Reliability of expert interpretation of retinal photographs for the diagnosis of toxoplasma retinochoroiditis

Automated Machine Learning versus Expert-Designed Models in Ocular Toxoplasmosis: Detection and Lesion Localization Using Fundus Images

PURPOSE

Automated machine learning (AutoML) allows clinicians without coding experience to build their own deep learning (DL) models. This study assesses the performance of AutoML in detecting and localizing ocular toxoplasmosis (OT) lesions in fundus images and compares it to expert-designed models.

METHODS

Ophthalmology trainees without coding experience designed AutoML models using 304 labelled fundus images. We designed a binary model to differentiate OT from normal and an object detection model to visually identify OT lesions.

RESULTS

The AutoML model had an area under the precision-recall curve (AuPRC) of 0.945, sensitivity of 100%, specificity of 83% and accuracy of 93.5% (vs. 94%, 86% and 91% for the bespoke models). The AutoML object detection model had an AuPRC of 0.600 with a precision of 93.3% and recall of 56%. Using a diversified external validation dataset, our model correctly labeled 15 normal fundus images (100%) and 15 OT fundus images (100%), with a mean confidence score of 0.965 and 0.963, respectively.

CONCLUSION

AutoML models created by ophthalmologists without coding experience were comparable or better than expert-designed bespoke models trained on the same dataset. By creatively using AutoML to identify OT lesions on fundus images, our approach brings the whole spectrum of DL model design into the hands of clinicians.

Comparison of immunological and molecular methods for laboratory diagnosis of ocular toxoplasmosis in blood, serum and tears in Brazil

Ocular toxoplasmosis (OT) is caused by protozoan T. gondii. Ophthalmological examination is considered the gold standard for OT diagnosis, and laboratory tests are used for diagnostic confirmation. However, these tests can present different results, which change depending on their basis, on sample type and on patients' clinical alteration. Thus, the aim of the present study is to assess immunodiagnostic and molecular techniques applied in blood, serum and tear fluid to diagnose T. gondii infection in patients seen at an Ophthalmology Clinic. In total, 160 patients were included in the study, 40 of them had OT with active lesions (G1); 40 had OT with healed lesions (G2), 40 had non-toxoplasmic uveitis (G3) and 40 had no ocular alterations (G4). Serum samples were subjected to Immunoenzymatic Assay (ELISA) and to Indirect Immunofluorescence Reaction (IFAT) to search for anti-T. gondii IgM and IgG. Tear fluid samples were analyzed through ELISA for IgA research. All blood and tear fluid samples were subjected to conventional polymerase chain reaction (cPCR) and in a Nested PCR model for T. gondii DNA amplification with targets B1, GRA7 and REP 529. IgG and IgM anti-T. gondii was detected in serum samples from 106 and 15 patients, respectively, when combining ELISA and IFAT results. Anti-T.gondii IgA antibodies were detected in 9.2% of the tear material. Nested PCR with GRA7 target showed higher positivity in blood samples (24.4%); Nested PCR with B1 target showed a higher frequency of positivity in tears (15%). Biological samples of patients with active lesions showed the highest positivity frequencies in all immunodiagnostic assays, as well as in most PCR models. The present results highlighted the need of associating techniques with different fundamentals to confirm OT diagnosis. Furthermore, further tear fluid analyses should be performed to validate this biological material as lesser invasive alternative for the more accurate OT diagnosis.

Ocular Toxoplasmosis

INTRODUCTION

Ocular toxoplasmosis is the leading cause of posterior uveitis worldwide, affecting individuals acrossdifferent age groups. The key to reducing vision loss includes prompt diagnosis and treatment. However, despite the prevalence of ocular toxoplasmosis, there has been little consensus regarding its pathophysiology,clinical features, diagnosis, and especially management.

METHODS

The data sources were literature reviews, including Pub Med and Medline databases. Search terms included toxoplasmosis, retinitis, vasculitis, vitritis, uveitis alone or in combination with, serum, aqueous, vitreous eye, ocular and review.

RESULTS

In this review paper, we have sought to provide an overview of the pathophysiology, epidemiology, and clinical features of the disease, both based on current literature and our own clinical experience. We have also discussed the use of serology, ocular fluid, and ophthalmic investigations that could further facilitate the diagnosis of ocular toxoplasmosis.Different management strategies have been reported worldwide, including newer approaches such as local therapy.

