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- Obligate intracellular protozoan parasite Toxoplasma gondii
- Most common latent protozoan infection
- Usually dangerous only in pregnancy or in an immunocompromised patient
- Acute self-limited infection if immunocompetent
- Acute symptomatic or reactivated latent infection in immunocompromised persons
- Congenital toxoplasmosis (acute primary infection during pregnancy)
- Ocular toxoplasmosis
- The earlier fetal infection occurs, the more severe
- Risk of perinatal death is 5% if infected in 1st trimester
- Birth prevalence of congenital toxoplasmosis in the US: 10–100/100,000 live births
- Predominant sex: Male > Female
- In the US, 11% aged 6–49 years are seropositive.
- Age-adjusted prevalence in the US is 22.5%.
- Seroprevalence among women in the US is 15%.
- Immunocompromised states, including HIV infection with CD4 cell count <100/μL
- Primary infection during pregnancy; risk of transmitting infection to the fetus increases with gestational age at seroconversion, although transmission in the 1st trimester is associated with more severe consequences.
- Chronically infected pregnant women who are immunocompromised have an increased risk of congenital toxoplasmosis.
Human leukocyte antigen (HLA) DQ3 is a genetic marker of susceptibility in AIDS.
Prevention is important in seronegative pregnant women and immunodeficient patients:
- Avoid eating undercooked meat: Cook to 152°F (66°C) or freeze for 24 hours at ≤–12°C.
- Avoid drinking unfiltered water.
- Wash produce.
- Strict hand hygiene after touching soil.
- Wear gloves and wash hands after handling handling raw meat or cat litter.
- Avoid eating shellfish; (Toxoplasma cysts)
Transmission to humans:
- Ingestion of raw or undercooked meat, food, or water containing tissue cysts or oocytes; usually from soil contaminated with feline feces
- Transplacental to fetus from infected mother; risk of transmission is 30% on average
- Blood product transfusion and solid-organ transplantation
T. gondii, an obligate intracellular sporozoan
Commonly Associated Conditions
- Chorioretinitis; self-limiting, febrile lymphadenopathy; mononucleosislike illness
- A statistically significant association exists between schizophrenia and several infectious agents (including T. gondii); clinical implications are unclear (2).