Skip directly to search Skip directly to A to Z list Skip directly to navigation Skip directly to page options Skip directly to site content

Resources for Health Professionals

On this Page

Diagnosis

Diagnosis of toxoplasmosis is usually made by detection of Toxoplasma-specific IgG, IgM, IgA, or IgE 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)
  • Agglutination test
  • Avidity test

If acute infection is suspected, the patient’s serum should be tested for IgG and IgM Toxoplasma-specific antibodies. Some serological tests are available at commercial laboratories. However, due to the inherent difficulty in diagnosing acute toxoplasmosis, physicians are advised to seek confirmatory testing through the reference laboratory at Palo Alto Medical Foundation Toxoplasma Serology Laboratory.

For more information: http://www.pamf.org/serology/

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.

Eye disease is diagnosed primarily by ocular examination.

Treatment

Currently recommended treatment drugs for toxoplasmosis target the tachyzoite stage of the parasite and do not eradicate encysted parasites in the tissues. Pyrimethamine, considered the most effective drug against toxoplasmosis, is a standard component of therapy. Pyrimethamine is a folic acid antagonist and can cause dose-related suppression of the bone marrow, which is mitigated by concurrent administration of folinic acid (leucovorin). Leucovorin protects the bone marrow from the toxic effects of pyrimethamine. A second drug, such as sulfadiazine or clindamycin (if the patient has a hypersensitivity reaction to sulfa drugs), should also be included. 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 Practice of Infectious Diseases, 8th, Edition, 2017  Mandell GL, Bennett JE, Dolin R, Eds. Churchill Livingstone Elsevier, Philadelphia, PA.)

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 inflammation, visual acuity, and lesion size, location, and persistence. Healed lesions should not be treated. The “classic therapy” for ocular toxoplasmosis consists of the following:

  • Adults: pyrimethamine 100 mg for 1 day as a loading dose, then 25 to 50 mg per day, plus sulfadiazine 2 to 4 grams daily for 2 days, followed by 500mg to 1 gram dose 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)
  • Therapy should be given for 4 to 6 weeks, followed by reevaluation of the patient’s condition. (See: 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 women whose infections were acquired and diagnosed before 18 weeks gestation and infection of the fetus is not documented or suspected. Spiramycin acts to reduce transmission to the fetus and is most effective if initiated within 8 weeks of seroconversion. Spiramycin can be obtained from the U.S. Food and Drug Administration, telephone 301-796-1400. Pyrimethamine, sulfadiazine and leucovorin are recommended for infections acquired at or after 18 weeks gestation or infection in the fetus is documented or suspected. PCR is often performed on the amniotic fluid at 18 gestation weeks to determine if the infant is infected.

For additional information regarding management of toxoplasmosis in pregnant women, see Montoya JG, Remington JS. Management of Toxoplasma gondii infection in pregnancy. Clin Infect Dis 2008 ;47:554-566 and Maldonado YA, Read JS, AAP Committee on Infectious Diseases. Diagnosis, treatment, and prevention of congenital toxoplasmosis in the United States. Pediatrics. 2017;139(2):e20163860.

Congenitally infected newborns are generally treated with pyrimethamine, a sulfonamide, and leucovorin for 12 months. Recommendations from the National Reference Laboratory for Toxoplasmosis (PAMF-TSL) and the Toxoplasmosis Center at the University of Chicago for treatment of congenitally infected infants are:

  • Pyrimethamine: 2 mg/kg per day orally, divided twice per day for the first 2 days; then from day 3 to 2 months (or 6 months if symptomatic) 1 mg/kg per day, orally, every day; then 1 mg/kg per day, orally, 3 times per week
  • Sulfadiazine: 100 mg/kg per day, orally, divided twice per day
  • Folinic acid (leucovorin): 10 mg, 3 times per week
  • See Maldonado YA, Read JS, AAP Committee on Infectious Diseases. Diagnosis, treatment, and prevention of congenital toxoplasmosis in the United States. Pediatrics. 2017;139(2):e20163860.

Toxoplasmosis in immunodeficient patients is often fatal if not treated. Treatment is recommended for at least 4 to 6 weeks beyond resolution of all clinical signs and symptoms, but may be required for 6 months or longer. Relapses are known to occur in AIDS patients and maintenance therapy is recommended until a significant immunologic improvement is achieved in response to antiretroviral therapy. Pyrimethamine, folinic acid (leucovorin), and sulfadiazine are standards of therapy for immunodeficient patients. For additional information, see Guidelines for the Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents and Guidelines for the Prevention and Treatment of Opportunistic Infections Among HIV-Exposed and HIV-Infected Children.

Related Links

  • Preventing congenital toxoplasmosis
  • Maldonado YA, Read JS, AAP Committee on Infectious Diseases. Diagnosis, treatment, and prevention of congenital toxoplasmosis in the United States. Pediatrics. 2017;139(2):e20163860
  • 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.

TOP