CONCLUSION

A better understanding of critical aspects of ocular toxoplasmosis will hopefully lead to reduced morbidity, including blindness associated with this condition.

Prevalence of Toxoplasmic Retinochoroiditis in an Australian Adult Population: a Community-Based Study

OBJECTIVE

Toxoplasmic retinochoroiditis is the most common clinical manifestation of an infection with the protozoan parasite, Toxoplasma gondii. Up to 50% of the human population is estimated to be infected with T. gondii. However, the epidemiology of toxoplasmic retinochoroiditis is not widely reported. We sought to estimate the prevalence of toxoplasmic retinochoroiditis in Australia using data collected as part of the Busselton Healthy Ageing Study.

DESIGN

Cross-sectional, community-based, prospective cohort study.

PARTICIPANTS

5,020 Australian adults (2,264 men and 2,756 women; age range of 45-69 years and median age of 58 years).

METHODS

Retinal color photographs centered on the optic disc and macula were captured on a digital retinal camera following dilation of the pupils. Three uveitis-subspecialized ophthalmologists assessed each pigmented retinal lesion, and complete concordance of opinion was required to assign a toxoplasmic etiology. Serum T. gondii immunoglobulin (Ig)G levels were measured for those participants with retinal lesions judged to be toxoplasmic retinochoroiditis.

MAIN OUTCOME MEASURES

Prevalence of toxoplasmic retinochoroiditis.

RESULTS

Eight participants (0.16%) had retinal lesions that were considered to have the characteristic appearance of toxoplasmic retinochoroiditis, plus detectable serum T. gondii IgG, consistent with the diagnosis of toxoplasmic retinochoroiditis. On the assumption that 23.81% of retinal lesions occur at the posterior pole, as reported in a community-based survey conducted in Brazil (Sci Rep. 2021;11:3420), the prevalence of toxoplasmic retinochoroiditis was estimated at 0.67% or 1 per 149 persons.

CONCLUSIONS

Toxoplasmic retinochoroiditis is common in Australian adults. Efforts to quantify and address risk factors for human infection with T. gondii are justified.

Utility of blood as the clinical specimen for the diagnosis of ocular toxoplasmosis using uracil DNA glycosylase-supplemented loop-mediated isothermal amplification and real-time polymerase chain reaction assays based on REP-529 sequence and B1 gene

BACKGROUND

Ocular infection with Toxoplasma gondii is a major preventable cause of blindness, especially in young people. The aim of the present study was to assess detection rate of T. gondii DNA in blood samples of clinically diagnosed of ocular toxoplasmosis using uracil DNA glycosylase-supplemented loop-mediated isothermal amplification (UDG-LAMP) and real-time quantitative PCR (qPCR) based on REP-529 and B1.

METHODS

One hundred and seventeen patients with clinically diagnosed ocular toxoplasmosis (OT) were participated in the study as well as 200 control patients. Peripheral blood samples were assessed using UDG-LAMP and qPCR techniques targeting REP-529 and B1.

RESULTS

Detection limits of qPCR using REP-529 and B1 were estimated as 0.1 and 1 fg of T. gondii genomic DNA, respectively. The limits of detection for UDG-LAMP using REP-529 and B1 were 1 and 100 fg, respectively. In this study, 18 and 16 patients were positive in qPCR using REP-529 and B1, respectively. Based on the results of UDG-LAMP, 15 and 14 patients were positive using REP-529 and B1, respectively. Results of the study on patients with active ocular lesion showed that sensitivity of REP-529 and BI targets included 64 and 63%, respectively using qPCR. Sensitivity of 62 and 61%, were concluded from UDG-LAMP using REP-529 and B1 in the blood cases of active ocular lesion. qPCR was more sensitive than UDG-LAMP for the detection of Toxoplasma gondii DNA in peripheral blood samples of patients with clinically diagnosed toxoplasmic chorioretinitis. Furthermore, the REP-529 included a better detection rate for the diagnosis of ocular toxoplasmosis in blood samples, compared to that the B1 gene did. Moreover, the qPCR and UDG-LAMP specificity assessments have demonstrated no amplifications of DNAs extracted from other microorganisms based on REP-529 and B1.

CONCLUSIONS

Data from the current study suggest that qPCR and UDG-LAMP based on the REP-529 are promising diagnostic methods for the diagnosis of ocular toxoplasmosis in blood samples of patients with active chorioretinal lesions.

