Clinical and Biological Factors Associated With Recurrences of Severe Toxoplasmic Retinochoroiditis Confirmed by Aqueous Humor Analysis

PURPOSE

To investigate clinical and biological factors influencing recurrences of severe toxoplasmic retinochoroiditis (TRC) confirmed by aqueous humor analysis.

DESIGN

Retrospective case series.

METHODS

Retrospective analysis of 87 subjects with severe TRC, proven by positive Goldmann-Witmer coefficient (GWC), Toxoplasma gondii (T. gondii) immunoblot, or T. gondii-specific polymerase chain reaction (PCR) in aqueous humor. Cases with immunosuppression or retinal scars without previous recorded episode were excluded. Time-dependent, clinical, treatment-related, and biological factors were explored by univariate and multivariate shared frailty survival analyses.

RESULTS

Among 44 included subjects (age, 40.4 ± 17.6 years; follow-up, 8.3 ± 2.7 years), 22 presented recurrences. There was 0.11 recurrence/patient/year and mean disease-free interval was 5.0 ± 2.9 years. The risk of recurrence was higher immediately after an episode (P < .0001). Among recurrent cases, the risk of multiple recurrences was higher when the first recurrence occurred after longer disease-free intervals (P = .046). In univariate analysis, the recurrence risk declined with higher number of intense bands on aqueous T. gondii immunoblot (P = .006), and increased when venous vasculitis was present initially (P = .019). Multivariate analysis confirmed that eyes with more intense bands on immunoblot had fewer recurrences (P = .041). There was a near-significant risk elevation after pyrimethamine/azithromycin treatment (P = .078 and P = .054, univariate and multivariate). Intravenous corticosteroid administration, oral corticosteroid administration, aqueous GWC, and T. gondii PCR did not influence recurrences (P = .12, P = .10, P = .39, and P = .96, respectively).

CONCLUSIONS

Recurrences of severe TRC are not random and may be influenced by clinical and biological factors possibly related to blood-retinal barrier alterations. These results may contribute to identifying biomarkers for TRC reactivation.

Ultrasound Biomicroscopy Findings in Peripheral Vitreoretinal Toxocariasis

Purpose

To describe the morphologic alterations in ultrasound biomicroscopy (UBM) present in peripheral vitreoretinal toxocariasis.

METHODS

An observational prospective study of case series. Fifteen eyes of 15 patients with clinical and laboratory diagnosis of peripheral vitreoretinal toxocariasis were enrolled. The patients were submitted to UBM examination of the region corresponding to the pars plana of the affected eye.

Results

The most common morphologic alterations found by UBM in patients with peripheral vitreoretinal toxocariasis were as follows: vitreal membranes (13 cases), toxocara granuloma (11 cases), and pseudocysts (8 cases). Other less frequent findings were thickening of the ciliary body (6 cases), cystic formation (2 cases), peripheral retinal detachment (2 cases), rectification of the iris root (1 case), and posterior synechiae (1 case).

CONCLUSIONS

UBM allows detection of well-defined morphologic alterations associated with peripheral vitreoretinal toxocariasis, being useful to reinforce the clinical diagnosis

Priming of host resistance to protect cultured rainbow trout Oncorhynchus mykiss against eye flukes and parasite-induced cataracts

In the present study, immunologically naive rainbow trout Oncorhynchus mykiss were experimentally exposed to a low-level Diplostomum spathaceum (Trematoda) infection to stimulate acquired resistance and, along with unexposed controls, were subsequently exposed to natural infection for 8 weeks. The priming of the host resistance, designed to simulate a procedure applicable in aquaculture, decreased the number of establishing parasites compared to untreated controls by the end of the experiment. This effect was slow and did not protect the fish against the parasite-induced cataracts. The results suggest that this type of priming of host resistance is probably inefficient in preventing the deleterious effects of D. spathaceum infection in aquaculture conditions.

What is the importance of Demodex folliculorum in Behçet's disease?

