Ocular toxoplasmosis: an update and review of the literature

Toxoplasmosis in animals and humans: a neglected zoonotic disease in Bangladesh

Toxoplasmosis, caused by Toxoplasma gondii, is a zoonotic disease that affects a wide range of warm-blooded animals, including humans. The parasite undergoes both sexual and asexual reproduction in intermediate hosts (humans and animals) and definitive hosts (cats). Transmission in humans occurs through consuming oocyst-contaminated water, fruits, vegetables, and raw or undercooked meats. In Bangladesh, several factors contribute to an increased risk of contracting toxoplasmosis. The parasite is reported to cause diseases among livestock such as goats and sheep in this country, and it has also been associated with some human illnesses. Toxoplasmosis prevalence varies significantly worldwide, with developing countries like Bangladesh experiencing higher rates. Diagnostic methods include both conventional non-DNA-based tests and molecular detection techniques, while treatment options involve using antiparasitic drugs like sulfadiazine and pyrimethamine. To control toxoplasmosis, essential steps include improving sanitation, promoting safe food handling, and educating the public about risks related to cat ownership and undercooked meat consumption. Implementing prenatal screening and treatment is also important. With the growing popularity of pet ownership in urban areas, it becomes essential to emphasize the veterinary and public health significance of toxoplasmosis in Bangladesh. This article comprehensively reviews various aspects of toxoplasmosis, with a specific focus on the situation in Bangladesh.

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.

Azithromycin concentration in rabbits' plasma and posterior segment of the eyes following oral drug administration: a dose-finding study for the application in ocular toxoplasmosis

INTRODUCTION

Azithromycin has been used as an ocular toxoplasmosis alternative treatment due to its pharmacokinetic profiles. However, sufficient concentrations to promote toxoplasmosis eradication is still unknown. This study was aimed to evaluate azithromycin levels in rabbits after three regimens equivalent to human doses for ocular toxoplasmosis.

METHODS

Three groups of New Zealand albino rabbits were given one of the following: azithromycin at 26 mg/kg BW daily (Group 1), 26 mg/kg BW every two days (Group 2), and 50 mg/kg BW once weekly (Group 3) for 14 days. Plasma and ocular azithromycin concentrations were examined.

RESULTS

Following 14 days, median ratio of plasma maximum azithromycin concentration to the minimum inhibitory concentration for Toxoplasma gondii (C-max/MIC) for Group 1, and 2 were 51.29, 5.33, while Group 3 was undetected. The median azithromycin concentration in the retina-choroid was higher than the MIC in Group 1 (1356.0 ng/ml) and Group 2 (189.0 ng/ml), but not in Group 3.

CONCLUSION

Azithromycin administered orally at the dose of 26 mg/kg BW daily or 26 mg/kg BW every two days resulted a sufficient criteria of C-max/MIC as well as retina-choroid concentration needed for its parasiticidal activity. However, well-conducted clinical trial is warranted to support its therapeutic potential in ocular toxoplasmosis.

An illustration of ocular toxoplasmosis with consequent lenticular opacities and asteroid hyalosis

Inactive ocular toxoplasmosis (OT) is not confined to immunocompromised patients but is also common in immunocompetent patients. It could result in a loss of vision, asteroid hyalosis, lenticular opacity and peripheral chorioretinal scar. More often than not, misdiagnosing the lesion may occur because of the lack of presenting symptoms. Therefore, this article aims to highlight OT and its consequences, emphasising the approach that must be followed to diagnose and manage the disease optimally. This case report is about a 24-year-old woman who had blurred vision in her left eye from the age of 9 years. After dilation for fundus examination and taking the patient for retinal imaging, the fundus showed a clearly defined pigmented chorioretinal scar on the temporal side of the macula.Contribution: As the disease has the ability for retinal complications, documenting any progressive developments of the disease is essential to manage the patient better.

Separate To Operate: the Centriole-Free Inner Core of the Centrosome Regulates the Assembly of the Intranuclear Spindle in Toxoplasma gondii

Centrosomes are the main microtubule-organizing center of the cell. They are normally formed by two centrioles, embedded in a cloud of proteins known as pericentriolar material (PCM). The PCM ascribes centrioles with their microtubule nucleation capacity. Toxoplasma gondii, the causative agent of toxoplasmosis, divides by endodyogeny. Successful cell division is critical for pathogenesis. The centrosome, one of the microtubule organizing centers of the cell, plays central roles in orchestrating the temporal and physical coordination of major organelle segregation and daughter cell formation during endodyogeny. The Toxoplasma centrosome is constituted by multiple domains: an outer core, distal from the nucleus; a middle core; and an inner core, proximal to the nucleus. This modular organization has been proposed to underlie T. gondii's cell division plasticity. However, the role of the inner core remains undeciphered. Here, we focus on understanding the function of the inner core by finely studying the localization and role of its only known molecular marker; TgCep250L1. We show that upon conditional degradation of TgCep250L1 parasites are unable to survive. Mutants exhibit severe nuclear segregation defects. In addition, the rest of the centrosome, defined by the position of the centrioles, disconnects from the nucleus. We explore the structural defects underlying these phenotypes by ultrastructure expansion microscopy. We show that TgCep250L1's location changes with respect to other markers, and these changes encompass the formation of the mitotic spindle. Moreover, we show that in the absence of TgCep250L1, the microtubule binding protein TgEB1, fails to localize at the mitotic spindle, while unsegregated nuclei accumulate at the residual body. Overall, our data support a model in which the inner core of the T. gondii centrosome critically participates in cell division by directly impacting the formation or stability of the mitotic spindle. IMPORTANCE Toxoplasma gondii parasites cause toxoplasmosis, arguably the most widespread and prevalent parasitosis of humans and animals. During the clinically relevant stage of its life cycle, the parasites divide by endodyogeny. In this mode of division, the nucleus, containing loosely packed chromatin and a virtually intact nuclear envelope, parcels into two daughter cells generated within a common mother cell cytoplasm. The centrosome is a microtubule-organizing center critical for orchestrating the multiple simultaneously occurring events of endodyogeny. It is organized in two distinct domains: the outer and inner cores. We demonstrate here that the inner core protein TgCEP250L1 is required for replication of T. gondii. Lack of TgCEP250L1 renders parasites able to form daughter cells, while unable to segregate their nuclei. We determine that, in the absence of TgCEP250L1, the mitotic spindle, which is responsible for karyokinesis, does not assemble. Our results support a role for the inner core in nucleation or stabilization of the mitotic spindle in T. gondii.

