Toxoplasmosis - Toxoplasma gondii
also see TORCH

Etiology: Intracellular protozoan parasite

Epidemiology: Incidence 1/1000 to 1/10000 live births; Source: Feces of newly infected cat, undercooked pork

Pathogenesis: Mother infected during pregnacy, worst in 1st trimester

Presentation:

Diagnosis:

Treatment: Interrupts acute disease

Toxoplasma infection can occur by ingestion of oocysts following the handling of contaminated soil or cat litter or the consumption of contaminated water or food sources (such as unwashed garden vegetables). The oocysts in stool become infectious 24 hours or more after they are shed by a cat. During a primary infection, a cat can shed millions of oocysts daily for 1 to 3 weeks. The oocysts are very hardy and may remain infectious for more than 1 year (especially in warm, humid environments). Transmission also can occur by ingestion of tissue cysts present in undercooked meat (especially pork, mutton, and beef).

Diagnostic testing is the best means to distinguish CMV infection from toxoplasmosis because many of their clinical features overlap. Toxoplasmosis is more apt to present with chorioretinitis and scattered cerebral calcifications; CMV infection more frequently is associated with periventricular calcifications. CMV is diagnosed best by culture of the infantís urine in the first 3 to 4 weeks of life. Serologic testing of maternal and infant sera is the best method for diagnosing congenital toxoplasmosis, but it is less useful in identifying CMV infection.
 

References:
CHLA Board Review 2005
American Academy of Pediatrics. Toxoplasma gondii infections. In: Pickering LK, ed. 2000 Red Book: Report of the Committee on Infectious Diseases. 25th ed. Elk Grove Village, Ill: American Academy of Pediatrics; 2000:583-586
Boyer KM, Remington JS, McLeod RL. Toxoplasmosis. In: Feigin RD, Cherry JD, eds. Textbook of Pediatric Infectious Diseases. 4th ed. Philadelphia, Pa: WB Saunders Co; 1998:2473-2490
Lynfield R, Guerina NG. Toxoplasmosis. Pediatr Rev. 1997;18:75-83
Remington JS, McLeod R, Desmonts G. Toxoplasmosis. In: Remington JS, Klein JO, eds. Infectious Diseases of the Fetus & Newborn Infant. 4th ed. Philadelphia, Pa: WB Saunders Co; 1995:140-247