Demodex folliculorum is an obligate parasite and commonly detected in patients with immune system deprivation. This study is planned to document the Demodex folliculorum prevalence among patients with Behçet's disease (BD). The patients who referred to the ophthalmology clinic were included in the study. Fourty patients with BD and 131 patients with refractive errors without any ocular and systemic disease were included. For parasite detection, 3 eyelashes from each inferior eyelid were epilated. Standardized skin surface biopsy (SSSB) was performed for detection of parasite at cheeks of patients. Samples were prepared with Hoyer's solution and investigated under the light microscope. There were 15 female and 25 male in BD group and 61 female and 70 male patients ine control group. Mean ages were 37.62 and 38.38 for BD and control groups, respectively. Demodex folliculorum prevalence at eyelashes was 65% for BD and 10% for control group. SSSB of cheek revealed 7.5% positivity for BD and 10% for control group patients. Statistical analysis documented a significant difference for eyelashes (p < 0.05) which could not be detected for skin results. Investigation of Demodex folliculorum in BD may be useful, even in patients without any complaint, for the treatment of ocular and eyelid discomforts of these patients.

Isolated optic neuritis from an identified Gnathostoma spinigerum

PURPOSE

To describe a patient with isolated monocular optic neuritis caused by an identified Gnathostoma spinigerum infestation.

CASE REPORT

A 21-year-old man developed a swollen eyelid and painful monocular visual loss of his left eye which did not improve after treatment by intravenous steroid and albendazole. A remarkable eosinophilia in his peripheral blood count was demonstrated. The patient subsequently found a live parasite emerged from his lower eyelid and it was successfully removed by himself. Gross and histopathology examinations of the obtained parasite was undertaken. The parasite was identified as Gnathostoma spinigerum. His blood test for Gnathostoma antibody was positive.

DISCUSSION

The etiology of isolated optic neuritis in this patient was Gnathostoma spinigerum which was confirmed by the histopathology of the obtained parasite and the positive serologic test.

CONCLUSIONS

We could identify the exact parasite that was proven to cause an isolated optic neuritis. The immediate removal of a causative parasite maynot result in an improvement of the injured tissue but is beneficial in preventing further destruction as well as future complications.

Following the migration of a Toxocara larva in the retina by optical coherence tomography and fluorescein angiography

BACKGROUND

The Toxocara larva is known to migrate across the retina, but the layer in which it migrates and its effect on the retina has been unknown.

CASE

An ocular Toxocara infection was diagnosed by an immunological test on a vitreous sample from a patient with a retinal lesion that had migrated. Optical coherence tomography (OCT) and fluorescein angiography (FA) were used in this investigation.

OBSERVATIONS

Many small lesions were first detected in the peripheral retina, and vitrectomy was performed because of vitreous haze. Two peripapillary lesions were found during the vitrectomy. OCT of one lesion demonstrated a highly reflective mass located in the nerve fiber layer, and FA showed dye leakage from the lesion as well as hyperfluorescence of the disc. Three weeks later, another lesion was found in the macular area, and OCT and FA findings were the same as for the first lesions. Fluorescein leakage was also observed along the presumed path of the migrating larva.

CONCLUSIONS

The movement of the lesion from the peripapillary area to the macular area suggested that a Toxocara larva had migrated across the retina. OCT images indicated that the larva moved in the nerve fiber layer, and FA showed that it caused severe inflammation along its pathway.

Fuchs heterochromic cyclitis and ocular toxocariasis

PURPOSE

To report the association of Fuchs heterochromic cyclitis (FHC) and ocular toxocariasis in a young adult.

DESIGN

Observational case report.

METHODS

A 26-year-old patient was referred for the management of a unilateral intermediate uveitis associated with a lower peripheral subretinal fibrotic lesion near the pars plana. Diagnosis of FHC was clinically confirmed. Laboratory examination was performed to exclude an infectious condition.

RESULTS

LISA assay detected significant levels of IgG directed against Toxocara canis. Toxoplasmic serology was negative, excluding this differential diagnosis. Other examinations, including complete blood cell count, urinalysis, serum angiotensin-converting enzyme, lysosyme, chest CT scan, and syphilis serology were noncontributive.

CONCLUSIONS

Previous studies have reported on the association of FHC and other parasitic conditions, such as toxoplasmosis but also on herpetic ocular infections. Serologic analysis for toxocariasis may be proposed in patients with FHC and retinal scars in the absence of toxoplasmosis.