Seroprevalence of Toxoplasmosis among Shelter-Housed Felines in a Philadelphia Suburb

Simple Summary

Cats serve as a host for a parasite called Toxoplasma gondii. This parasite can infect other animal species, including humans, and, therefore, the study of toxoplasmosis is relevant to both human and animal health. In this study, we analyzed blood samples from 84 shelter-housed cats to determine if they had been exposed to T. gondii. Our results revealed that 28.6% of the cats in our study had been exposed to toxoplasmosis. This study serves as a pilot study for further investigation into the rates of toxoplasmosis infection in shelter-housed felines.

Abstract

Members of the Felidae family are the definitive host of the ubiquitous zoonotic parasite Toxoplasma gondii. Few studies have been conducted to determine the epidemiology of T. gondii in domestic felines within animal shelter populations. The goal of this study was to assess seroprevalence in a limited-admission shelter in the greater Philadelphia area. Serum samples were collected from cats at a shelter in Media, Pennsylvania during the summer of 2018 to assess the proportion of the population that was IgM or IgG seropositive for antibodies against T. gondii, using a commercially available ELISA. Out of the 84 cats that were sampled, 24 cats were seropositive, giving a population prevalence of 28.6%. Nine cats were seropositive for IgM, nine were seropositive for IgG, and six were seropositive for both IgM and IgG. Based on our data, we found that a large percentage of this population was seronegative. Although the sample size in this study was limited and prevented us from obtaining statistically significant results, this research can serve as a pilot study for further investigations into the seroprevalence of toxoplasmosis among shelter-housed felines.

Toxoplasmosis in Human and Animals Around the World. Diagnosis and Perspectives in the One Health Approach

Toxoplasmosis is a unique health disease that significantly affects the health of humans, domestic animals, wildlife and is present in ecosystems, including water, soil and food. Toxoplasma gondii is one of the best-adapted parasites in the word. This parasite is able to persist for long periods in its hosts, in different geographic regions of the word. This review summarizes the current literature of these themes, focusing on: (1) toxoplasmosis, a zoonotic infection; (2) One health approach and toxoplasmosis; (3) human toxoplasmosis; (4) animal toxoplasmosis; (5) toxoplasmosis diagnosis, as immunological, parasitological and molecular diagnosis; (6) T. gondii outbreaks caused by infected meat, milk and dairy products, as well as, vegetables and water consume; (7) studies in experimental models; (8) genetic characterization of T. gondii strains; (9) extracellular vesicles and miRNA; and (10) future perspectives on T. gondii and toxoplasmosis. The vast prevalence of toxoplasmosis in both humans and animals and the dispersion and resistence of T. gondii parasites in environment highlight the importance of the one health approach in diagnostic and control of the disease. Here the different aspects of the one health approach are presented and discussed.

The Role of Corticosteroids in Treating Acute Ocular Toxoplasmosis in an Immunocompetent Patient: A Case Report

Background

This study aimed to report a case who was treated with corticosteroids and anti- parasitic agents for ocular toxoplasmosis, but who progressed to acute retinal necrosis, and finally retinal detachment.

Case Presentation

A 42-year-old man presented to the ophthalmology clinic with a 1-month history of progressive blurred vision and floaters in his right eye. His best visual acuity (VA) was 20/20 in both eyes. The anterior segment was unremarkable. Funduscopic examination of the right eye revealed active lesions of whitish foci of chorioretinitis with surrounding edema along the superonasal vessels, and retinal vasculitis with perivascular sheathing. Serologic testing was positive for Toxoplasma gondii IgM and IgG, but negative for other virus- and syphilis infections. Ocular toxoplasmosis was diagnosed. Corticosteroids and anti-parasitic agents were given simultaneously, but his right eye VA became 20/100. Funduscopic examination revealed retinal necrosis with localized retinal breaks. We immediately performed focal photocoagulation, however, his right eye progressed to retinal detachment and required vitrectomy.

Conclusion

Early administration of systemic corticosteroids in patients with acquired acute ocular toxoplasmosis may lead to complications that impair vision. Intensive observation should be arranged after corticosteroid use.

Toxoplasma gondii in humans and animals in Japan: An epidemiological overview

Toxoplasmosis is a cosmopolitan protozoan zoonosis caused by Toxoplasma gondii infamous for inducing severe clinical manifestations in humans. Although the disease affects at least one billion people worldwide, it is neglected in many countries including developed ones. In literature, the epidemiological data documenting the actual incidence of the disease in humans and domestic animals from Japan are limited and importantly many earlier papers on T. gondii infections were published in Japanese and a considerable part is not available online. Herein, we review the current summary about the epidemiological situation of T. gondii infection in Japan and the potential associated risk factors in humans and animals as well as the different T. gondii genotypes isolated in Japan. Several T. gondii isolates have been identified among cats (TgCatJpTy1/k-3, TgCatJpGi1/TaJ, TgCatJpObi1 and TgCatJpOk1-4) and goats (TgGoatJpOk1-13). This literature review underscores the need for a nationwide investigation of T. gondii infection in Japanese people and assessment of the socioeconomic impact of the disease burden. Furthermore, epidemiological studies in domestic and wild animals and estimation of degree of contamination of soil or water with T. gondii oocysts are needed, for a better understanding of the scope of this public health concern.