Spectral optical coherence tomography findings in patients with ocular toxoplasmosis: A case series study

Purpose

Ocular toxoplasmosis is the most common cause of infectious uveitis worldwide. The diagnosis of ocular toxoplasmosis is primarily clinical when it is a typical presentation.With an atypical presentation in the fundus, parasitological diagnosis is a decisive contribution, as well as multimodal imaging. The aim of this study was to investigate vitreal, retinal, and choroidal morphologic changes in active and scarred toxoplasmosis lesions using swept source optical coherence tomography. To our knowledge, it is the first study in Tunisia which describes with precision the retinochoroidal lesions caused by Toxoplasma Gondi by means of the optical coherence tomography (OCT).

Methods

A retrospective analysis of fifteen patients diagnosed with ocular toxoplasmosis was conducted. The patients were examined at ophthalmology service of Farhat Hached Hospital in Sousse Tunisia between January 2002 and December 2019. Complete ophthalmologic examination including best-corrected visual acuity, slit lamp biomicroscopy, dilated biomicroscopic and fundus examinations, colour fundus photography as well as fluorescein angiography and OCT were done at the initial visit and during follow-up.

Result

In the acute phase, thickening, hyper-reflectivity of the neurosensory retina, posterior shading, bumping of the RPE, hyporeflectivity and thickening of choroid were found in 86,6% of patients. During follow-up, neurosensory retinal layers thinning and disorganization, interrupting ofthe ellipsoid zone (EZ), and RPE hyper reflective were noticed in 73% of patients. The choroid became thin and more hyperreflective in 73% of patients. Multiple hyperreflective dots in the vitreous cavity and posterior hyaloid thickening were demonstrated in the acute phase in 60% of patients, with complete resolution and detachment of the posterior hyaloid in the scarred lesions.

Conclusion

The SS-OCT is an important adjunctive imaging modality in the diagnosis and follow-up of patients with ocular toxoplasmosis.

•

Ocular toxoplasmosis is the most common cause of infectious uveitis worldwide.

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The introduction of SD-OCT has enabled imaging with greater resolution, wider sampling area, and improved image registration.

•

The active retinochoroiditis lesion shows thickening with hyper reflectivity of the internal layers of the retina.

•

The retinochoroidal scar shows retinal atrophy, interruption of the IS/OS line, sometimes subretinal fibrosis.

Biological Diagnosis of Ocular Toxoplasmosis: a Nine-Year Retrospective Observational Study

Ocular toxoplasmosis (OT), a parasitic infection of the eye, is considered to be the most important infectious cause of posterior uveitis worldwide. Its prevalence is particularly high in South America, where aggressive Toxoplasma gondii strains are responsible for more-severe presentations. The particular pathophysiology of this infection leads, from recurrence to recurrence, to potentially severe vision impairment. The diagnosis of this infection is usually exclusively based on the clinical examination. However, the symptoms may be misleading and are not always sufficient to confirm a diagnosis of OT. In such cases, biological tests performed by means of several techniques on blood and ocular samples may facilitate the diagnosis. In this study, we analyzed the tests that were performed in our laboratory over a 9-year period every time OT was suspected. Our report highlights that the quality of ocular sampling by ophthalmologists and combinations of several techniques are critical for a reliable biological OT diagnosis.

Ocular toxoplasmosis (OT), i.e., the ocular manifestation of Toxoplasma gondii infection, is one of the leading causes of posterior uveitis. While ocular lesions are often typical, atypical forms often require biological confirmation of the diagnosis. Our study sought to review the biological OT diagnoses made in our laboratory to further assess the role of each test in the diagnostic procedure. All ocular samples sent to our laboratory over the last 9 years for OT diagnosis were included. These samples were analyzed using T. gondii PCR and antibody detection by means of immunoblotting and Candolfi coefficient (CC) determinations, either alone or in combination. Since serum analysis is required to interpret both the CC and immunoblotting, blood serology for T. gondii was also performed in most cases. Of the 249 samples analyzed, 80 (32.1%; 95% confidence interval [95%CI], 26.3 to 37.9) were positive for OT. Of these 80 cases, 52/80 (65.0%; 54.6 to 74.5) displayed a positive PCR, 15/80 (18.8%; 10.2 to 27.3) a positive CC, and 33/80 (41.3%; 95%CI, 30.5 to 52.0) a positive immunoblot result. Overall, 63 of the 80 OT diagnoses (78.8%; 95%CI, 69.8 to 87.7) were made on the basis of a single positive test result. Our study results remind us that current biological diagnostic tools for OT must be employed in combination to obtain an optimal diagnosis based on the precious ocular fluids sampled by ophthalmologists. Clinicobiological studies that are focused on correlating the performances of the different tests with clinical features are critically needed to improve our understanding of the pathophysiology and diagnosis of OT.