Parasite resistance and avoidance behaviour in preventing eye fluke infections in fish

This paper examines the efficiency of acquired resistance in protecting the fish host, rainbow trout (Oncorhynchus mykiss), against the trematode parasite Diplostomum spathaceum, and the hypothesis that fish recognize areas where infective stages are aggregated and show avoidance behaviour. We found that when fish with a low level of infection were held in restricted cages in natural conditions they became infected and developed cataracts as a result of this infection. This suggests that acquired resistance is insufficient in protecting fish against the parasite or the deleterious effects of infection in conditions where fish could not avoid the parasite. Behavioural experiments in the laboratory showed that fish reacted to the parasite cercariae by avoiding the infection source, which decreased the rate of parasite establishment. We conclude that by using a combination of behavioural avoidance and physiological resistance, fish could defend against the parasite more effectively.

[Visual system involvement in selected zoonotic diseases. I. Ocular toxocariasis]

The paper is presenting the selected problems regarding clinical pathology of ophthalmic toxocariasis, as well as methods of its diagnosis, especially immunodiagnosis. The outline of contemporary treatment of this entity is also presented. The data involves the description of Toxocara's life development cycle and data regarding epidemiology of this zoonosis as well.

Toxocara canis: egg presence in Melbourne parks and disease incidence in Victoria

PURPOSE

Toxocara canis can cause blinding eye disease. This study assessed the presence of T. canis eggs in soil from parks in Melbourne and also the incidence of presumed ocular toxocariasis in Victoria.

METHODS

One hundred and eighty soil samples were collected from nine suburban locations in Melbourne, Australia. These were analyzed for the presence of T. canis eggs. A search of laboratory records of T. canis serology requests from Victorian patients over an 8-year period was performed.

RESULTS

Only one soil sample was positive for T. canis eggs. Positive T. canis serology was reported in 13 samples from patients. These patients all had ocular features suggestive of T. canis infection.

CONCLUSION

Toxocara canis eggs are rare in public parks in Melbourne and symptomatic ocular toxocariasis is uncommon in the Victorian population. The acquisition of the disease is unlikely to be from public parks.

[Particularities in the immune response in ocular cysticercosis]

In addition to the unique physiological and immunological features of the eye, previously presented, some parasitic factors of recent knowledge are induced during ocular cysticercosis. A modulation of the immune response of the host, mediated by larval products (a soluble RNA-peptide, some metacestode surface sphingoglycolipids) seems to occur in vivo. These recent findings lead us to make a critical review of the antigenic profiles obtained by Enzyme-linked immunoelectrotransfer blot assay (EITB) on samples collected from malagasy patients.

Ocular toxocariasis in a North Indian population

Sera form 68 patients aged 1-30 years, suffering from posterior pole granuloma, peripheral granuloma, uveitis, endophthalmitis, optic neuritis and with a clinical diagnosis of suspected ocular toxocariasis, were tested for the presence of anti-Toxocara antibodies. Antibodies to Toxocara were detected in 11 (17 per cent) subjects less than 15 years old and three (4 per cent) subjects more than 15 years of age using enzyme-linked immunosorbent assay. None of the controls sera (other helminthic diseases) were positive for anti-Toxocara antibody.

[Selected parameters of cellular immunity in uveitis in children]

Evaluation of lymphocyte in children with uveitis basing on the study of T lymphocyte subpopulation in the peripheral blood using the flow cytometry method is presented. Cytometric analysis of peripheral blood lymphocytes using fluorochrome-marked monoclonal antibodies was carried out in 29 children, aged 6-18, with parasitic uveitis (group A) and with uveitis of another aetiology (group B). Control group consisted of 28 healthy children aged 6-15. The absolute values of T lymphocytes were higher in groups A (x = 1.60 +/- 0.53) and B (x = 1.81 +/- 0.40) compared to controls (x = 1.50 +/- 0.38). The lowest percentage of CD4+ lymphocytes (x = 34.25 +/- 6.06) and the highest percentage of CD8+ lymphocytes (x = 31.14 +/- 6.50) were revealed in children with parasitic uveitis. The lowest index CD4+/CD8+ (x = 1.29 +/- 0.53) in the group of children with parasitic uveitis reflects severe disorders in response regulation. However, the percentage values of NK cells were lower in the two groups of patients compared to controls. The results allow for the assumption that quantitative changes in the subpopulation of peripheral blood lymphocytes are more pronounced in parasitic uveitis.

