You have been logged out of VisualDx or your session has expired.

Please reload this page and sign into VisualDx to continue.

..
  VisualDx Mobile   Select Language

Get VisualDx Mobile

There are VisualDx mobile apps available for iOS and Android devices.

You will need a VisualDx account to use the mobile apps.



Already have an account? Sign In or
sign up for a free trial.

Users with VisualDx accounts earn CME credits for using VisualDx.

Already have an account? Sign In or
sign up for a free trial.

Create a Personal Account

E-mail (username)
Password
Verify Password
First Name
Last Name

Personal Account Created

Mobile Access

You can now download VisualDx for your iOS and Android devices. Launch the VisualDx app from your device and sign in using your VisualDx personal account username and password.

CME Certification

Sign in with your personal account to earn and claim CME credits through VisualDx. Credits can be earned by building a differential or looking up a diagnosis.

Version: 7.11.1423   (build b7dc603)
Select Language


Select Region

Send us your feedback

E-mail
Message
This field is required

Oops! There was an issue during submission. Please try again. If the problem persists, email feedback@visualdx.com with your feedback.

Thank You!

We appreciate your feedback and you will be hearing from us soon.

OK

Share This Page

Thank You!

We have sent an e-mail with a link to the current page.

OK

E-mail This Patient Information Sheet

Thank You!

We have sent an e-mail with this patient information.

