Toxoplasma encephalitis in an HIV-infected patient on highly active antiretroviral therapy despite sustained immune response

Abstract

Toxoplasma encephalitis (TE) is usually diagnosed in advanced stages of HIV infection when the CD4+ count is <100-200 cells/µl. A 55-year-old woman with HIV/AIDS, well controlled on antiretroviral therapy (ART), CD4+ count in the 300 cells/μl range for >1 year presented with acute onset of headache, nausea and vomiting. She had been on her current ART regimen consisting of raltegravir, co-formulated emtricitabine/tenofovir and etravirine for three years and had been off Pneumocystis prophylaxis for 10 months (trimethoprim-sulfamethoxazole). Brain MRI showed multiple ring-enhancing, supratentorial and infra-tentorial parenchymal lesions suspicious for metastases. She had no other evidence of metastatic disease in her body. The possibilities of TE and primary CNS lymphoma were considered but deemed unlikely given the high CD4+ count. A brain biopsy demonstrated Toxoplasma tachyzoites. There was no evidence of lymphoma or carcinoma. Anti-toxoplasma treatment yielded good initial clinical and radiographic responses. While on TE maintenance therapy, she developed similar symptoms. Repeat MRI showed progression of lesions. Further work-up including CSF Epstein-Barr virus PCR and SPECT Th 201 imaging was not conclusive for CNS lymphoma. The patient's clinical condition deteriorated and she died. We postulate that functional immunological dysfunction is a possible mechanism by which our patient developed TE despite demonstrating sustained immune response on ART.

Toxoplasma gondiiInfection in Pregnant Women: A Seroprevalence and Case-Control Study in Eastern China

“…Humans become infected by ingesting food or water contaminated with oocysts shed by cats; by eating undercooked or raw meat containing tissue cysts; or congenitally by transplacental transmission of tachyzoites [ 1 , 4 ]. Most infections are asymptomatic but in some individuals, especially if immunocompromised, the parasite can become widely disseminated causing severe clinical signs including encephalitis [ 5 ]. Primary infection during pregnancy can result in severe damage to the fetus manifested as mental retardation, seizures, blindness, or even death [ 6 ].…”

Extensive brain masses and cavitary lung lesions associated with toxoplasmosis and acquired immunodeficiency syndrome

“…The disease is usually seen when the CD4 cell count falls below 100 cells/ml (without prophylaxis), but can occur at higher CD4 cell counts, as in our patient. 3 Typically, 90% of patients have CD4 cell counts less than 200 cells/ml, and 75% have CD4 cell counts less than 100 cells/ml at the time of clinical presentation. Per United States guidelines, prophylaxis for toxoplasmosis in the setting of HIV is not recommended until the CD4 cell count is below 100 cells/ml, in contrast to the European guidelines where prophylaxis is recommended when the CD4 cell count falls below 200 cells/ml.…”

Harmonizing the CD4 Threshold for Initiating Toxoplasmosis Prophylaxis in Human Immunodeficiency Virus

“…In contrast to the American guidelines, the European guidelines [6] favor starting toxoplasmosis prophylaxis when the CD4 count falls below 200 cells/μL (Table 2). Some observations support the possibility of extensive cerebral toxoplasmosis at higher CD4 counts (above 100 cells/μL) either in newly diagnosed toxoplasma seropositive HIV patients or those already established on antiretroviral therapy [7,8]. Decisions on installation and discontinuation in these situations have to be taken individually.…”