Comparison of real-time PCR and nested PCR for toxoplasmosis diagnosis in toxoplasmic retinochoroiditis patients

Backgrounds

PCR is a proper technique that significantly improves toxoplasmosis diagnosis. However, a more sensitive technique is required. This study compared real-time PCR with nested PCR using B1, SAG-4, and MAG-1 bradyzoite genes to diagnose toxoplasmosis in toxoplasmic retinochoroiditis patients.

Methods

Blood samples were collected from 10 patients with active toxoplasmic chorioretinal lesions and 10 healthy individuals. Blood samples including peripheral blood mononuclear cells (PBMCs), serum and whole blood samples were used for DNA extraction. Serum was also used to detect anti-toxoplasma IgG and IgM antibodies. Nested PCR and real-time PCR were performed using B1, SAG-4, and MAG-1 target genes.

Results

Five (50%) out of the 10 patients were tested positive for toxoplasmosis with nested PCR using the PBMC samples. All the five patients tested positive with nested PCR were also tested positive for toxoplasmosis with real-time PCR using the PBMC samples. The real-time PCR results demonstrated that 9(90%) out of the 10 patients were positive based on B1 and the remaining one (10%) was positive only based on MAG-1. In general, of the patients, five (50%) were positive using SAG-4 and three (30%) were positive in term of MAG-1 using PBMCs with real-time PCR.

Conclusion

It appears that PBMC samples have the best performance as the PCR extraction method and are a good source for toxoplasmosis diagnosis. The use of B22 and B23 target genes due to their high sensitivity and specificity along with bradyzoite genes are recommended for toxoplasmosis diagnosis using PBMC samples with real-time PCR.

[Asymmetric form of pigmentary retinopathy (case study)]

Unilateral pigmentary retinopathy (PR) is a rare, atypical form of hereditary retinal pathology. Different types of secondary retinopathy associated with various non-hereditary diseases, trauma or intoxication can imitate unilateral PR. Therefore, it is important to determine the cause of visual disorders and differentiate between unilateral and asymmetric PR. The article presents an example of using modern structural and functional diagnostic methods that helped diagnose the asymmetric form of the disease in a patient with suspected unilateral PR.

Infections and glaucoma

Glaucoma is an intraocular pressure-related ophthalmic disease with multiple causes that results in an optic neuropathy and vision loss. Intraocular pressure elevation is among its strongest risk factors. While glaucoma is mostly primary in etiology, secondary glaucoma is not infrequent. Recognizing its cause is imperative, since treatment is often different depending on the pathophysiologic mechanism. Numerous clinically relevant ophthalmic infections can result in robust inflammatory responses that may result in pressure elevation or intraocular anatomic configurations that predispose to pressure elevation. Knowing the mechanisms by which these infections can lead to glaucoma is critical in treating, and we consolidate what is currently known in regards to how infectious diseases lead to glaucoma.

Atypical Bilateral Multifocal Congenital Toxoplasmosis Retinochoroiditis: Case Report With Literature Review

Background

Toxoplasmosis gondii is ubiquitously present on earth and infection, including congenital infection, is common. Neurological, developmental, and ocular effects can be devastating in the congenital toxoplasmosis population. At present, there is no standard, nation-wide neonatal screening for this disease in the United States.

Case Presentation

A 17-month-old Caucasian female presented to our institution by way of referral for macular scarring. She was diagnosed with intrauterine growth retardation and born with low birth weight and microcephaly at an outside institution, but no systemic workup was conducted at that time. On ocular examination, she was found to have nystagmus and extensive multifocal chorioretinal pigmented scars involving the macula and peripheral retina in both eyes with fibrous vitreous strands extending between scars in the right eye. Toxoplasmosis immunoglobulin G was found to be highly positive. Magnetic resonance imaging of the brain showed supratentorial intracranial calcifications.

Conclusions

Our patient presented with severe chorioretinal lesions, microcephaly, and nystagmus with a positive immunoglobulin G toxoplasmosis titer. She did not receive any evaluation, including TORCH infectious panel workup, on being born with low birth weight and microcephaly. There are currently no national programs in place for toxoplasmosis to be included in routine neonatal screening, despite the grave sequelae of congenital infection or that studies in other countries have shown cost-effectiveness in early screening and treatment.

[Intravitreal clindamycin injection in toxoplasma retinochoroiditis: About 9 cases in the ophthalmology department of the CHU de Bordeaux]

INTRODUCTION

Toxoplasma retinochoroiditis (TRC) is the main cause of posterior uveitis in immunocompetent patients. Several studies have shown safety and efficacy of treatment with intravitreal clindamycin injection in patients with contraindications, inadequate response or side effects with classic oral therapy. The goal of this study is to describe anatomic and functional results of local treatment with intravitreal clindamycin injection.

MATERIALS AND METHODS

We performed an observational, retrospective, single-center study in the ophthalmology service of Bordeaux university medical center between December 2017 and January 2020 on management of toxoplasma retinochoroiditis by intravitreal clindamycin injection. We analyzed the efficacy of this treatment on improvement in visual acuity, decrease in size of the retinal lesion and decrease in macular thickness.

RESULTS

A total of 10 eyes of 9 patients were injected. Only a single injection was required in 9 of the 10 cases. Injections demonstrated improvement in the 3 study criteria; visual acuity went from a mean of 1 LogMAR (1.07±0.77) pre-injection to 0.4 LogMAR (0.43±0.53) at 6 months, lesion size decreased by 51%, and macular thickness decreased by 78μm over the follow-up period.

