Toxoplasmosis in Emergency Medicine Workup

  • Author: Joseph U Becker, MD; Chief Editor: Rick Kulkarni, MD   more...
 
Updated: Mar 10, 2010
 

Laboratory Studies

  • Results from basic laboratory studies such as complete blood cell count (CBC), chemistries, and liver function tests (LFTs) are typically normal, although lymphocytosis may be present.
  • Indirect detection
    • Indirect detection is performed in pregnant women and immunocompromised patients.
    • Detection of immunoglobulin G (IgG) is possible within 2 weeks of infection using enzyme-linked immunoassay (ELISA), IgG avidity test, and agglutination and differential agglutination test. The presence of IgG indicates a likely past infection, while the presence of IgM usually indicates acute infection (particularly in the absence of IgG). However, IgM has, in some cases, been documented to persist for months or years. Lack of IgG and IgM may exclude infection. IgM alone that then transitions to IgG without IgM or both IgG and IgM indicates likely acute infection. There is a significant rate of IgM false positivity.
    • The sensitivities and specificities of the commercially available IgM and IgG tests vary substantially.
    • Acute and convalescent sera have no role.
    • Sabin-Feldman dye test: Live organisms are used to demonstrate the presence of anti-T gondii antibodies. This test is primarily used as a confirmatory test at reference laboratories.
    • IgG avidity test: IgG produced early in infection is less avid and binds to T gondii antigens more weakly than antibodies produced later in the course of infection. High antibody avidity indicates an older, earlier infection. This test may be helpful in the setting of pregnancy, as the timing of infection has prognostic value.
  • Direct detection
    • Polymerase chain reaction (PCR) amplification of T gondii genes is possible (samples may be taken of the CSF, blood, lymph node, or tissue biopsies or aqueous humor).
    • Tachyzoites may be demonstrated in tissues or smears obtained from biopsy. They also can be seen in CSF. CSF also shows mononuclear pleocytosis and elevated protein level. Tachyzoites demonstrate acute infection, while tissue cysts and bradyzoites are seen in chronic/latent infection but may be present in acute infection/reactivation.
    • Culture: T gondii may be isolated from the blood via either inoculation of human cell lines or mouse inoculation. Mouse inoculation may require a longer time to yield results and also is likely to be more expensive.
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Imaging Studies

  • MRI is more sensitive than CT (and CT with contrast is more sensitive than without) for detecting brain lesions due to toxoplasmosis. One study showed that MRI detected abnormalities in 40% of patients whose abnormalities were not detected on CT.[16]
  • Typical CNS findings include multiple ring-enhancing lesions with associated brain edema, although single lesions are also seen (also see Toxoplasmosis, CNS).
  • Single-photon computed tomography (SPECT) is useful in distinguishing between CNS lymphoma and infection (ie, toxoplasmosis or any other infection).
  • Fetal or neonatal ultrasonography can be useful in cases of known or suspected maternal acute infection and transplacental infection. Findings are generally nonspecific but include ventriculomegaly and CNS calcifications, particularly in the basal ganglia.
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Procedures

  • Lumbar puncture (after imaging to identify evidence of increased intracranial pressure [ICP])
  • Brain biopsy
  • Lymph node biopsy
  • Amniocentesis
  • Bronchoalveolar lavage
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Contributor Information and Disclosures
Author

Joseph U Becker, MD  Fellow, Global Health and International Emergency Medicine, Stanford University School of Medicine

Joseph U Becker, MD is a member of the following medical societies: American College of Emergency Physicians, Emergency Medicine Residents Association, Phi Beta Kappa, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Coauthor(s)

Deepika Singh, MD  Staff Physician, Department of Emergency Medicine, Lawrence and Memorial Hospital, New London, CT

Deepika Singh, MD is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, American Nurses Association, Emergency Medicine Residents Association, and Sigma Theta Tau International

Disclosure: Nothing to disclose.