OK

Image Contributors

Individuals

  • Christine Ahn MD
    Carl Allen DDS, MSD
    Brandon Ayres MD
    Howard P. Baden MD
    Robert Baran MD
    Keira Barr MD
    Gregory J. Basura MD, Ph.D
    Donald Belsito MD
    Jeffrey D. Bernhard MD
    Jesse Berry MD
    Victor Blanco MD
    Benjamin R. Bohaty MD
    William Bonnez MD
    Sarah Brenner MD
    Robert A. Briggaman MD
    Robert Brodell MD
    Roman Bronfenbrener MD
    Walter Brooks MD
    William Buckley MD
    Philip Bulterys MD, PhD (candidate)
    Susan Burgin MD
    Sonya Burton MD
    Sean P. Bush MD, FACEP
    Jeffrey Callen MD
    Scott Camazine MD
    Michael Cardwell
    Shelley D. Cathcart MD
    Robert Chalmers MD, MRCP, FRCP
    Chia-Yu Chu MD, PhD
    Flavio Ciferri MD
    Maria Rosa Cordisco MD
    Noah Craft MD, PhD
    John T. Crissey MD
    Harold E. Cross MD, PhD
    Charles Crutchfield III MD
    Adriana Cruz MD
    Donna Culton MD, PhD
    Bart J. Currie MBBS, FRACP, DTM&H
    Chicky Dadlani MD
    Alexander Dane DO
    C. Ralph Daniel III MD
    Thomas Darling MD, PhD
    William Delaney MD
    Damian P. DiCostanzo MD
    Ncoza Dlova MD
    James Earls MD
    Libby Edwards MD
    Melissa K. Egge MD
    Charles N. Ellis MD
    Rachel Ellis MD
    David Elpern MD
    Nancy Esterly MD
    Stephen Estes MD
    E. Dale Everett MD
    Janet Fairley MD
    David Feingold MD
    Benjamin Fisher MD
    Henry Foong MBBS, FRCP
    David Foster MD, MPH
    Brian D. Foy PhD
    Michael Franzblau MD
    Vincent Fulginiti MD
    Sunir J. Garg MD, FACS
    Kevin J. Geary MD
    Lowell Goldsmith MD, MPH
    Sethuraman Gomathy MD
    Bernardo Gontijo MD, PhD
    Kenneth Greer MD
    Kenneth G. Gross MD
    Alan Gruber MD
    Nathan D. Gundacker MD
    Akshya Gupta MD
    Vidal Haddad MSC, PhD, MD
    Edward Halperin MD, MA
    Ronald Hansen MD
    John Harvey
    Rizwan Hassan MD
    Michael Hawke MD
    Jason E. Hawkes MD
    Peter W. Heald MD
    David G. Hicks MD
    Sarah Hocker DO
    Ryan J. Hoefen MD, PhD
    Li-Yang Hsu MD
    William Huang MD
    Sanjana Iyengar MD
    Alvin H. Jacobs MD
    Saagar Jadeja MD
    Shahbaz A. Janjua MD
    Joshua J. Jarvis MD
    Kit Johnson
    Robert Kalb MD
    A. Paul Kelly MD
    Henry Kempe MD
    Loren Ketai MD
    Sidney Klaus MD
    Ashwin Kosambia MD
    Jessica A. Kozel MD
    Carl Krucke
    Mario E. Lacouture MD
    Joseph Lam MD
    Alfred T. Lane MD
    Edith Lederman MD
    Nahyoung Grace Lee MD
    Pedro Legua MD, PhD
    Robert Levin MD
    Bethany Lewis MD
    Sue Lewis-Jones FRCP, FRCPCH
    Taisheng Li MD
    Christine Liang MD
    Shari Lipner MD, PhD
    Adam Lipworth MD
    Jason Maguire MD
    Mark Malek MD, MPH
    Jere Mammino DO
    Ricardo Mandojana MD
    Lynne Margesson MD
    Thomas J. Marrie MD
    Maydel Martinez MD
    Ralph Massey MD
    Patrick McCleskey MD
    Karen McKoy MD
    Thomas McMeekin MD
    Josette McMichael MD
    Somchai Meesiri MD
    Joseph F. Merola MD
    Mary Gail Mercurio MD
    Anis Miladi MD
    Larry E. Millikan MD
    Dan Milner Jr. MD
    Zaw Min MD
    Stephanie Montero
    Alastair Moore MD
    Keith Morley MD
    Dean Morrell MD
    Samuel Moschella MD
    Taimor Nawaz MD
    Vic Newcomer MD
    John Nguyen MD
    Matilda Nicholas MD
    Thomas P. Nigra MD
    Steven Oberlender MD, PhD
    Maria Teresa Ochoa MD
    Art Papier MD
    Lawrence Parish MD
    Tanner Parrent MD
    Mukesh Patel MD
    Lauren Patty-Daskivich MD
    David Peng MD, MPH
    Robert Penne MD
    Nitipong Permpalung MD
    Miriam Pomeranz MD
    Doug Powell MD
    Harold S. Rabinovitz MD
    Christopher J. Rapuano MD
    Sireesha Reddy MD
    Angela Restrepo MD, PhD
    Bertrand Richert MD, PhD
    J. Martin Rodriguez, MD, FACP
    Theodore Rosen MD
    Misha Rosenbach MD
    Scott Schiffman MD
    Robert H. Schosser MD
    Glynis A. Scott MD
    Carlos Seas MD, MSc
    Deniz Seçkin MD
    Daniel Sexton MD
    Paul K. Shitabata MD
    Tor Shwayder MD, FAAP, FAAD
    Elaine Siegfried MD
    Gene Sienkiewicz MD
    Christye Sisson
    Philip I. Song MD
    Mary J. Spencer MD, FAAP
    Lawrence B. Stack MD
    Sarah Stein MD
    William Van Stoecker MD
    Frances J. Storrs MD
    Erik J. Stratman MD
    Lindsay C. Strowd MD
    Erika Summers MD
    Belinda Tan MD, PhD
    Robert Tomsick MD
    Hensin Tsao MD, PhD
    Jenny Valverde MD
    Vishalakshi Viswanath MD
    Susan Voci MD
    Lisa Wallin ANP, FCCWS
    Douglas Walsh MD
    Ryan R. Walsh MD
    George Watt MD
    Clayton E. Wheeler MD
    Sally-Ann Whelan MS, NP, CWOCN
    Jan Willems MD, PhD
    James Henry Willig MD, MPH
    Karen Wiss MD
    Vivian Wong MD, PhD
    Sook-Bin Woo MS, DMD, MMSc
    Jamie Woodcock MD
    Stephen J. Xenias MD
    Lisa Zaba MD
    Vijay Zawar MD
    Bonnnie Zhang MD
    Carolyn Ziemer MD


Organizations

  • Am. Journal of Trop. Med & Hygiene
  • Armed Forces Pest Management Board
  • Blackwell Publishing
  • Bugwood Network
  • Centers For Disease Control and Prevention
  • Centro Internacional de Entrenamiento e Investigaciones Mèdicas (CIDEIM)
  • Dermatology Online Journal
  • East Carolina University (ECU), Division of Dermatology
  • International Atomic Energy Agency
  • Massachusetts Medical Society
  • Oxford University Press
  • Radiological Society of North America
  • Washington Hospital Center
  • Wikipedia
  • World Health Organization
ContentsSynopsisCodesLook ForDiagnostic PearlsDifferential Diagnosis & PitfallsBest TestsManagement PearlsTherapyDrug Reaction DataReferencesView all Images (8)
Toxoplasmosis
See also in: External and Internal Eye
Print
Other Resources UpToDate PubMed