CONCLUSION

Intravitreal clindamycin injections are safe and effective for the treatment of TRC. They offer an alternative in patients with allergies, side effects or inadequate response to classic oral therapy.

Ocular toxoplasmosis: phenotype differences between toxoplasma IgM positive and IgM negative patients in a large cohort

PURPOSE

To investigate the differences in demographics and clinical characteristics of patients diagnosed with ocular toxoplasmosis according to their IgM status.

METHODS

Retrospective case note analysis was carried out on patients who tested positive for serum Toxoplasma gondii-specific IgM antibodies (IgM+) as well as a comparator group who tested negative for serum IgM (IgM-), but positive for serum IgG. Patient demographics and clinical features were compared between the two groups to evaluate for any significant differences.

RESULTS

One hundred and six patients were included in the study between March 2011 and June 2018, consisting of 37 in the IgM +group and 69 in the IgM- group. Patients in the IgM +group were significantly older (51.1 vs 34.1 years, p<0.0001), more likely to present with central macular lesions (32% vs 12%, p=0.012), and more likely to develop rhegmatogenous retinal detachment (11% vs 1%, p=0.049). In contrast, patients in the IgM- group were more likely present with pain (20% vs 3%, 0.017) and exhibit more severe inflammation of the anterior chamber and vitreous (p<0.05). Overall, retinal lesions were more likely to be superotemporal (55%) and superonasal (31%). Furthermore, age was associated with larger (p=0.003) and more peripheral lesions (p=0.007).

CONCLUSIONS

This study demonstrated significant differences in clinical characteristics of ocular toxoplasmosis according to serum IgM status. IgM+ patients were older, less likely to report pain, had lower levels of intraocular inflammation, but were more likely to have macular involvement. We also found age to be correlated with larger and more peripheral lesions.

Acquisition of Host Cytosolic Protein by Toxoplasma gondii Bradyzoites

Toxoplasma gondii is a protozoan parasite that persists in the central nervous system as intracellular chronic-stage bradyzoites that are encapsulated by a thick cyst wall. While the cyst wall separates bradyzoites from the host cytosol, it has been posited that small solutes can traverse the cyst wall to sustain bradyzoites. Recently, it was found that host cytosolic macromolecules can cross the parasitophorous vacuole and are ingested and digested by actively replicating acute-stage tachyzoites. However, the extent to which bradyzoites have an active ingestion pathway remained unknown. To interrogate this, we modified previously published protocols that look at tachyzoite acquisition and digestion of host proteins by measuring parasite accumulation of a host-expressed reporter protein after impairment of an endolysosomal protease (cathepsin protease L [CPL]). Using two cystogenic parasite strains (ME49 and Pru), we demonstrate that T. gondii bradyzoites can ingest host-derived cytosolic mCherry. Bradyzoites acquire host mCherry within 4 h of invasion and after cyst wall formation. This study provides direct evidence that host macromolecules can be internalized by T. gondii bradyzoites across the cyst wall in infected cells.IMPORTANCE Chronic infection of humans with Toxoplasma gondii is common, but little is known about how this intracellular parasite obtains the resources that it needs to persist indefinitely inside neurons and muscle cells. Here, we provide evidence that the chronic-stage form of T. gondii can internalize proteins from the cytosol of infected cells despite residing within an intracellular cyst that is surrounded by a cyst wall. We also show that accumulation of host-derived protein within the chronic-stage parasites is enhanced by disruption of a parasite protease, suggesting that such protein is normally degraded to generate peptides and amino acids. Taken together, our findings imply that chronic-stage T. gondii can ingest and digest host proteins, potentially to support its persistence.

Pathophysiology of ocular toxoplasmosis: Facts and open questions

Infections with the protozoan parasite Toxoplasma gondii are frequent, but one of its main consequences, ocular toxoplasmosis (OT), remains poorly understood. While its clinical description has recently attracted more attention and publications, the underlying pathophysiological mechanisms are only sparsely elucidated, which is partly due to the inherent difficulties to establish relevant animal models. Furthermore, the particularities of the ocular environment explain why the abundant knowledge on systemic toxoplasmosis cannot be just transferred to the ocular situation. However, studies undertaken in mouse models have revealed a central role of interferon gamma (IFNγ) and, more surprisingly, interleukin 17 (IL17), in ocular pathology and parasite control. These studies also show the importance of the genetic background of the infective Toxoplasma strain. Indeed, infections due to exotic strains show a completely different pathophysiology, which translates in a different clinical outcome. These elements should lead to more individualized therapy. Furthermore, the recent advance in understanding the immune response during OT paved the way to new research leads, involving immune pathways poorly studied in this particular setting, such as type I and type III interferons. In any case, deeper knowledge of the mechanisms of this pathology is needed to establish new, more targeted treatment schemes.

The Structural and Molecular Underpinnings of Gametogenesis in Toxoplasma gondii

Toxoplasma gondii is a widely prevalent protozoan parasite member of the phylum Apicomplexa. It causes disease in humans with clinical outcomes ranging from an asymptomatic manifestation to eye disease to reproductive failure and neurological symptoms. In farm animals, and particularly in sheep, toxoplasmosis costs the industry millions by profoundly affecting their reproductive potential. As do all the parasites in the phylum, T. gondii parasites go through sexual and asexual replication in the context of an heteroxenic life cycle involving members of the Felidae family and any warm-blooded vertebrate as definitive and intermediate hosts, respectively. During sexual replication, merozoites differentiate into female and male gametes; their combination gives rise to a zygotes which evolve into sporozoites that encyst and are shed in cat's feces as environmentally resistant oocysts. During zygote formation T. gondii parasites are diploid providing the parasite with a window of opportunity for genetic admixture making this a key step in the generation of genetic diversity. In addition, oocyst formation and shedding are central to dissemination and environmental contamination with infectious parasite forms. In this minireview we summarize the current state of the art on the process of gametogenesis. We discuss the unique structures of macro and microgametes, an insight acquired through classical techniques, as well as the more recently attained molecular understanding of the routes leading up to these life forms by in vitro and in vivo systems. We pose a number of unanswered questions and discuss these in the context of the latest findings on molecular cues mediating stage switching, and the implication for the field of newly available in vitro tools.

