Toxoplasma Retinitis

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Clinical Presentation

  • active:
    • Solitary inflammatory lesion near an old pigmented scar (“satellite lesion”)
    • Ill-defined white lesions with pronounced vitritis (“headlight in fog”)
    • White spots along arterioles (Kyrieleis Plaques)
    • Possible spill-over with granulomatous anterior uveitis
  • inactive:
    • Chorioretinal scars at the posterior pole (in the macular region in congenitally acquired disease)

Work-up

  • Slit-lamp exam
  • Serology: Toxoplasma IgG/IgM
  • +/- anterior chamber tap (PCR and Goldmann-Witmer coefficient) in case of unclear clinical presentation
  • Imaging in AIDS patients to rule out intracranial toxoplasmosis

Treatment

  • Indications for Treatment:
    • Lesion near the fovea or optic disc
    • Larger or multiple active lesions, pronounced vitritis
    • Immunosuppression
    • Others: Visual reduction, pregnancy, congenital toxoplasmosis
    • Extramacular lesions may be observed without treatment
  • Note: No universally accepted treatment regimen!
  • “Classic” Therapy
    • Pyrimethamine (Daraprim) 100mg/day for the first 2 days, then 25-50mg/day
    • Sulfadiazine: Loading dose of 2g, then 4x 1g
    • Leucovorin (Folinic acid) 15mg 2x/week
  • Alternatives:
    • Clindamycin (e.g., 600mg 3x daily); +/- in addition to Sulfadiazine/Pyrimethamine or instead of Pyrimethamine or Sulfadiazine
    • Trimethoprim/Sulfamethoxazole (Co-Trimoxazole = Bactrim forte, 160mg/800mg) 2x daily
    • Azithromycin (1g on the first day, then 500mg daily)
  • Duration of Therapy: at least 4-6 weeks
  • Laboratory: Complete blood count, liver and kidney function every 1-2 weeks by general practitioner / clinic
  • Steroids:
    • In case of threatened vision; Caution: in immunosuppressed patients
    • Prednisone initially 0.5-1mg/kg body weight
    • Only in conjunction with antimicrobial therapy; consider initiating steroids 24-48h after the start of antimicrobial therapy (controversial)

Prophylaxis

  • Bactrim Forte 3x/week for at least 1 year, possibly longer (e.g., in immunosuppression)

Congenital Toxoplasmosis

  • Risk of transplacental infection increases during pregnancy; severity of congenital infection decreases over the course of pregnancy
  • Retinochoroiditis in >75%
  • Fundus examination perinatally with maternal seroconversion, then
    • In asymptomatic infection (serology, no clinical symptoms):
      • Fundus examination after 3 and 12 months, then annually until the age of 10
    • In symptomatic congenital toxoplasmosis :
      • Fundus examination after (1), 3, 6, 10, 15-18, and 24 months, then annually until the age of 10 (without eye involvement) or 20 years (with eye involvement)

Sources