IMPORTANCE Ocular toxoplasmosis (OT), a parasitic infection of the eye, is considered to be the most important infectious cause of posterior uveitis worldwide. Its prevalence is particularly high in South America, where aggressive Toxoplasma gondii strains are responsible for more-severe presentations. The particular pathophysiology of this infection leads, from recurrence to recurrence, to potentially severe vision impairment. The diagnosis of this infection is usually exclusively based on the clinical examination. However, the symptoms may be misleading and are not always sufficient to confirm a diagnosis of OT. In such cases, biological tests performed by means of several techniques on blood and ocular samples may facilitate the diagnosis. In this study, we analyzed the tests that were performed in our laboratory over a 9-year period every time OT was suspected. Our report highlights that the quality of ocular sampling by ophthalmologists and combinations of several techniques are critical for a reliable biological OT diagnosis.

When biology supports clinical diagnosis: review of techniques to diagnose ocular toxoplasmosis

Toxoplasmosis is a common infection whose worldwide prevalence is estimated at 30%, with large disparities across the world. Among infected subjects, the prevalence of ocular toxoplasmosis (OT) is, however, limited to about 2% in Europe and 17% in South America. In France, it is estimated that about 1 000 000 patients present either active OT or subsequent chorioretinal scars. Toxoplasmagondii is the first cause of posterior uveitis worldwide, responsible for retinochoroiditis, at times associated with anterior uveitis. To date, there is no consensus yet on how to diagnose OT, which is often based only on clinical presentation. Nevertheless, OT-associated symptoms are often atypical and misleading. Over the last 20 years, tremendous progress has been made in biological tools, enabling parasitologists to confirm the diagnosis in most suspected cases of OT. Using anterior chamber puncture, a safe and fast procedure, ophthalmologists sample aqueous humour for analysis using multiple techniques in order to reach high specificity and sensitivity in OT diagnosis. In this article, we present the different techniques available for the biological diagnosis of OT, along with their characteristics, and propose a diagnostic algorithm designed to select the best of these techniques if clinical examination is not sufficient to ascertain the diagnosis.

Validity and agreement of uveitis experts in interpretation of ocular photographs for diagnosis of Behçet uveitis

Abstract Purpose: To evaluate agreement and estimate sensitivity and specificity of uveitis specialists' interpretation of ocular photographs in diagnosing Behçet uveitis.

METHODS

Fourteen Turkish uveitis specialists, masked to demographic and clinical features of patients, independently labeled ocular photographs (29 Behçet/30 other diagnoses) as "Behçet uveitis" or "non-Behçet." Level of agreement was evaluated using kappa statistics. Photographs were categorized based on ocular signs captured and performance of observers.

RESULTS

Exact agreement with the correct diagnosis was 56-81%. Seven reviewers correctly labeled more than 70% of photographs. Interobserver agreement among those 7 reviewers revealed moderate (κ = 0.41-0.60) or substantial (κ = 0.61-0.80) agreement in 76% of pairs. Smooth layered hypopyon, superficial retinal infiltrate with retinal hemorrhages, and branch retinal vein occlusion with vitreous haze were correctly recognized as Behçet uveitis by majority of reviewers.

CONCLUSIONS

There are ocular signs of Behçet disease that can be considered diagnostic even in the absence of any other clinical information.

Ocular toxoplasmosis: evaluation of lacrimal-specific secretory IgA levels in both patients with active and inactive phases of the disease

Ocular toxoplasmosis can result in recurrent uveitis. Studies have shown that a correlation between active ocular toxoplasmosis and the presence of anti-Toxoplasma gondii secretory IgA (SIgA) in tears. This study compares anti-T. gondii SIgA levels in patients' tears during the acute and inactive phases of toxoplasmic uveitis. Twenty-nine positive tear specific SIgA for T. gondii patients with acute toxoplasmic uveitis were selected and were followed-up for at least two years, when the anti-T. gondii SIgA tears levels were determined. Specific SIgA for T. gondii was negative in 22 patients (75.86%) and positive in seven patients (24.13%) of whom six (85.7%) were followed over three years. Average SIgA levels during the acute phase are 1.54 and decrease significantly to 0.72 (p = 0.0001) during the inactive phase of disease. Because anti-T. gondii SIgA in the tear is negative in 75.86% of patients after the acute phase of infection, T. gondii SIgA levels may be used as a complementary diagnostic marker for active ocular toxoplasmosis.