Granulomas in parasitic diseases: the good and the bad

Parasitic diseases affect more than one billion people worldwide, and most of them are chronic conditions in which the treatment and prevention are difficult. The appearance of granulomas, defined as organized and compact structures of macrophages and other immune cells, during various parasitic diseases is frequent, since these structures will only form when individual immune cells do not control the invading agent. Th2-typering various parasitic diseases are frequent, since these structures will only form when individual immune cells do not control the invading agent. The characterization of granulomas in different parasitic diseases, as well as recent findings in this field, is discussed in this review, in order to understand the significance of the granuloma and its modulation in the host-parasite interaction and in the immune, pathological, and parasitological aspects of this interaction. The parasitic granulomatous diseases granulomatous amebic encephalitis, toxoplasmosis, leishmaniasis, neurocysticercosis, and schistosomiasis mansoni are discussed as well as the mechanistic and dynamical aspects of the infectious granulomas.

Toxoplasma gondii SAG2 type III in an atypical presentation of ocular toxoplasmosis in Indonesia

OBJECTIVE

This study aimed to perform genotyping of Toxoplasma gondii strain or variant causing atypical toxoplasmic uveitis in Indonesian patients.

METHODS

Ocular fluid samples originating from 46 uveitis patients with non-specific ocular manifestations were analysed for Toxoplasma infection by PCR of the B1 locus. The clonal type was determined by amplification, sequencing and phylogenetic analysis of SAG2 and GRA6 loci in B1-positive samples. Clinical data were obtained from the medical records.

RESULTS

Pan uveitis was the most frequent manifestation (65.2%) and mostly unilateral (76.1%). PCR of the B1 locus identified eight positive subjects (12.5%); six had panuveitis and two of these had diabetes mellitus. Phylogenetic analysis with maximum likelihood of the SAG2 locus in the B1-positive samples resulted in Toxoplasma gondii SAG2 type III allele. No positive result was obtained from the PCR of GRA6 locus.

CONCLUSION

Toxoplasma gondii SAG2-type III allele was identified in an atypical presentation of toxoplasmic uveitis in Indonesia.

Long-term Results of Trimethoprim-Sulfamethoxazole Versus Placebo to Reduce the Risk of Recurrent Toxoplasma gondii Retinochoroiditis

PURPOSE

To compare the effects of 1 year of treatment with trimethoprim-sulfamethoxazole (TMP-SMZ) vs placebo in reducing the risk of recurrence of toxoplasmic retinochoroiditis during a 6-year follow-up period.

DESIGN

Randomized, double-masked clinical trial.

METHODS

This cohort included 141 subjects recruited in Campinas, Brazil. The inclusion criterion was unilateral active recurrent toxoplasmic retinochoroiditis. All subjects were treated with 1 dose of TMP-SMZ (160 mg/800 mg) twice daily for 45 days, and all lesions healed after this treatment. After this initial treatment, subjects were randomly assigned to group 1 (1 TMP-SMZ dose every other day for 311 days) or group 2 (1 identical placebo tablet containing starch with no active ingredients every other day for 311 days). Between the second and sixth years of follow-up appointments, none of the subjects received treatment unless a new recurrence episode had occurred. The primary outcomes were recurrent toxoplasmic retinochoroiditis within the first year of follow-up and recurrent toxoplasmic retinochoroiditis in the 6 years of follow-up.

RESULTS

The cumulative probability of recurrence 1, 2, 3, 4, 5, and 6 years after the initial infection was, respectively, 13.0% (9/69), 17.4% (12/69), 20.3% (14/69), 23.2% (16/69), 26.1% (18/69), and 27.5% (19/69) in the placebo group and 0%, 0%, 0%, 0%, 0%, and 1.4% (1/72) in the TMP-SMZ group (P < .001; log-rank test). There were 3 cases (3/69; 4.3%) of multiple recurrences in the same individual in the placebo group. No treatment-limiting toxicity or side effects were observed in either group. New recurrences were more frequent among female subjects.

CONCLUSIONS

TMP-SMZ may be used safely for prophylaxis of recurrent toxoplasmic retinochoroiditis and may provide long-term benefits.

VEGF Production Is Regulated by the AKT/ERK1/2 Signaling Pathway and Controls the Proliferation of Toxoplasma gondii in ARPE-19 Cells

