Toxoplasmosis is a protozoan parasite that spreads through food or water contaminated with oocysts, infected meat, or contact with oocysts from feline faeces.
Acute infection is usually asymptomatic, and once acquired, parasites remain in human tissues lifelong.
Symptomatic disease can be seen in patients who are immunocompromised with re-activation of latent infection or with acquisition of new infection.
Symptomatic eye disease can be seen in both patients who are immunocompromised and patients who are immunocompetent.
Primary infection during pregnancy is often asymptomatic in the mother, but can result in congenital disease in the fetus.
Toxoplasmosis is caused by the protozoan parasite Toxoplasma gondii. Cats are the definitive hosts for the parasite and can excrete millions of oocysts that survive in the environment for months. Humans are intermediate hosts, and become infected by ingesting uncooked meat infected with tissue cysts (bradyzoites), by ingestion of other food or water contaminated with oocysts, or by transplacental spread of tachyzoites. Once bradyzoites or oocysts are ingested, or tachyzoites have spread through the placenta to a fetus, T gondii rapidly travels to tissues and organs where it encysts and remains permanently. Infection in humans is lifelong and often asymptomatic, unless a patient becomes immunosuppressed.
History and exam
Sarah Hochman, MD
Department of Medicine
Division of Infectious Diseases and Immunology
New York University School of Medicine
SH declares that she has no competing interests.
Kami Kim, MD
Professor of Medicine (Infectious Diseases) and Microbiology and Immunology
Albert Einstein College of Medicine
KK is on the advisory board for the Sanford Guide for Antibiotic Therapy. KK is the author of a reference cited in this topic.
Fabrizio Bruschi, MD
Professor of Parasitology
University of Pisa
School of Medicine
FB declares that he has no competing interests.
Srikrishna Nagri, MD
SN declares that he has no competing interests.
George Y. Wu, MD, PhD
Professor of Medicine
University of Connecticut Health Center
GYW is on the medical advisory boards of the following: Gilead Sciences, Bristol-Myers Squibb, AbbVie, and Intercept.
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