Toxoplasmosis

See also in: External and Internal Eye
Print Images (8)
Other Resources UpToDate PubMed

Synopsis

Toxoplasmosis is a worldwide zoonosis caused by Toxoplasma gondii, an obligate intracellular protozoan parasite. Toxoplasma gondii exists in 3 morphologic forms: oocyst, tissue cyst (contains bradyzoites), and tachyzoite (the proliferative form). Felines are the definitive host. Mammals (herbivores and carnivores), birds, and reptiles can also be infected. Sexual reproduction takes place only in the feline intestinal tract, resulting in oocysts that are shed in stools.

Human infection may occur from the following:
  • Ingestion of oocysts in contaminated food or water
  • Ingestion of tissue cysts contained in undercooked meat (particularly pork, lamb, bear, and deer) or from tissue cysts in transplanted organs (kidney and heart)
  • Intake of tachyzoites (congenital infection and, rarely, from blood transfusions or laboratory accidents)
On entering the human gastrointestinal (GI) tract, T. gondii infects the gut epithelium and disseminates widely throughout the body, with a predilection for the brain, heart and skeletal muscles, and eyes. The replication of the tachyzoites causes host cell death, and the clinical symptoms and signs depend on the organs involved and the extent of infection and host immunity. Once an effective host immune response has occurred, tachyzoites are killed, while tissue cysts remain and are responsible for the chronic, latent, asymptomatic infection that ensues. This latent infection can be detected serologically. The tissue cysts have a predilection for the central nervous system (CNS), eye, and muscle and serve as a reservoir from which local or disseminated disease can develop if immunosuppression occurs. Reactivation disease usually presents as toxoplasma encephalitis or chorioretinitis.

The incidence of toxoplasmosis increases with increasing age but does not vary significantly by sex. The seroprevalence of antibodies to T. gondii in the United States is about 20%. Seroprevalence rates are much higher in Europe, Africa, and Central and South America.

Acute primary toxoplasmosis in the immunocompetent host most commonly causes an asymptomatic infection (80%-90%). Cervical lymphadenopathy, particularly of the posterior cervical nodes, without other associated signs or symptoms is the most common clinical manifestation. Other lymph node groups may also be involved. Enlarged nodes are usually smooth, firm, mobile, and nontender and do not suppurate. The lymphadenopathy resolves spontaneously over weeks to months. It has been estimated that up to 7% of clinically significant lymphadenopathies are caused by toxoplasmosis.

Very rarely a mononucleosis-like syndrome may occur with headache, fever, sore throat, lymphadenopathy, fatigue, myalgia, arthralgias, malaise, hepatosplenomegaly, macular erythematous rash (during the first week of illness), mild elevations in the serum transaminases, and the presence of atypical lymphocytes on the peripheral blood smear. Some patients may present with only a few of the above features. It is thought that less than 1% of mononucleosis-like syndromes are caused by acute toxoplasmosis. Very rarely, severe disseminated toxoplasmosis may occur in an apparently healthy adult. Depending on the specific organ involved, it may present as encephalitis, myocarditis, hepatitis, polymyositis, or pneumonitis.

Ocular toxoplasmosis can result from congenital infection or from reactivation of latent postnatally acquired infection and rarely develops during acute infection. Toxoplasma gondii is the most common cause of chorioretinitis in immunocompetent adults. The prevalence of ocular toxoplasmosis is unknown but has been estimated at 2% of seropositive patients. Relapse, even after therapy, particularly in the eye initially involved, is the rule. Patients may complain of blurry vision, scotoma, photophobia, redness, and excessive lacrimation. Atypical findings include eye pain, prominent retinal hemorrhage, and lack of retinal scarring on ophthalmologic examination. They warrant polymerase chain reaction (PCR) testing of the vitreous or aqueous fluid for toxoplasma DNA to confirm the diagnosis.