Animal models in ocular toxocariasis

Ocular toxocariasis is a clearly defined disease. However, much remains to be learned concerning the migratory route, ocular changes, diagnosis and treatment. Studies in paratenic hosts have contributed to our understanding and will yield more information. Various experimental animals have been used, such as mice, rabbits, guinea pigs, primates, hamsters and gerbils. Of these, the last appear to be the most appropriate model due to their high susceptibility to ocular infection. Results obtained from different animal models are often not comparable due to the fact that dose and routes of inoculation are diverse. Early stages in the pathogenesis of ocular toxocariasis are manifested by haemorrhages in the anterior chamber and iris, replaced in time by accumulations of white cells. Ocular migration produces an early cell reaction, formed by an infiltration of neutrophils accompanied by vasculitis and retinal microinfarcts. Over a period of time, an increase of macrophages and the distribution of the infiltrates is observed. Later, granulomatous lesions are formed. These do not necessarily contain a larva and their appearance varies in different animal models. Local production of IgE and the presence of specific IgG have been described.

[Ocular toxocariasis. Value of local immunodiagnosis]

Toxocara canis is a nematode that may be involved in human ocular toxocariasis. Specific immunotesting is of importance but may be negative as toxocara antigens may localize exclusively in vitreous humor. We report here the case of one patient with optic disc toxocariasis granuloma negative for toxocara canis immunodiagnostic on serum. Clinical diagnosis was confirmed by toxocara canis specific enzyme-linked immunosorbent assay (ELISA) on aqueous humor showing elevated titers of antibodies. Systemic steroids associated to specific treatment of toxocariasis were initiated. Follow-up displayed regression of uveitis but development of vitreous bands leading to posterior retinal detachment. Toxocara posterior granuloma is of poor visual prognosis. Moreover, diagnosis may be of late setting, as clinical features are often unrecognized and specific immunodiagnostic on serum negative. Specific immunotesting on aqueous humor is of particular importance to rule out severe clinical differential diagnosis such as retinoblastoma in children. Ultrasound biomicroscopy (UBM) seems to be specific and sensitive in patients with a presumed diagnosis of peripheral toxocariasis. Granuloma surgery appears to yield good clinical results and allows histological confirmation of the diagnosis.

Intraocular antibody production in intraocular inflammation

BACKGROUND

The production of intraocular antibodies is considered a specific marker for active infectious uveitis. The aim of our study was to evaluate the diagnostic value of aqueous humor analysis in consecutive patients referred to a tertiary clinical center.

METHODS

We analyzed 91 paired aqueous humor/serum samples from 89 patients with intraocular inflammation. In 71 patients aqueous humor analysis was used as a positive or negative confirmation of the suspected cause, whereas in 18 patients the clinical diagnosis was completely uncertain. A modified micro-ELISA technique was used to detect intraocular IgG production against Toxoplasma gondii, varicella zoster virus, herpes simplex virus and cytomegalovirus. Statistical analysis was performed using the "Cohen's kappa" test.

RESULTS

Specific intra-ocular antibody production could be detected in 12 (66.7%) of 18 patients with uncertain diagnosis. Subsequently initiated therapy led to clinical improvement in 10 patients, whereas 2 patients remained unchanged. In 2 (2.8%) of 71 patients aqueous humor analysis led to revision of the initially suspected etiology and to a change of therapy. Statistical analysis showed a significant accordance of diagnosis and aqueous humor analysis (P<0.01).

CONCLUSION

In patients with infectious uveitis, analysis of intraocular synthesis of specific antibodies is a valuable tool to establish the etiology rapidly and allows initiation of targeted antimicrobial treatment.

