Infectious Systemic Diseases

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Bacterial Blight - TB & Syphilis Eyes

  • Ocular Tuberculosis (TB):
    • Most common: Posterior uveitis (choroiditis, retinal vasculitis).
    • Choroidal tubercles: Creamy-yellow, deep lesions; may be single or multiple.
    • Eales disease: Peripheral retinal periphlebitis, often bilateral; associated with tuberculoprotein hypersensitivity.
    • Phlyctenular keratoconjunctivitis: Type IV hypersensitivity reaction.
    • Treatment: Standard Anti-Tubercular Therapy (ATT) + Corticosteroids (for inflammation).
  • Ocular Syphilis ("The Great Imitator"):
    • Most common: Uveitis (anterior, intermediate, posterior, or panuveitis).
    • Congenital: "Salt & pepper" fundus, interstitial keratitis (Hutchinson's triad component).
    • Neurosyphilis: Argyll Robertson pupil.
    • Acquired: Interstitial keratitis, chorioretinitis, optic neuritis.
    • Treatment: Penicillin (dosage varies by stage and neurosyphilis presence). Choroidal tubercle in ocular TB

⭐ Argyll Robertson pupil (ARP) in neurosyphilis: Characterized by Light-Near Dissociation. 📌 Mnemonic: ARP - Accommodation Reflex Present, Pupillary (Light) Reflex Absent ("Prostitute's Pupil" - accommodates but doesn't react).

Viral Visions - HIV & Herpes Hits

  • HIV/AIDS:

    • CMV Retinitis:

      • Most common opportunistic ocular infection. CD4 < 50 cells/µL (high risk), < 100 (moderate risk).
      • Fundus: "Cottage cheese & ketchup" or "pizza pie" appearance (hemorrhages, yellow-white infiltrates).
      • Progresses to retinal necrosis, detachment if untreated.
    • HIV Retinopathy: Non-infectious microvasculopathy. Cotton wool spots, retinal hemorrhages. Common.

    • Others: Kaposi sarcoma (eyelid/conjunctiva), Molluscum contagiosum, increased HZO risk.

  • Herpes Viruses:

    • HSV: Keratitis (dendritic ulcer 📌 pathognomonic), uveitis, Acute Retinal Necrosis (ARN).
    • VZV (HZO): Hutchinson's sign 📌 (vesicles on nose tip/side) strongly predicts ocular involvement. Keratitis, uveitis, neuralgia.

⭐ CMV retinitis is the most common opportunistic ocular infection in AIDS, typically occurring when CD4 count < 50 cells/µL.

Fungal Focus - Mucor & Candida Chaos

  • Mucormycosis (Zygomycosis)
    • Risks: Diabetes (esp. DKA), immunosuppression, deferoxamine therapy, trauma.
    • Key Presentation: Rhino-orbital-cerebral mucormycosis (ROCM) is most common; look for black necrotic eschar (nasal/palatal), proptosis, ophthalmoplegia, facial pain/numbness, vision loss.
    • Microscopy: Broad, non-septate (aseptate) hyphae with wide-angle (often 90°) branching.
    • Management: Urgent surgical debridement + systemic IV Amphotericin B (liposomal preferred). Rhino-orbital mucormycosis with black eschar
  • Candida Infections
    • Risks: IV drug use, indwelling catheters, TPN, broad-spectrum antibiotics, immunosuppression, recent major surgery.
    • Ocular: Endogenous endophthalmitis; chorioretinitis presenting as fluffy, white, deep retinal or subretinal lesions (“cotton ball” opacities), often with vitritis.
    • Management: Systemic antifungals (e.g., Fluconazole, Voriconazole); intravitreal antifungals (Amphotericin B or Voriconazole) for significant vitritis/endophthalmitis.

⭐ Rhino-orbital-cerebral mucormycosis (ROCM) is an aggressive, life-threatening fungal infection often seen in diabetic ketoacidosis (DKA) patients, characterized by black necrotic eschar in the nasal cavity or palate and rapid progression if untreated.

Parasite Plight - Toxo & Cystic Curses

  • Ocular Toxoplasmosis: Toxoplasma gondii infection.
    • Key: Necrotizing chorioretinitis.
      • Active: "Headlight in fog" (vitritis, fluffy lesion).
      • Inactive: Pigmented scar; satellite lesions common.
    • Congenital (common): 📌 Sabin's triad (chorioretinitis, hydrocephalus, intracranial calcifications).
    • Diagnosis: Clinical; serology (IgG/IgM), PCR (aqueous/vitreous).
    • Rx: Triple therapy (Pyrimethamine + Sulfadiazine + Corticosteroids).
  • Ocular Cysticercosis: Taenia solium larvae (Cysticercus cellulosae).
    • Sites: Subretinal (most common), vitreous, anterior chamber, orbit.
    • Intraocular: Translucent cyst ± visible scolex.
    • Orbital: Proptosis, diplopia, myositis.
    • Diagnosis: Clinical, B-scan, CT/MRI (co-existing neurocysticercosis).
    • Rx: Surgery (intraocular); Albendazole + steroids (orbital/adjunct). Ocular Toxoplasmosis: Headlight in Fog

⭐ In ocular toxoplasmosis, reactivation often occurs at the border of an old pigmented scar, leading to a satellite lesion.

High‑Yield Points - ⚡ Biggest Takeaways

  • Tuberculosis commonly causes choroidal tubercles and uveitis; Eales disease is a sequela.
  • Leprosy features madarosis, lagophthalmos, corneal anesthesia, and iris pearls.
  • Syphilis ("great masquerader") can cause interstitial keratitis (congenital) and Argyll Robertson pupil.
  • CMV retinitis ("pizza pie" appearance) is key in AIDS (CD4 <50).
  • Toxoplasmosis presents as focal necrotizing retinochoroiditis ("headlight in fog").
  • Herpes Zoster Ophthalmicus shows Hutchinson's sign, indicating higher risk of ocular involvement.
  • Dengue fever can lead to maculopathy and retinal hemorrhages.

Practice Questions: Infectious Systemic Diseases

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A child presents with a fever and a rash. Urine examination showed cells with owl's eye appearance. What is the most likely diagnosis?

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Flashcards: Infectious Systemic Diseases

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Loss of normal patten, and neovascularization are seen in _____ signs of anterior uveitis

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Loss of normal patten, and neovascularization are seen in _____ signs of anterior uveitis

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