Pregnant Patient Considerations:
Acute T. gondii infection in pregnant women is usually asymptomatic. The most frequent clinical manifestation is regional lymphadenopathy. Acute maternal infection can result in transmission to the fetus. However, the risk of fetal transmission is not increased if maternal infection is symptomatic. With rare exceptions (infection within 3 months of conception or maternal immunosuppressed state), women previously infected with T. gondii, and therefore seropositive for anti-toxoplasma antibodies prior to pregnancy, are protected from transmitting the infection to their fetuses. HIV-infected women with latent toxoplasmosis may have reactivation of latent infection, which can result in fetal transmission. The incidence of fetal transmission is highest during second- and third-trimester maternal infection. Though less frequent, fetal transmission during first-trimester maternal infection more commonly results in severe illness in the newborn. See congenital toxoplasmosis.

Immunocompromised Patient Considerations:
Seronegative organ transplant recipients from a T. gondii-seropositive donor, seropositive hematopoietic stem cell transplant recipients, patients with AIDS, and those receiving corticosteroids are at risk for disease caused by reactivation of chronic latent T. gondii infection. Primary toxoplasmosis is very rare but can cause disseminated disease, which is frequently fatal. The most common presentation of reactivation of latent infection is toxoplasmic encephalitis and much less frequently chorioretinitis; other organ involvement (pneumonitis, myocarditis) occurs rarely. Manifestations of toxoplasmic encephalitis include focal neurological deficits (hemiparesis, speech abnormalities, altered mental status, movement disorders), seizures, headache, and fever.

Codes

ICD10CM:
B58.9 – Toxoplasmosis, unspecified

SNOMEDCT:
187192000 – Toxoplasmosis

Look For

Subscription Required

Diagnostic Pearls

Subscription Required

Differential Diagnosis & Pitfalls

Lymphadenopathy:
  • Epstein-Barr virus (EBV) mononucleosis – Monospot test is usually positive.
  • Acute cytomegalovirus (CMV) infection – Check for CMV IgM positivity in the serum and the presence of CMV DNA in the blood by PCR testing.
  • Acute HIV infection – Elicit exposure risk factors. Standard HIV testing (enzyme-linked immunosorbent assay; ELISA) may be negative at first but will become positive within a few weeks. Check an HIV viral load, which is always positive in this setting.
  • Lymphadenopathy without other associated symptoms – Think about lymphomalymphoma, and sample a lymph node (fine needle aspiration or excisional biopsy).
  • Cat-scratch diseaseBartonella henselae (and the putative agents Afipia felis and Bartonella clarridgeiae); serology can establish the diagnosis.
Ocular Toxoplasmosis:
  • Ocular toxoplasmosis may resemble the chorioretinitis of tuberculosis; check purified protein derivative (PPD) and chest X-ray.
  • Syphilis – Check serum RPR; other appropriate serologic tests (eg, cerebrospinal fluid [CSF] VDRL).
  • Toxocariasis – Chorioretinal scars not typically seen; check Toxocara ELISA.
  • Acute retinal necrosis (see herpes zoster ophthalmicus) – HSV/VZV PCR detection in aqueous.
  • Other causes of posterior uveitis.
In patients with atypical lesions or a poor response to anti-toxoplasma therapy, consider toxoplasma DNA detection by PCR in the vitreous or aqueous fluid.

Immunocompromised Patient Differential Diagnosis:
  • Primary CNS non-Hodgkin lymphoma of the brain is by far the most common entity in the differential diagnosis of toxoplasmic encephalitis. Patients virtually always have CD4 cell counts <50/mm3. Serology for toxoplasmosis is usually negative. CSF EBV DNA PCR detection is usually positive. Thallium-201 single proton emission CT (SPECT) scanning shows increased metabolic activity. A definitive diagnosis may require brain biopsy.
  • Tuberculoma (see tuberculosis)
  • Cryptococcoma (see cryptococcosis)

Best Tests

Subscription Required

Management Pearls

Subscription Required

Therapy

Subscription Required

Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

Subscription Required

References

Subscription Required

Last Updated: 02/04/2016
Copyright © 2018 VisualDx®. All rights reserved.
Toxoplasmosis
See also in: External and Internal Eye
Print 8 Images
View all Images (8)
(with subscription)
Toxoplasmosis (Immunocompetent) : Cervical lymphadenopathy, Most patients are asymptomatic
Clinical image of Toxoplasmosis
Copyright © 2018 VisualDx®. All rights reserved.