Richard H Sinert, DO  Associate Professor of Emergency Medicine, Clinical Assistant Professor of Medicine, Research Director, State University of New York College of Medicine; Consulting Staff, Department of Emergency Medicine, Kings County Hospital Center

Richard H Sinert, DO is a member of the following medical societies: American College of Physicians and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

Theodore J Gaeta, DO, MPH, FACEP  Clinical Associate Professor, Department of Emergency Medicine, Weill Cornell Medical College; Vice Chairman and Program Director of Emergency Medicine Residency Program, Department of Emergency Medicine, New York Methodist Hospital; Academic Chair, Adjunct Professor, Department of Emergency Medicine, St George's University School of Medicine

Theodore J Gaeta, DO, MPH, FACEP is a member of the following medical societies: Alliance for Clinical Education, American College of Emergency Physicians, Clerkship Directors in Emergency Medicine, Council of Emergency Medicine Residency Directors, New York Academy of Medicine, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Mark L Plaster, MD, JD  Executive Editor, Emergency Physicians Monthly

Mark L Plaster, MD, JD is a member of the following medical societies: American Academy of Emergency Medicine and American College of Emergency Physicians

Disclosure: M L Plaster Publishing Co LLC Ownership interest Management position

John D Halamka, MD, MS  Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center

John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Chief Editor

Rick Kulkarni, MD  Attending Physician, Department of Emergency Medicine, Cambridge Health Alliance, Division of Emergency Medicine, Harvard Medical School

Rick Kulkarni, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine

Disclosure: WebMD Salary Employment

Acknowledgments

The authors and editors of eMedicine gratefully acknowledge the contributions of previous author, Joseph Sciammarella, MD, to the development and writing of this article.

References

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  2. [Guideline] Kaplan JE, Benson C, Holmes KH, Brooks JT, Pau A, Masur H. Guidelines for prevention and treatment of opportunistic infections in HIV-infected adults and adolescents: recommendations from CDC, the National Institutes of Health, and the HIV Medicine Association of the Infectious Diseases Society of America. MMWR Recomm Rep. Apr 10 2009;58:1-207; quiz CE1-4. [Medline].

  3. Jones JL, Kruszon-Moran D, Sanders-Lewis K, Wilson M. Toxoplasma gondii infection in the United States, 1999 2004, decline from the prior decade. Am J Trop Med Hyg. Sep 2007;77(3):405-10. [Medline].

  4. Torok E, Moran E, Cooke F. Toxoplasmosis. In: Oxford Handbook of Infectious Diseases and Microbiology. Vol 1. New York: Oxford University Press; 2009:567.

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  7. Holland GN, Crespi CM, ten Dam-van Loon N, et al. Analysis of recurrence patterns associated with toxoplasmic retinochoroiditis. Am J Ophthalmol. Jun 2008;145(6):1007-1013. [Medline].

  8. Montoya JG, Remington JS. Toxoplasmic chorioretinitis in the setting of acute acquired toxoplasmosis. Clin Infect Dis. Aug 1996;23(2):277-82. [Medline].

  9. Gras L, Wallon M, Pollak A, et al. Association between prenatal treatment and clinical manifestations of congenital toxoplasmosis in infancy: a cohort study in 13 European centres. Acta Paediatr. Dec 2005;94(12):1721-31. [Medline].

  10. Luft BJ, Remington JS. Toxoplasmic encephalitis in AIDS. Clin Infect Dis. Aug 1992;15(2):211-22. [Medline].

  11. Porter SB, Sande MA. Toxoplasmosis of the central nervous system in the acquired immunodeficiency syndrome. N Engl J Med. Dec 3 1992;327(23):1643-8. [Medline].

  12. Hofman P, Bernard E, Michiels JF, Thyss A, Le Fichoux Y, Loubiere R. Extracerebral toxoplasmosis in the acquired immunodeficiency syndrome (AIDS). Pathol Res Pract. Sep 1993;189(8):894-901. [Medline].

  13. Thiebaut R, Leproust S, Chene G, Gilbert R. Effectiveness of prenatal treatment for congenital toxoplasmosis: a meta-analysis of individual patients' data. Lancet. Jan 13 2007;369(9556):115-22. [Medline].

  14. Desmonts G, Couvreur J. Congenital toxoplasmosis. A prospective study of 378 pregnancies. N Engl J Med. May 16 1974;290(20):1110-6. [Medline].

  15. Sacktor N, Lyles RH, Skolasky R, et al. HIV-associated neurologic disease incidence changes:: Multicenter AIDS Cohort Study, 1990-1998. Neurology. Jan 23 2001;56(2):257-60. [Medline].

  16. Levy RM, Mills CM, Posin JP, Moore SG, Rosenblum ML, Bredesen DE. The efficacy and clinical impact of brain imaging in neurologically symptomatic AIDS patients: a prospective CT/MRI study. J Acquir Immune Defic Syndr. 1990;3(5):461-71. [Medline].

 
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Ophthalmic toxoplasmosis. Used with permission of Anton Drew, ophthalmic photographer, Adelaide, South Australia.
 
 
 
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