The retina is the primary site of Toxoplasma gondii infection in the eye, and choroidal neovascularization in ocular toxoplasmosis is one of the most important causes of visual impairment. Vascular endothelial growth factor (VEGF) is one of the key regulators of blood vessel development, however, little is known about the mechanisms of T. gondii-induced VEGF production in ocular toxoplasmosis. Here, we investigate the effect of T. gondii on VEGF production regulation in human retinal pigment epithelium ARPE-19 cells and attempted to unveil the underlying mechanism of this event by focusing on the interaction between parasite and the selected host intracellular signaling pathways. T. gondii infection increased the expression of VEGF mRNA and protein in ARPE-19 cells in parasite burden- and infection time-dependent manner. The proportional increase of VEGF upstream regulators, HIF-1α and HO-1, was also observed. T. gondii induced the activation of host p-AKT, p-ERK1/2, and p-p38 MAPK in ARPE-19 cells in a parasite-burden dependent manner. However, VEGF expression decreased after the pre-treatment with PI3K inhibitors (LY294002 and GDC-0941), ERK1/2 inhibitor (PD098059), and p38 MAPK inhibitor (SB203580), but not JNK inhibitor (SP600125), in a dose-dependent manner. The anti-VEGF agent bevacizumab or VEGF siRNA transfection prominently inhibited the activation of p-AKT and p-ERK1/2, but not p-p38 MAPK and JNK1/2 in T. gondii-infected ARPE-19 cells. Bevacizumab treatment or VEGF siRNA transfection significantly inhibited the proliferation of T. gondii tachyzoites in the host cell, dose-dependently, but not invasion of parasites. VEGF-receptor 2 (VEGF-R2) antagonist, SU5416, attenuated VEGF production and tachyzoite proliferation in T. gondii-infected ARPE-19 cells in a dose-dependent manner. Collectively, T. gondii prominently induces VEGF production in ARPE-19 cells, and VEGF and AKT/ERK1/2 signaling pathways mutually regulate each other in T. gondii-infected ARPE-19 cells, but not p38 MAPK and JNK1/2 signaling pathways. VEGF and VEGF-R2 control the parasite proliferation in T. gondii-infected ARPE-19 cells. From this study, we revealed the putative mechanisms for VEGF induction as well as the existence of positive feedback between VEGF and PI3K/MAPK signaling pathways in T. gondii-infected retinal pigment epithelium.

Overlapping Spectrum of Retinochoroidal Scarring in Congenital Zika Virus and Toxoplasmosis Infections

BACKGROUND AND OBJECTIVE

Antenatal Zika virus (ZIKV) or toxoplasmosis infections may present with isolated eye abnormalities with absence of other apparent birth defects. The purpose of this article is to discuss the overlapping spectrum of clinical presentation and retinochoroidal scarring in congenital ZIKV and toxoplasmosis infections.

PATIENTS AND METHODS

Prenatal ultrasound abnormalities seen from antenatal ZIKV and toxoplasmosis infections overlap and may include intracranial calcifications, microcephaly, and intrauterine growth restriction. The clinical spectrum of both infections in less severely affected infants and children may include nonspecific neurological impairment such as developmental delay and seizures.

RESULTS

Inherent limitations in serological testing pose additional barriers in establishing a diagnosis. Retinal pigment epithelium (RPE) mottling in ZIKV infection can occur in isolation or adjacent to retinochoroidal atrophy. In contrast, RPE mottling outside of the borders of retinochoroidal atrophy is not typically seen in toxoplasmosis. To date, postnatal reactivation of congenital eye lesions as seen in toxoplasmosis have not been reported with ZIKV infection.

CONCLUSIONS

As children infected with congenital ZIKV grow older, subclinical eye abnormalities may be indistinguishable from toxoplasmosis. Brazil has had high prevalence of both diseases with long-term information available on toxoplasmosis only. Surveillance guidelines for asymptomatic eye abnormalities will likely evolve. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:779-784.].

The Role of Decidual PD-1+ Treg Cells in Adverse Pregnancy Outcomes due to Toxoplasma gondii Infection

Toxoplasma gondii infection during pregnancy can result in adverse pregnancy outcomes. Previously, we have reported that these outcomes are associated with the impaired function of decidual Treg cells; however, the detailed mechanisms involved were unclear. It has been reported that the suppressive capacity of Treg cells is dependent on PD-1 expression. The present study explored the role of decidual PD-1⁺ Treg cell function in adverse pregnancy outcomes due to T. gondii infection. Toxoplasma gondii-infected pregnant mice were sacrificed on gestational day 14 and their pregnancy outcomes were observed. The expression of PD-1 on decidual Treg cells and expressions of Foxp3, CTLA-4, TGF-β, and IL-10 on decidual PD-1⁺ and PD-1^- Treg cells were determined using flow cytometry. The results showed that the expression of PD-1 on decidual Treg cells was clearly higher in the T. gondii-infected mice than in the normal mice. Meanwhile, the expressions of Foxp3, CTLA-4, TGF-β, and IL-10 on decidual PD-1⁺ Treg cells were higher in the infected mice than in the normal mice. The expressions were higher in decidual PD1⁺ Treg cells than in PD-1^- Treg cells in the infected mice. However, these expressions on PD-1^- Treg cells did not significantly differ between the infected and normal mice. Nonetheless, the absolute percentages of decidual PD-1⁺ Treg cells decreased significantly in the infected mice compared with those in the normal mice. These results suggest that T. gondii infection mainly influences the function of decidual PD-1⁺ Treg cells, which would result in an insufficiently immunotolerant microenvironment and consequently in adverse pregnancy outcomes.

Management of Intraocular Infections in HIV

Purpose: Overview of treatment options for the most common intraocular opportunistic infections in patients with acquired immunodeficiency syndrome (AIDS), including ocular syphilis, ocular tuberculosis, toxoplasmic chorioretinitis, and viral retinitis. Method: Narrative Review. Results: Despite the huge advances in the development of combined antiretroviral therapy (cART) for the management of patients with human immunodeficiency virus (HIV) infection, opportunistic infections still represent a significant diagnostic dilemma and cause of ocular morbidity in patients with HIV. Conclusion: Although the treatment of intraocular infections in patients with AIDS may be challenging, prompt assessment of the clinical features and appropriate aggressive management of the underlying etiology are critical to avoid life and vision threatening.