Active ocular toxoplasmosis in Turkish patients: a report on 109 cases

BACKGROUND

To describe the clinical characteristics of active ocular toxoplasmosis in a large population of Turkish patients.

METHODS

A retrospective study of 109 consecutive patients with active ocular toxoplasmosis seen at the Department of Ophthalmology, Istanbul Faculty of Medicine, from 1995 to 2005.

RESULTS

Fifty-seven patients were female and 52 were male. The mean age at presentation was 25.7 +/- 6.8 years. All patients had positive serum anti-toxoplasma IgG antibodies, but negative IgM antibodies. Preexisting retinochoroidal scars were found in 90 (83%) patients. Central active lesions were significantly more common in eyes without previous involvement than in eyes with preexisting scars (97% vs. 59%). Active lesions were adjacent to a scar in 60 (78.9%) of 76 eyes with preexisting scars. The most common accompanying signs were vitritis (100%), anterior uveitis (49.5%), and periphlebitis (33%). All patients received antiparasitic treatment. Systemic corticosteroids were used in 86% of the patients. Kaplan-Meier survival analysis estimated the cumulative risk of recurrence as 74% at 42 months of follow-up. In 29 (80.5%) of 36 recurrent attacks, active lesions were associated with the scars of the most recent attack. After the resolution of the presenting attack, visual acuity was better than 0.5 in 90%, between 0.1 and 0.5 in 5%, and less than 0.1 in 5% of eyes. Further decrease in visual acuity occurred in only two eyes during our follow-up.

CONCLUSIONS

Most of the patients with active ocular toxoplasmosis have asymptomatic retinochoroidal scars. Proximity of active lesions to the scars, and especially to those of the most recent episode, may have implications for treatment. Although the recurrence risk is high, the visual prognosis is good in most patients with typical ocular toxoplasmosis.

The antibody response in experimental ocular toxoplasmosis

BACKGROUND

The dynamics of the humoral immune response in ocular toxoplasmosis (OT) are poorly understood. We therefore investigated this process in a rabbit model of the disease.

MATERIALS AND METHODS

Of 24 infection-naive adult rabbits, 12 were left untreated and 12 were systematically infected with 5,000 tachyzoites of the non-cystforming BK strain of Toxoplasma gondii. Three months later, all rabbits were inoculated transvitreally with 5,000 tachyzoites of Toxoplasma gondii. Paired samples of aqueous humor and serum were analyzed temporally for their total and specific IgG contents.

RESULTS

In infection-naïve rabbits with primary OT, specific IgG reached detectable levels in the inoculated eyes between 5 and 15 days after inoculation. In infection-immunized rabbits with secondary OT, a significant increase in specific IgG was regularly detected after 5 days. The antibody ratio C was diagnostic (> or =3) from day 15 onward in primary OT and from day 21 onward in secondary OT. In the uninfected partner eyes, the antibody ratio C was found sporadically diagnostic from day 15 onward in primary OT, but at no time in secondary OT. Specific IgG persisted both locally and in the serum until the end of the monitoring period (100 days).

CONCLUSION

Our findings relating to the rabbit model of OT reveal three features of clinical relevance: a diagnostic window precedes the establishment of a humoral immune response; specific antibodies persist long after the cessation of disease activity; and in primary OT, the antibody ratio C may also increase in the uninfected partner eye.

Determinants of immunodiagnostic success in human ocular toxoplasmosis

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.

Imaging techniques for posterior uveitis

PURPOSE OF REVIEW

The goal of this review is to describe the more commonly used imaging techniques and their use to identify causes of vision loss, extent of disease, and distinctive patterns associated with various causes of posterior uveitis.

RECENT FINDINGS

Distinctive patterns seen with new imaging techniques and applications are being described. Ophthalmic CT, fluorescein angiography, indocyanine green angiography, and others are demonstrating inflammation and pathology in posterior uveitis. As our experience grows with these modalities, they are being used increasingly in the diagnosis and management of patients with posterior uveitis.

