Toxoplasmic Encephalitis

Prevention of Exposure
(1) HIV-infected persons should be tested for IgG antibody to Toxoplasma soon after the diagnosis of HIV infection to detect latent infection with Toxoplasma gondii (BIII).

(2) All HIV-infected persons, but particularly those who lack IgG antibody to Toxoplasma, should be counseled about the various sources of toxoplasmic infection. They should be advised not to eat raw or undercooked meat, particularly undercooked pork, lamb, or venison (BIII). Specifically, meat should be cooked to an internal temperature of 150 F^o (65.5 C^o); meat cooked until it is no longer pink inside generally has an internal temperature of 165 F^o (73.8 C^o) and therefore satisfies this requirement. HIV-infected persons should wash their hands after contact with raw meat and after gardening or other contact with soil; in addition, they should wash fruits and vegetables well before eating them raw (BIII). If the patient owns a cat, the litter box should be changed daily, preferably by an HIV-negative, nonpregnant person; alternatively, the patient should wash the hands thoroughly after changing the litter box (BIII). Patients should be encouraged to keep their cats inside and not to adopt or handle stray cats (BIII). Cats should be fed only canned or dried commercial food or well-cooked table food, not raw or undercooked meats (BIII). Patients need not be advised to part with their cats or to have their cats tested for toxoplasmosis (EII).

Prevention of Disease

Initiation of Primary Prophylaxis
(3) Toxoplasma-seropositive patients who have a CD4+ T-lymphocyte count of <100/uL should be administered prophylaxis against toxoplasmic encephalitis (TE) (AII) (20). The daily doses of TMP-SMZ recommended as the preferred regimens for PCP prophylaxis appear to be effective against TE as well and are therefore recommended (AII) (20). If patients cannot tolerate TMP-SMZ, a regimen that can be recommended as an alternative which is also effective against PCP is dapsone-pyrimethamine (AI) (24, 25). Atovaquone with or without pyrimethamine may be considered (CIII). Prophylactic monotherapy with dapsone, pyrimethamine, azithromycin, or clarithromycin cannot be recommended on the basis of current data (DII). Aerosolized pentamidine does not afford protection against TE and is not recommended for this purpose (EI) (16, 20).

(4) Toxoplasma-seronegative persons who are not taking a PCP prophylactic regimen known to be active against TE should be retested for IgG antibody to Toxoplasma when their CD4+ T-lymphocyte count declines below 100/uL to determine whether they have seroconverted and are therefore at risk for TE (CIII). Patients who have seroconverted should be administered prophylaxis for TE as described above (AII).

Discontinuation of Primary Prophylaxis
(5) Limited data suggest that discontinuation of prophylaxis in patients whose CD4+ T-lymphocyte counts increase to >100 cells/uL in response to HAART is associated with a low risk of TE. However, the numbers of patients who have been evaluated are insufficient to recommend routine discontinuation of prophylaxis in such patients. Persons whose CD4+ T-lymphocyte count remains <200 cells/uL or have a history of PCP or oropharyngeal candidiasis still require prophylaxis against PCP, as noted above.

Prevention of Recurrence
(6) Patients who have had TE should be administered lifelong suppressive therapy (i.e., secondary prophylaxis or chronic maintenance therapy) with drugs active against Toxoplasma to prevent relapse (AI) (34, 35). The combination of pyrimethamine plus sulfadiazine and leucovorin is highly effective for this purpose (AI) (34, 35). A commonly used regimen for patients who cannot tolerate sulfa drugs is pyrimethamine plus clindamycin (BI); however, only the combination of pyrimethamine plus sulfadiazine appears to provide protection against PCP as well (AII).

Discontinuation of Secondary Prophylaxis (chronic maintenance therapy)
(7) The numbers of patients who have stopped maintenance therapy after responding to HAART is insufficient to warrant recommending discontinuation of maintenance therapy at this time.

Notes

Pediatric Note
(8) TMP-SMZ, when administered for PCP prophylaxis, also provides prophylaxis against toxoplasmosis. Children aged >12 months who qualify for PCP prophylaxis and who are receiving an agent other than TMP-SMZ or atovaquone should have serologic testing for Toxoplasma antibody (BIII), because other drugs for PCP prophylaxis may not be effective against Toxoplasma. If seropositive for Toxoplasma, children should be administered prophylaxis for both PCP and toxoplasmosis (i.e., dapsone plus pyrimethamine) (BIII) or atovaquone (CIII).

Notes Regarding Pregnancy
(9) TMP-SMZ can be administered for prophylaxis against TE as described for PCP (AIII). However, because of the low incidence of TE during pregnancy and the possible risk associated with pyrimethamine treatment, chemoprophylaxis with pyrimethamine-containing regimens can reasonably be deferred until after pregnancy (CIII). For prophylaxis against recurrent TE, the health-care provider and clinician should be well informed about the benefit of lifelong therapy and the concerns about teratogenicity of pyrimethamine. Most clinicians favor lifelong therapy for the mother, given the high likelihood that disease will recur promptly if therapy is stopped (AIII).

(10) In rare cases, HIV-infected pregnant women who have serologic evidence of remote toxoplasmic infection have transmitted Toxoplasma to the fetus in utero. Pregnant HIV-infected women who have evidence of primary toxoplasmic infection or active toxoplasmosis (including TE) should be evaluated and managed during pregnancy in consultation with appropriate specialists (CIII). Infants born to women who have serologic evidence of infections with HIV and Toxoplasma should be evaluated for congenital toxoplasmosis (CIII).

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