Ocular toxoplasmosis associated with up-regulation of miR-155-5p/miR-29c-3p and down-regulation of miR-21-5p/miR-125b-5p

Ocular toxoplasmosis (OT) is one of the most common manifestations of Toxoplasma gondii infection and can be related with congenital or acquired infections. OT cause posterior uveitis that cause serious sequelae as complete loss of vision. microRNAs (miRNAs) are small non-coding RNAs, which have regulatory roles in cells by silencing messenger RNA. This study evaluated gene expression of miR-155-5p, miR-146a-5p, miR-21-5p, miR-29c-3p and miR-125b-5p in plasma of 51 patients with ocular toxoplasmosis (OT Group), 26 individuals with asymptomatic toxoplasmosis (AT Group), and 25 healthy individuals seronegative for toxoplasmosis (NC Group). Peripherical blood samples were collected in tube with EDTA for plasma isolation, laboratorial diagnosis for toxoplasmosis and RNA extraction. miRNA expression of each sample was performed by qPCR and values were expressed in Relative Quantification (RQ). Results showed that miR-155-5p and miR-29c-3p were up-expressed in OT patients than AT individuals. On the other hand, miR-21-5p and miR-125b-5p were down-expressed in OT patients. Differences were statistically significant. miR-146a-5p expression was similar in OT patients and AT individuals, without significant difference. In addition, comparative analysis for miRNA levels between AT and OT groups confirms these results. So far, this is the first study to evaluate circulating miRNA levels in ocular toxoplasmosis. These findings may contribute to further studies evaluating the exact role of these miRNAs in the course of infection, which may help in understanding the complex parasite-host interaction and future use in diagnosis, prognosis and therapeutic control in ocular toxoplasmosis.

Serological and molecular approaches in clinical diagnosis of ocular toxoplasmosis in Iran

Background:Toxoplasma gondii (T. gondii) is the most common parasite that can lead to a disease called toxoplasmosis. In this study, serological and molecular complementary tests have been conducted to detect or diagnose this parasite.

Methods: A total of 71 patients with clinical symptoms of ocular toxoplasmosis and 20 patients with other ocular infections were evaluated. Serum and buffy coat samples were collected and tested using enzyme-linked immunosorbent assay (ELISA) and nested polymerase chain reaction (nPCR) assessments. Superficial T. gondii B1 gene was evaluated in PCR. The ocular toxoplasmosis patients were followed-up 2 weeks after the first sampling and 4 weeks following the first laboratory testing. The main outcome measures were the efficiency of the diagnostic procedure and positive and negative predictive values (PPV and NPV).

Results: Overall, of the samples, 69% were PCR+, IgG+, and IgM-, and 4.2% showed PCR+, IgG+, and IgM+. In the first follow-up, after 2 weeks, from the 41 referred patients, 29 (70%) showed PCR+, IgG+, and IgM-, which confirmed the results of the first sampling. In the second follow-up, 9 (47%) patients were PCR+, IgG+, and IgM-. A correlation was observed between the first referral and the follow-ups. Also, from 71 patients, diagnosed clinically as ocular toxoplasmosis, the disease was confirmed in 73.2% and 26.8% of those suffering from other ocular infections. Of the 20 control group samples, 55% showed PCR-, IgG+, and IgM-. The sensitivity, specificity, negative and positive predictive values, and negative and positive likelihoods were analyzed for IgG and IgM antibodies and for PCR using ELISA method.

Conclusion: As the ophthalmologic signs of T. gondii may be mimicked by other infections, clinical methods may be complemented by laboratory approaches for a definite diagnosis. This would assist clinicians to achieve timely diagnosis and successful therapy and to control the infection.

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.

Role of Toxoplasma gondii Chloroquine Resistance Transporter in Bradyzoite Viability and Digestive Vacuole Maintenance

Toxoplasma gondii is a ubiquitous pathogen that can cause encephalitis, congenital defects, and ocular disease. T. gondii has also been implicated as a risk factor for mental illness in humans. The parasite persists in the brain as slow-growing bradyzoites contained within intracellular cysts. No treatments exist to eliminate this form of parasite. Although proteolytic degradation within the parasite lysosome-like vacuolar compartment (VAC) is critical for bradyzoite viability, whether other aspects of the VAC are important for parasite persistence remains unknown. An ortholog of Plasmodium falciparum chloroquine resistance transporter (CRT), TgCRT, has previously been identified in T. gondii To interrogate the function of TgCRT in chronic-stage bradyzoites and its role in persistence, we knocked out TgCRT in a cystogenic strain and assessed VAC size, VAC digestion of host-derived proteins and parasite autophagosomes, and the viability of in vitro and in vivo bradyzoites. We found that whereas parasites deficient in TgCRT exhibit normal digestion within the VAC, they display a markedly distended VAC and their viability is compromised both in vitro and in vivo Interestingly, impairing VAC proteolysis in TgCRT-deficient bradyzoites restored VAC size, consistent with a role for TgCRT as a transporter of products of digestion from the VAC. In conjunction with earlier studies, our current findings suggest a functional link between TgCRT and VAC proteolysis. This study provides further evidence of a crucial role for the VAC in bradyzoite persistence and a new potential VAC target to abate chronic Toxoplasma infection.IMPORTANCE Individuals chronically infected with the intracellular parasite Toxoplasma gondii are at risk of experiencing reactivated disease that can result in progressive loss of vision. No effective treatments exist for chronic toxoplasmosis due in part to a poor understanding of the biology underlying chronic infection and a lack of well-validated potential targets. We show here that a T. gondii transporter is functionally linked to protein digestion within the parasite lysosome-like organelle and that this transporter is necessary to sustain chronic infection in culture and in experimentally infected mice. Ablating the transporter results in severe bloating of the lysosome-like organelle. Together with earlier work, this study suggests the parasite's lysosome-like organelle is vital for parasite survival, thus rendering it a potential target for diminishing infection and reducing the risk of reactivated disease.

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.

Prevalence of antibody seroconversion to Toxoplasma gondii in uveitis and non-uveitis dogs

Objectives

To evaluate the prevalence of seroconversion to Toxoplasma gondii in dogs with uveitis and dogs without uveitis.

Methods

In total, 135 dogs were evaluated: 51 dogs were diagnosed with uveitis, and 84 dogs were without uveitis. Latex agglutination tests were performed on all sera, and the results were evaluated.

