Early Aqueous Humor Analysis in Patients with Human Ocular Toxoplasmosis

Garweg, Justus G.; Jacquier, P; Boehnke, Matthias

doi:10.1128/jcm.38.3.996-1001.2000

Cited by 59 publications

(18 citation statements)

References 55 publications

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“…However, sampling of this ocular medium is justified only in severe atypical or complicated cases. Using aqueous humour samples, the sensitivity is lower, lying below 25% for immunocompetent individuals (Table 1) (10,17,38–42). Given that the PCR‐method per se is highly sensitive and specific, this finding suggests that when the clinical symptoms are first manifested, it is the host's immune response rather than parasitic activity which drives the inflammatory response that is set in train to neutralize the pathogen.…”

Section: Parasitic Factorsmentioning

confidence: 99%

Determinants of immunodiagnostic success in human ocular toxoplasmosis

Garweg

2005

Parasite Immunology

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Ocular toxoplasmosis is a local manifestation of systemic infection in which Toxoplasma spreads into the eye, affecting mainly the posterior segment of the eye. Reactivation of the initial retinal condition presumably results from the rupture of quiescent parasitic cysts lying adjacent to pre-existing scars and may secondarily involve the choroid (leading to retinochoroiditis). Although the molecular mechanisms underlying host-parasite interaction are largely unknown, toxoplasmic retinochoroiditis usually remains a local event, and does not necessarily evoke a detectable systemic immune response. Local immunotolerance mechanisms may likewise confound attempts to confirm the clinical diagnosis by serology. Aqueous humour may be analysed for the presence of parasite DNA or of specific antibodies, but the DNA burden therein is low, and a more definite confirmation would require risky puncturing of the vitreous. Laboratory confirmation of the diagnosis is also frustrated by marked individual differences in the time elapsing between the onset of clinical symptoms and the activation of specific antibody production, resulting in a high proportion of false negative results. Whether a delay in the onset of local specific antibody production reflects immunotolerance in cases of congenital - but not obviously in those of acquired - infection remains an open question, but it could account for a relatively low confirmation rate in laboratory tests for local antibody production. Against this background, current diagnostic strategies need to be re-evaluated with a view to future improvements.

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Section: Parasitic Factorsmentioning

confidence: 99%

Determinants of immunodiagnostic success in human ocular toxoplasmosis

Garweg

2005

Parasite Immunology

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“…Historically, the use of PCR by itself for the diagnosis of ocular toxoplasmosis has lower or similar sensitivity to that of local antibody detection. 22 , 33 – 35 This may account for the relatively low number of patients with uveitis found positive for T. gondii ( n = 1) among our sample set.…”

Section: Discussionmentioning

confidence: 91%

Rapid Detection and Identification of Uveitis Pathogens by Qualitative Multiplex Real-Time PCR

Bispo

Davoudi

Sahm

et al. 2018

Invest. Ophthalmol. Vis. Sci.

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PurposeInfectious uveitis is a serious sight-threatening infection commonly caused by herpesviruses and Toxoplasma gondii. Etiologic diagnosis based on the clinical evaluation is often challenging. We developed and validated a multiplex real-time PCR assay coupled with high-resolution melting (HRM) for rapid detection and identification of herpes simplex viruses 1 and 2 (HSV-1 and HSV-2), varicella-zoster virus (VZV), cytomegalovirus (CMV), and T. gondii.MethodsThe assay was designed to target pathogen genome regions that yield products with distinct melting temperatures. Analytical specificity, sensitivity, and precision of HRM identification were determined. Clinical validation was performed by testing 108 intraocular fluids collected from eyes suffering with infectious uveitis (n = 30) and controls (n = 78).ResultsA nonoverlapping high-precision profile for each pathogen was generated following HRM (coefficient of variation 0%). The assay was highly sensitive, with a limit of detection of 20 genome copies for herpesviruses and 200 genome copies for T. gondii. The intra- and interassay variability of cycle threshold (Ct) measurement was ≤4% and ≤6%, respectively. Thirteen intraocular specimens collected from suspected cases of infectious uveitis were positive (mean Ct values varied from 19.4 to 27.7). Melting profiles of positive cases were consistent with HSV-2 (n = 5), VZV (n = 5), CMV (n = 2), and T. gondii (n = 1). Amplicon identities were confirmed by sequencing. Control intraocular samples from patients without a clinical diagnosis of infectious uveitis were all negative.ConclusionsThis assay allows rapid, sensitive, and reliable detection and identification of the most common known causes of infectious uveitis, making early pathogen information-based intervention possible.

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“…However, high rate of false-positive results due to the persistence of antibodies, decreases its utility as a diagnostic marker for recent ocular toxoplasmosis. In patients with reactivated ocular toxoplasmosis, it is not useful as T. gondii-specific IgM antibodies are either absent or present in very low quantity [79]. Saliva samples have also been tested for the detection of specific antibodies for the diagnosis of toxoplasma encephalitis in immunocompromised individuals, but it may play a limited role in ocular toxoplasmosis [74].…”

Section: Advances In Common Eye Infectionsmentioning

confidence: 99%

Ocular Parasitic Infections – An Overview

Malla¹,

Goyal²

2016

Advances in Common Eye Infections

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Eyes are said to be the windows of body, by which this beautiful world is visualized. Human eye has a unique structure and is vulnerable to numerous infections. Whenever anatomical structures are breached, host defenses come into play, but if infection is severe and not treated timely, it could lead to visual impairment or blindness. Parasitic infections are considered, the significant causes of ophthalmic diseases worldwide. In this chapter, an overview of ocular parasitic infections (OPI) is detailed out, with an initial brief introduction followed by description of anatomy of the human eye and various defense mechanisms to provide better understanding of the parasitic infections affecting different parts of human eye. The last part includes individual details of various human ocular parasitic infections. Ocular infections can be classified based on either the etiological agent or according to the anatomical site of infection. The parasitic etiological agents include mainly protozoa, helminths and ectoparasites. Due to the complex life cycles of parasites and their tendency to cause wide range of pathologic lesions, different parasites/parasitic infections have been addressed separately, including brief epidemiology, clinical features, diagnosis and treatment.

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Early Aqueous Humor Analysis in Patients with Human Ocular Toxoplasmosis

Cited by 59 publications

References 55 publications

Determinants of immunodiagnostic success in human ocular toxoplasmosis

Determinants of immunodiagnostic success in human ocular toxoplasmosis

Rapid Detection and Identification of Uveitis Pathogens by Qualitative Multiplex Real-Time PCR

Ocular Parasitic Infections – An Overview

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