SUMMARY

This review familiarizes the ophthalmologist with imaging in patients with inflammatory disorders of the retina and choroid. These modalities can help with the diagnosis, treatment, and monitoring of patients with uveitis.

Long-term ocular prognosis in 327 children with congenital toxoplasmosis

OBJECTIVE

Retinochoroiditis is the most frequent consequence of congenital toxoplasmosis. Early diagnosis and treatment are believed to reduce the risk of visual impairment. We report on the clinical evolution of ocular lesions and final visual function in a prospective cohort of congenitally infected children who were identified during monthly maternal prenatal screening.

METHODS

The study included 327 congenitally infected children who were monitored for up to 14 years at the Croix Rousse Hospital in Lyon, France. Data on date of maternal infection; time and type of therapy; antenatal, neonatal, and postnatal work-ups; and ocular status were analyzed.

RESULTS

All mothers but 52 had been treated. Pyrimethamine and sulfadiazine was given in utero to 38% of children and after birth to 72% of newborns. Fansidar was given for an average duration of 337 days in all but 2 children. After a median follow-up of 6 years, 79 (24%) children had at least 1 retinochoroidal lesion. In 23 (29%) of them, at least 1 new event had been diagnosed up to 10 years after detection of the first lesions: reactivation of an existing lesion (1 case), new lesion in a previously healthy location (19 cases), or both (3 cases). Fifty-five children had lesions in 1 eye; of the 45 children for whom final visual acuity data were available, 31 (69%) had normal vision. Twenty-four children had lesions in both eyes; of the 21 for whom final visual acuity data were available, 11 had normal vision in both eyes. None had bilateral visual impairment.

CONCLUSIONS

Clinicians, parents, and elder children with congenital infection should be informed that late-onset retinal lesions and relapse can occur many years after birth but that the overall ocular prognosis of congenital toxoplasmosis is satisfactory when infection is identified early and treated accordingly.

Ocular manifestations of toxoplasmosis

PURPOSE OF REVIEW

The concepts of toxoplasmosis and its ocular manifestations in humans have thoroughly changed in the past 3 years. This review addresses new epidemiologic data, specifically the occurrence of ocular disease in postnatal infections, and puts the changed views on the frequency and pathogenesis of toxoplasmic ocular manifestations into historical perspective.

RECENT FINDINGS

Newly described clinical presentations are discussed together with their recent diagnostic possibilities. The new data on congenital or postnatal acquisition of infection and their importance for ocular involvement are presented as well as the high prevalence of 79% of recurrent disease in ocular toxoplasmosis, which cannot be prevented by short-term treatments. Recently published analyses of literature showed, unexpectedly, the lack of efficacy of short-term treatments for ocular disease as well as of the long-term prenatal treatments on fetal transmission rate and the severity of congenital disease.

SUMMARY

The recent guidelines for treatment are included together with the up-to-date recommendations for the treatment of ocular toxoplasmosis in the immunosuppressed host.

Comparison of enzyme-linked immunosorbent assay, immunoblotting, and PCR for diagnosis of toxoplasmic chorioretinitis

Ocular toxoplasmosis is the major cause of posterior uvetis in European populations. The clinical diagnosis of toxoplasmic chorioretinitis is based upon ophthalmoscopic findings, which are often but not always typical. Laboratory testing is therefore important to confirm the etiology of the disease. In the present 2-year prospective study, the relative diagnostic sensitivities of the three analytical techniques (enzyme-linked immunosorbent assay [ELISA], immunoblotting, and PCR) were compared by using a group of patients (n = 19) with suspected ocular toxoplasmosis. The relative specificities of the three techniques were assessed by including two control groups of patients: one with nontoxoplasmic and noninflammatory ocular disease (n = 48) and the other with nontoxoplasmic and inflammatory ocular disease (n = 20). All 19 of the clinically suspect patients had serological evidence of exposure to Toxoplasma gondii: 17 had been previously infected, and 2 had current infection. The analysis of paired aqueous humor and serum samples by ELISA and immunoblotting revealed the local production of specific antibodies of the immunoglobulin G type in 63% (12 of 19) and 53% (10 of 19) of patients, respectively. PCR analysis of aqueous humor samples confirmed the presence of T. gondii DNA in 28% (5 of 18) of cases. When combined, ELISA, immunoblotting, and PCR findings confirmed the toxoplasmic origin of retinal lesions in 83% (15 of 18) of patients. The relative specificities of the three techniques were 89% for ELISA and immunoblotting and 100% for PCR.