A retrospective study of ocular toxocariasis in Japan: correlation with antibody prevalence and ophthalmological findings of patients with uveitis

To classify the clinical characteristic of ocular toxocariasis in Japan, the prevalence of antibodies to Toxocara antigens was examined in patients with uveitis of unknown aetiology. From 1982 to 1993, serum specimens of 383 cases and intraocular fluid samples of 22 cases were serologically screened for Toxocara infection with five immunodiagnostic tests. Fifty-five sera and 11 intravitreous fluid samples were estimated to have significantly high antibody levels against larval excretory-secretory (ES) antigens of T. canis. Eight cases were positive in both serum and vitreous fluid, and three were positive only in the vitreous fluid. Among the 58 antibody positive samples, 20 cases were omitted due to a lack of detailed description of ocular findings. The remaining 38 cases are described in this study. Of these 38 cases, 34 (89%) were older than 20 years of age. Ocular lesions were located in the posterior fundus in 11 cases, in the peripheral fundus in 18 cases, and in both areas in seven cases. Of the eight cases in which papillary oedema or redness was observed, chorioretinal lesions were also present in seven of them. Tractional retinal detachment was present in five cases. These observations suggest that ocular toxocariasis in Japan has a different clinical profile compared with those in the other countries, and indicate a need for revised classification of ocular toxocariasis.

Aetiological study of the presumed ocular histoplasmosis syndrome in the Netherlands

AIM

To investigate whether presumed ocular histoplasmosis syndrome in the Netherlands is caused by Histoplasma capsulatum and whether other risk factors might play a role in the pathogenesis of this syndrome.

METHODS

23 patients were clinically diagnosed as having presumed ocular histoplasmosis syndrome based on the following criteria: peripapillary atrophy, punched out lesions, a macular disciform lesion or scar in one eye without vitritis. As controls, 66 sex and age matched healthy volunteers were used. Serum samples from both patients and controls were tested for the presence of antibodies against H capsulatum, Toxoplasma gondii, Toxocara canis et cati, Ascaris sp, and for the presence of antigens of Cryptococcus neoformans. Serum samples were also tested for the presence of autoantibodies against retinal or choroidal proteins. To investigate other risk factors, patients and controls were asked to fill in a health and travel related questionnaire. Ten patients with ocular toxoplasmosis were used as a disease control group.

RESULTS

None of the patients with presumed ocular histoplasmosis syndrome or controls had circulating antibodies directed against H capsulatum. No risk factors could be identified and no indications for autoimmunity and no evidence for the role of the other infectious agents could be demonstrated.

CONCLUSIONS

In a Dutch group of patients fulfilling the criteria of a disease currently named presumed ocular histoplasmosis syndrome, no risk factors or relation with the fungus H capsulatum could be detected.

Subconjunctival infection with Dirofilaria repens: serological confirmation of cure following surgery

Cases of zoonotic dirofilariasis infection, caused by Dirofilaria repens, occur widely throughout European, African, Middle Eastern, and Asian countries. The reports of this infection in humans in Spain are limited, and we herein report the case of a 43-year-old man from Elche (Alicante), Spain, who was seen with acute hyperemic reactivity of the temporal limbus of the right eye. A large nematode was visualized on examination and the intact worm was surgically removed. The parasite was identified as a mature but infertile female D repens. The level of serum antibodies against D repens was monitored for 6 months after surgery using immunoenzymatic assays. Serological results confirmed, as expected, the presence of a single worm and the parasitological cure after the surgical removal of the parasite. To our knowledge, this is the fourth autochthonous case of D repens infecting humans in Spain and also the first autochthonous case of subconjunctival localization.

Bilateral ocular toxocariasis demonstrated by aqueous humor enzyme-linked immunosorbent assay

PURPOSE/METHODS

A 14-year-old girl with a history of contact with puppies and chronic bilateral panuveitis was examined. The fundus of the right eye showed an inferotemporal pars plana exudate. The fundus of the left eye showed an elevated posterior mass.

RESULTS/CONCLUSION

Toxocara antibodies in the aqueous humor detected by enzyme-linked immunosorbent assay had a Goldmann-Witmer coefficient of 8.63 in the right eye and 8.94 in the left eye. Toxocariasis may be a cause of bilateral panuveitis.

The spectrum of ocular toxocariasis

Ocular toxocariasis is rare and therefore the spectrum of clinical disease is difficult to establish. We present a review of the clinical features and laboratory findings in a group of patients with positive Toxocara serology and ocular toxocariasis. The clinical spectrum was diverse and milder disease was commoner than might be supposed from reviews of the literature. Eosinophilia was unusual, but featured in two cases of unilateral pars planitis.

