How is CNS toxoplasmosis in HIV infection diagnosed?

Updated: Jul 11, 2017
  • Author: Gulshan Uppal, MD; Chief Editor: Niranjan N Singh, MBBS, MD, DM, FAHS, FAANEM  more...
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Definitive diagnosis of CNS toxoplasmosis requires the following [1] :

  • Compatible clinical findings

  • Identification of one or more mass lesions by CT, MRI, or other radiographic testing

  • Detection of T gondii in a clinical sample

Detection of T gondii DNA on polymerase chain reaction (PCR) testing of cerebrospinal fluid (CSF) samples may facilitate the diagnosis and follow-up of toxoplasmosis in patients with AIDS. [5] In a study using the B1 gene, rapid PCR showed a sensitivity of 83.3% and specificity of 95.7%. [6]

CSF findings may also include elevated protein and variable glucose and WBC counts. The presence of Epstein-Barr virus DNA in the CSF favors the diagnosis of lymphoma.

Lumbar puncture may be contraindicated because of increased intracranial pressure, however. For many clinicians, therefore, CNS toxoplasmosis is an empiric diagnosis that relies on clinical and radiographic improvement in response to specific anti-T gondii therapy. In patients who fail to respond to specific therapy, brain biopsy can be used to secure a clinical sample for testing. [1]

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