Cause:Toxoplasma gondii
Pathophys:Inflammation and scarring in brain, liver, spleen, heart, eye. Cysts are inert. Eye lesions probably are due to delayed hypersensitivity reactions. Congenital form somewhat different clinical pattern than acquired
Cats are primary hosts, usually transmitted via cat feces, contaminated water (Nejm 1982;307:666) or dust (Nejm 1979;300:695); also from poorly cooked meat 15-30% of US population have had, esp in wet hot areas
Immunosuppression can induce. Fetus very susceptible; 40% contract disease when mother gets primary infection between 2- and 6-mo gestation (Nejm 1974;290:110). Increased in AIDS as an opportunistic infection
Sx:
Acquired (Nejm 1979;300:695) (90%): fever, headache (85%), myalgia (60%), rash (20%)
Congenital: rash
Si:
Acquired: lymphadenopathy (85%), rash (20%), chorioretinitis
Congenital: chorioretinitis (100%), icterus, rash, hepatosplenomegaly, hydrops, hydrocephalus
Acquired: meningoencephalitis (50%), r/o lymphoma (Ann IM 1969;70:514); myocarditis
Lab:
CSF:Congenital: organisms on Wright's stain and grow in mice
Path:Intracellular blue with red cytoplasm; can look like intracellular "grapes" when multiplying in cell. Do brain bx in AIDS patients w meningoencephalitis if don't respond to pyrimethamine + clindamycin within 2 wk (Nejm 1993;329:995)
Serol:Indirect fluorescent antibody positive if >1:1000; comp-fix antibody and Sabin-Feldman dye test; IgM titers
Xray:
Acquired: CT of head shows focal encephalitis with enhancing rings (Nejm 1988;318:1439)
Congenital: In utero, cerebral calcifications and bony "white puffs"
Rx:
Congenital: prevent w screening titer at 1st ob visit, then q 1-mo toxo titers (if elevated but stable, no problem), and in exposed sero-neg pregnant women; abort if convert and fetal infection documented, eg, by amniocentesis PCR methods (Nejm 1994;331:695); or rx with spiramycin; or pyrimethamine + sulfa, which results in 13/15 healthy newborns, other 2 had only retinitis (France—Nejm 1988;318:271). Or screen newborns for IgM toxo titers; this detects 1 case/6000 infants in New England and subsequent rx allows prevention of future eye disease (Nejm 1994;330:1858)
Acquired: 1st choice pyrimethamine 25-100 mg/d or 2 mg/kg/d × 3 d then 1 mg/kg/d up to 25 mg + sulfadiazine 1-2 gm or 25-50 mg/kg qid × 3-4 wk; or pyrimethamine + clindamycin 1200 mg qid (Nejm 1993;329:995; Ann IM 1992;116:33), which is preferable in AIDS because 40% of such pts can't tolerate sulfa. Alternative is spiramycin 3-4 gm/kg or 50-100 mg/kg/d × 3-4 wk of eye involvement: steroid