Ocular toxocariasis in a patient with repeatedly negative ELISA titre to Toxocara canis

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Pathologic features and immunofluorescent antibody demonstration of ocular microsporidiosis (Encephalitozoon hellem) in seven patients with acquired immunodeficiency syndrome

We studied the clinicopathologic features of seven patients with acquired immunodeficiency syndrome (AIDS) and ocular microsporidiosis. All patients had decreased levels of CD4-positive cells (mean, 26/ml3) and ocular symptoms; five had bilateral punctate epithelial keratopathy, one had intermittent red eyes with conjunctivitis, and one had red eyes only. Light and electron microscopy of corneal and conjunctival biopsy and cytologic specimens and intact globes disclosed microsporidia belonging to the genus Encephalitozoon. Because E. cuniculi and E. hellem, the two species of the Encephalitozoon genus, are morphologically identical, an immunofluorescent antibody technique was used for species identification. In all seven patients, the agent was identified as E. hellem. Pathologic examination of globes obtained after autopsy disclosed E. hellem infection to be restricted to the corneal and conjunctival epithelium. We studied methods for the routine diagnosis of ocular microsporidiosis in patients with AIDS, including the role of immunofluorescent antibody staining.

Ocular toxocariasis in children and youth

The number of infections with larvae of the Toxocara canis worm has been continuously increasing in the Polish population, and the diagnosis and treatment of this disease is difficult. The authors describe 81 cases of eye infection in children and youth at the age of 3 to 18 years. The lesions in 94 eyes were observed for 0.5 to 11 years. In all patients the diagnosis was confirmed by ELISA test. In the clinical picture various forms of uveitis and granuloma of the eye fundus were found. The treatment consisted in general and topical application of antihelmintics, antibiotics and corticosteroids. In 23 eyes photocoagulation, in 11 cryopexy, and in 3 vitrectomy was performed. Clinical improvement was observed in 50 eyes, stabilization of the lesions in 41 eyes, and deterioration in the remaining 3 eyes. The authors conclude that the best results are obtained through conservative treatment combined with photocoagulation and cryopexy.

Toxocara antibodies in patients with visceral or ocular disorder in Slovenia

The incidence of Toxocara antibodies was determined in 319 sera from patients suspected of having Toxocara infection. Serological responses were compared with clinical manifestations and age of the patients. A seropositive reaction was found in 24% of the patients. Highly positive results (OD 0.510-1.000 and OD > 1.000) by ELISA were obtained significantly more frequently in younger patients than in older ones (p < 0.005). The percentage of seropositive patients with visceral disorder was found to decrease with age, whereas the proportion of seropositive patients with ocular disorder increased with age. Serologically confirmed Toxocara infection in Slovenia alerted us to the fact that this health issue should be given due attention in the future.

Biological modifications of the vitreous in intraocular parasitosis: preliminary study

In intraocular parasitosis the immunologic reactions in the vitrectomy-fluids depend on the parasitic agent: there is a lymphocytical reaction without any IgE production in toxoplasmic chorioretinitis, whereas there is a strong hypersensitivity reaction with a local IgE production as well as the presence of eosinophils and an antigenic stimulation in fluids with toxocara parasitosis. The electrophoretic patterns are quite similar in both cases.

Taenia crassiceps: experimental model of intraocular cysticercosis

An experimental model of Taenia crassiceps intraocular cysticercosis was developed in rabbits. The objectives of this study were to analyze the pathophysiology of this parasitic infection and to evaluate the humoral immune response. Cysticerci, inoculated in the anterior chamber of the eye, were able to grow; no inflammatory changes in the eye or anticysticercus antibodies in serum or in aqueous humor were detected during the 12-day period. In contrast, rabbits that had previously been either infected intraperitoneally with living T. crassiceps cysts or immunized intramuscularly with T. crassiceps antigenic extract developed an intense inflammatory reaction in the eye and high levels of antibodies were detected in serum and aqueous humor even before the intraocular inoculation of parasites. Furthermore, intraocular cysticerci showed minimal growth and some were eliminated. These findings support the concept that the eye is an immunologically privileged site in the nonimmunized host and the importance of the immune response in the elimination of this parasitic infection.