg each day, plus sulfadiazine 50 mg/kg two times per day, plus folinic acid (leucovorin) 7.5 mg per day) for 4 to 6 weeks followed by reevaluation of the patient’s condition. Leucovorin protects the bone marrow from the toxic effects of pyrimethamine. If the patient has a hypersensitivity reaction to sulfa drugs, pyrimethamine plus clindamycin can be used instead. The fixed combination of trimethoprim with sulfamethoxazole has been used as an alternative, as well as other drugs such as atovaquone and pyrimethamine plus azithromycin, which have not been extensively studied (see: Montoya JG, Boothroyd JC, Kovacs JA. Toxoplasma gondii in Mandell, Douglas, and Bennett’s Principles and Preactice of Infectious Diseases, 7th, Edition, 2010. Mandell GL, Bennett JE, Dolin R, Eds. Churchill Livingstone Elsevier, Philadelphia, PA.; and de-la-Torre A, Stanford M, Curi A, Jaffe GJ, Gomez-Marin JE. Therapy for ocular toxoplasmosis. Ocul Immunol Inflamm. 2011;19:314-20. Corticosteroids are sometimes prescribed in addition to antiparasitic agents.
Management of maternal and fetal infection varies depending on the treatment center. In general, spiramycin is recommended (for the first and early second trimesters) or pyrimethamine/sulfadiazine and leucovorin (for late second and third trimesters) for women with acute T. gondii infection diagnosed at a reference laboratory during gestation. PCR is often performed on the amniotic fluid at 18 gestation weeks to determine if the infant is infected. If the infant is likely to be infected, then treatment with drugs such as pyrimethamine, sulfadiazine, and leucovorin is typical. Congenitally infected newborns are generally treated with pyrimethamine, a sulfonamide, and leucovorin for 1 year (see Montoya JG, Liesenfeld O. Toxoplasmosis. Lancet. 2004 Jun 12;363:1965-1976; for additional information regarding management in pregnant women, see Montoya JG, Remington JS. Management of Toxoplasma gondii infection in pregnancy. Clin Infect Dis 2008;47:554-566).
Persons with HIV infection who develop active toxoplasmosis (usually toxoplasmic enchephalitis) need treatment that must be taken until a significant immunologic improvement is achieved as a result of antiretroviral therapy (see Guidelines for Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents; and for children see Guidelines for the Prevention and Treatment of Opportunistic Infections Among HIV-Exposed and HIV-Infected Children at https://aidsinfo.nih.gov/contentfiles/lvguidelines/oi_guidelines_pediatrics.pdf).
Related Links
- Preventing congenital toxoplasmosis
- Montoya JG, Liesenfeld. Toxoplasmosis. Lancet. 2004 Jun 12;363:1965-1976.
To access this article online via the Lancet website you must either be a subscriber or choose the pay-per-view option. - Toxoplasmosis Brochures (Educational Material for Patients)
This information is provided as an informational resource for licensed health care providers as guidance only. It is not intended as a substitute for professional judgment.
Pyrimethamine
Note on Treatment in Pregnancy
Pyrimethamine is in pregnancy category C. Data on the use of pyrimethamine in pregnant women are limited. Pyrimethamine is commonly used in combination with sulfadiazine and folinic acid for treatment of fetal toxoplasmosis during the 2nd and 3rd trimesters. In malaria prevention interventions for which the World Health Organization (WHO) has determined that the benefit of treatment outweighs the risk, WHO allows use of pyrimethamine in combination with sulfadoxine in the 2nd and 3rd trimesters. Available evidence suggests avoiding pyrimethamine during the 1st trimester and supplementing pyrimethamine with folinic acid in pregnant women.
Pregnancy Category C: Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal, or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the fetus.
Note on Treatment During Lactation
Pyrimethamine is excreted in breast milk. Both the American Academy of Pediatrics and the WHO classify pyrimethamine to be compatible with breast-feeding. Pyrimethamine when used in combination with other drugs should be used with caution in breast-feeding women.
Note on Treatment in Pediatric Patients
The safety of pyrimethamine in children has not been established. In malaria prevention interventions for which the WHO has determined that the benefit of treatment outweighs the risk, WHO allows use of pyrimethamine in combination with sulfadoxine in children during the first year of life. Pyrimethamine is listed as an antipneumocystosis and antitoxoplasmosis medicine on the WHO Model List of Essential Medicines for Children, intended for the use of children up to 12 years of age.
Sulfadiazine
Note on Treatment in Pregnancy
Sulfadiazine is in pregnancy category C. Data on the use of sulfadiazine in pregnant women are limited. Available evidence suggests avoiding sulfonamides after week 32 of pregnancy. Sulfadiazine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Pregnancy Category C: Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal, or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the fetus.
Note on Treatment During Lactation
Sulfadiazine is excreted in breast milk. The World Health Organization (WHO) recommends avoiding breastfeeding with sulfadiazine treatment. Sulfadiazine is contraindicated for use during lactation.
Note on Treatment in Pediatric Patients
The safety of sulfadiazine in children has not been established. Use in children age 2 months and younger is contraindicated unless used in the treatment of congenital toxoplasmosis. Sulfadiazine is listed as an antipneumocystosis and antitoxoplasmosis medicine on the WHO Model List of Essential Medicines for Children, intended for the use of children up to 12 years of age.
Clindamycin
Note on Treatment in Pregnancy
Clindamycin is in pregnancy category B. Data on the use of clindamycin in pregnant women are limited, although no congenital anomalies have been reported. Clindamycin may be used during pregnancy in those patients who will clearly benefit from the drug.
Pregnancy Category B: Either animal-reproduction studies have not demonstrated a fetal risk but there are no controlled studies in pregnant women or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the first trimester (and there is no evidence of a risk in later trimesters).
Note on Treatment During Lactation
Clindamycin is excreted in breast milk. The American Academy of Pediatrics classifies clindamycin as usually compatible with breastfeeding.
Note on Treatment in Pediatric Patients
The parenteral form of clindamycin contains benzyl alcohol, which has been associated with a fatal “gasping syndrome” in premature infants.
Trimethoprim–sulfamethoxazole
Note on Treatment in Pregnancy
Trimethoprim–sulfamethoxazole (TMP–SMX) is in pregnancy category C. TMP–SMX should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. TMP-SMX should be avoided near-term because of the potential for hyperbilirubinemia and kernicterus in the newborn.
Pregnancy Category C: Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal, or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the fetus.
Note on Treatment During Lactation
Trimethoprim–sulfamethoxazole (TMP–SMX) is excreted in breast milk. TMP–SMX generally is compatible with breastfeeding of healthy, full-term infants after the newborn period. However, TMP-SMX generally should be avoided by women when nursing infants who are premature, jaundiced, ill, or stressed, or who have glucose-6-phosphate dehydrogenase deficiency.
Note on Treatment in Pediatric Patients
The safety of trimethoprim–sulfamethoxazole (TMP–SMX) in children has not been systematically evaluated. Use in children less than 2 months of age generally is not recommended.
- Page last reviewed: April 10, 2017
- Page last updated: April 10, 2017
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