SIGNS AND SYMPTOMS
The systemic symptoms found in congenital toxoplasmosis consist of convulsions, calcification of the arterioles and choreoretinitis. In adults, toxoplasmosis is often contracted without sickness. A small percentage of individuals encounter self-limiting, flu-like symptoms at the time of inoculation.
Toxoplasma exists in humans in two forms: (1) actively motile tachyzoites and (2) encysted Toxoplasma gondii called brachyzoites. The oocysts that contain the organisms which produce infection are excreted in fecal material and may lie dormant in the soil until ingested by other animals, resulting in infection.
Human infection may occur from ingestion of contaminated or undercooked meat and dairy products, direct or indirect ingestion of cat feces and transplacental transmission from an infected mother to the fetus. Toxoplasmosis can only be transmitted to a fetus during maternal parastemia. Congenital toxoplasmosis accounts for the majority of cases encountered in clinical practice.
In most cases, the body is primed for infection or toxoplasmosis reactivation by an immune system failure. This may occur following contraction of human immunodeficiency syndrome (HIV) or with medical immunosupression following organ transplantation.
The inflammatory fundus lesions are composed of mononuclear cells, with a liberation of lymphocytes, macrophages, epithelioid and plasma cells. The resulting retinal vasculitis contributes to the breakdown of the blood-retinal barrier and leads to a compromise in retinal function, with subsequent destruction and thickening.
Alternative antibiotic treatments include: (1) clindamycin, 300mg, PO QID used with sulfadiazine, for four to six weeks, (2) tetracycline, 2g loading then 250mg PO QID and sulfadiazine for four to six weeks, or (3) trimethoprim/sulfamethoxazole 160/800mg, one tablet PO BID, with or without clindamycin or prednisone, for the same duration.
In otherwise normal individuals, after beginning antibiotic therapy, add oral steroids at a dose of 20 to 80mg PO daily for four to six weeks. Periocular steroids are never indicated. Oral steroids without systemic antibiotics are expressly contraindicated.
Manage the anterior ocular inflammation with a cycloplegic that is appropriate for the disease's severity and a topical steroid Q2H/QID.
Systemic laboratory testing is indicated in active cases. The Sabin-Feldman methylene blue dye test (for Toxoplasma gondii), Serum antitoxoplasma antibody titer (for Toxoplasma gondii), Fluorescent Treponemal Antibody absorption test (for syphilis), purified protein derivative (for tuberculosis), chest x-ray (for sarcoid and TB), Toxocara Enzyme Linked Immunofluorescent Assay (for Toxocara canis) and Human Immunodefeciency Virus titer (for HIV) are among the important tests to order.
Other reports in this section
Eyelids & Eyelashes | Conjunctiva & Sclera | Cornea
Uvea | Vitreous & Retina | Optic Nerve & Brain | Oculosystemic Disease
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