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Questions and Answers
What is the most effective available therapeutic combination for treating toxoplasmosis?
What is the primary reason for using prednisone in toxoplasmosis treatment?
What should be avoided when handling raw meat to prevent toxoplasmosis?
What is the consequence of using oral corticosteroids without antibiotic coverage in toxoplasmosis treatment?
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When should antiparasitic agents be stopped in toxoplasmosis treatment?
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What is a key aspect of preventing toxoplasmosis?
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What is the maximum diameter of tissue cysts in Toxoplasmosis?
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In which tissues are cysts preferentially located in the clinical phase of Toxoplasmosis?
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What is the outcome for the majority of bradyzoites in the brain and muscles of immunocompetent patients?
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What is the characteristic of bradyzoites in terms of immune response?
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What is the likely outcome for immunocompromised patients with Toxoplasmosis?
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What is the usual cause of Retinochoroiditis in Toxoplasmosis?
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What is a characteristic of T-lymphocyte levels in acute acquired Toxoplasmosis infection?
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What is the characteristic appearance of retinochoroiditis lesions in ocular toxoplasmosis?
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What is a hypothesis related to the inflammatory process of ocular Toxoplasmosis?
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What is the primary symptom of ocular toxoplasmosis?
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Which of the following is used to detect T. gondii organisms in blood or body fluids?
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What is the purpose of administering leucovorin along with pyrimethamine in the treatment of toxoplasmosis?
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What is the primary goal of treatment in ocular toxoplasmosis?
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What is the recommended timing for performing amniocentesis in suspected congenital toxoplasmosis?
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Which of the following is a common neurological sequela of ocular toxoplasmosis?
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What is the purpose of performing a lumbar puncture in the diagnosis of toxoplasmosis?
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Study Notes
Ocular Toxoplasmosis
- Patients develop retinochoroiditis, characterized by:
- Focal necrotizing retinitis
- Yellowish-white, elevated cotton patch with indistinct margins
- Lesions may occur in small clusters
- Congenital disease usually bilateral, acquired disease usually unilateral
- Symptoms include:
- Impaired vision (sudden or gradual)
- Blurred vision
- Scotoma
- Pain
- Photophobia
- Floaters
- Red eye
- Metamorphopsia
Diagnosis
- Direct detection of T. gondii organisms in blood, body fluids, or tissue using PCR
- Indirect detection of IgG using ELISA test (within 2 weeks of infection)
- Diagnostic procedures:
- Lumbar puncture (after imaging to identify evidence of increased intracranial pressure)
- Brain biopsy
- Lymph node biopsy
- Amniocentesis (at 20-24 weeks' gestation if congenital disease is suggested)
Treatment
- Medications primarily target the tachyzoite form of T. gondii
- Pyrimethamine is the most effective agent
- Leucovorin (folinic acid) should be administered concomitantly to prevent bone marrow suppression
- Combination therapy with a second drug (e.g., sulfadiazine, clindamycin) is recommended
- Prednisone is used to limit inflammatory damage
- Antiparasitic agents should be stopped only after steroids have been stopped
Prevention
- Avoid eating raw meat, unpasteurized milk, and uncooked eggs
- Avoid eating oysters, clams, and mussels
- Wash hands after touching raw meat
- Wear gloves when gardening or handling soil and wash hands afterwards
- Wash fruits and vegetables
- Avoid contact with cat feces
Tissue Cysts
- Up to 60μm in diameter, containing up to 60,000 organisms
- Preferentially located in neural and muscle tissues
- Rupture periodically, releasing bradyzoites
- Host's immune response destroys bradyzoites, but some remain in the brain and muscles indefinitely
- Cause recurrent disease in immunocompromised patients or retinochoroiditis in congenitally infected older children
Changes in T-Lymphocyte Levels
- Alterations in subpopulations of T lymphocytes during acute acquired T. gondii infection
- Correlated with disease syndromes, but not with disease outcome
- Patients with prolonged fever and malaise may have lymphocytosis, increased suppressor T-cell counts, and a decreased helper-to-suppressor T-cell ratio
Retinochoroiditis
- Results from reactivation of congenital infection or acute infection
- 5 hypotheses related to the inflammatory process of ocular toxoplasmosis:
- Infection and inflammatory response after spontaneous cyst rupture
- Parasitic toxic mediators released from T. gondii
- Lytic effect of inflammatory mediators
- Delayed-type hypersensitivity reaction to antigens of T. gondii
- Cell-mediated immunity against retinal antigens
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Description
This quiz covers the symptoms and characteristics of ocular toxoplasmosis, including retinochoroiditis, impaired vision, and more. Test your knowledge of this eye disease.
