Toxoplasmosis

Epidemiology

  • Toxoplasmosis is the most common cause of focal brain lesion in AIDS
  • Pulmonary toxoplasmosis is uncommon
  • Higher incidence of HIV-related Toxo in Western Europe, Africa than in North America (possibly due to dietary differences)
  • About 33% of T. Gondii Ab-positive HIV cases will develop CNS Toxo
  • Average CD4 at time of diagnosis of Toxo is 32

Physiology

  • Reactivation of chronic, latent infection

Diagnosis

  • Induced sputum: diagnosed no cases

FOB: BAL or TBB may reveal organism

Pleural fluid: may reveal organism

CXR/Chest CT patterns:
1) Diffuse bilateral interstitial/ coarse nodular infiltrates: indistinguishable from PCP
2) Pleural effusion: may be seen

T. Gondii Ab: present in 10-40% of HIV-positive patients in USA
-Positive in 11 of 12 reported cases in one series


Clinical Presentations

  • Interstitial Pneumonia (see [[ILD-Etiology]])

-Dyspnea:
-Fever:
-Dry cough:
-Extrapulmonary involvement: present in 7 of 12 reported cases in one series


Treatment

  • Pyrimethamine + Sulfadiazine: preferred treatment
  • Prevention: one study showed decreased incidence of pulmonary Toxo with Pyrimethamine + Dapsone prophylaxis in cases with positive T. Gondii Ab and CD4 >200

References

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