Results

Overall, 7.8 and 6.0 per cent of sera were positive for the presence of anti-T gondii antibodies (dilution ≥1:64) in the groups with uveitis and non-uveitis dogs, respectively. The frequency distribution of variables (positive and negative results in the uveitis and the non-uveitis group of dogs) was tested with Fisher’s exact test. There was no statistically significant difference between groups (P=0.73).

Clinical significance

These findings suggest that evidence of exposure to T gondii was not significantly different between uveitis and non-uveitis groups of dogs and that the possible association between exposure to T gondii and canine uveitis requires further investigation. This study is the first to report the seroprevalence of anti-T gondii antibodies in dogs in the UK population and the first to report the seroprevalence of anti-T gondii antibodies in dogs with uveitis.

Effectiveness of Treatments for Ocular Toxoplasmosis

Purpose: To evaluate the effectiveness of treatments for ocular toxoplasmosis (OT).Methods: A review of charts was conducted from patients who experienced an active episode of OT treated at the Federal University of São Paulo and associated sites. OT charts were reviewed to determine treatment effectiveness based on clinical judgment, taking clinical course and outcome into consideration in addition to change in best-corrected visual acuity. Treatment emergent adverse events (TEAEs) were used to assess safety.Results: Overall, 451/1200 patient charts met the inclusion criteria. The most commonly prescribed treatment was trimethoprim + sulfamethoxazole (52.3%) followed by pyrimethamine + sulfadiazine (28%). Treatment was successful in 96.9% of patients. Irrespective of the treatment, active lesions were resolved in 63.9% of patients within 6 weeks. Vision improved in 56.3% of patients. The incidence of TEAEs was low (10%).Conclusions: All treatments were effective for active episodes of OT, with few side effects.

Toxoplasma gondii bradyzoites and tachyzoites isolation from vitreous of atypical necrotizing retinitis

BACKGROUND

Detection of Toxoplasma gondii cysts in vitreous of immunocompetent patient with necrotizing retinitis is extremely rare. We herein report the isolation of Toxoplasma bradyzoites and tachyzoites from the vitreous of healthy person.

RESULTS

A 19-year-old immunocompetent female presented with sudden loss of vision in left eye since 1 week. The BCVA was 6/6 and HM in right and left eye. The left eye finding was suggestive of diffuse necrotizing retinitis with retinal detachment. The IgM and IgG for TORCH infection were negative and HIV, HCV and HBsAg tests were also non reactive. The patient underwent diagnostic and therapeutic vitrectomy with silicon oil installation. The vitreous toxoplasma IgG titre was found to be significantly raised to 1:16. Bradyzoites of toxoplasma were identified in H&E staining and tachyzoites of Toxoplasma were identified in Giemsa staining of vitreous sample. She received oral clindamycin and oral corticosteroid but the vision could not be restored in left eye.

CONCLUSION

Hence, atypical toxoplasmosis with necrotizing retinitis is a fulminant condition with the diagnostic and therapeutic challenge.

An updated literature review on maternal-fetal and reproductive disorders of Toxoplasma gondii infection

BACKGROUND

Toxoplasma gondii infection is one of the most prevalent infectious disease with worldwide distribution. Congenital toxoplasmosis is annually responsible for 1.20 million disability-adjusted life years around the world, but often it is overlooked many countries.

METHODS

We performed an updated review to summarize the current researches on fetal, neonatal and maternal consequences of T. gondii infection and also adverse effects of toxoplasmosis on women reproductive organs.

RESULTS

T. gondii infection could be cause of several abnormalities from hydrocephalus, microcephaly, deafness, abortion and still birth in fetal to psychomotor retardation, intellectual disability, hearing loss, slower postnatal motor development during the first year of life; and chorioretinitis, cryptogenic epilepsy and autism spectrum disorders in newborns. Moreover, this infection is related with neuropsychiatric disorders such as anxiety, schizophrenia spectrum disorders, depression, decreased weight, autoimmune thyroid diseases, self-directed violence, violent suicide attempts in mothers. This literature review emphasized that toxoplasmosis could be an important neglected factor endometritis, ovarian dysfunction, impaired folliculogenesis, ovarian and uterine atrophy, decrease in reproductive organs weight and reproductive performance in women. We reviewed role of the immunological profile such as pro-infiammatory cytokines and hormonal changes as main potential mechanisms related to this infection and development of maternal-fetal and reproductive disorders.

CONCLUSION

T. gondii is associated with several brain related disorders in both mothers and newborns, and also it is cause of several abnormalities in reproductive organs. Early diagnosis and treatment of the infection could be effective to significantly improve the clinical outcome.

Post-prophylaxis Toxoplasma chorioretinitis following donor-recipient mismatched liver transplantation

Toxoplasmosis may be transferred by organ transplantation. The most common clinical presentation is with multisystem disease, although isolated ocular toxoplasmosis has been described. Many centers have suggested that universal use of co-trimoxazole prophylaxis obviates the need for specific Toxoplasma testing. We report a case of donor-acquired ocular toxoplasmosis after liver transplantation despite co-trimoxazole prophylaxis. The diagnosis was confirmed by Toxoplasma polymerase chain reaction assay in conjunction with seroconversion. The fact that the infection was donor acquired was confirmed by serological mismatch and the absence of sporozoite-specific antigen antibody in the recipient.

Characterization of the parasite-induced lesions in the posterior segment of the eye

Ocular lesions are frequently associated with different parasitic infections. The classes of infection include protozoa, nematodes, cestodes, and ectoparasites. Ocular parasitic infections can manifest in any part of the eye; the disease manifestations are frequently characterized as either posterior or anterior eye disease. Parasite-induced lesions may be due to damage directly caused by the parasite, indirect pathology caused by toxic products or the immune response initiated by infectious parasitism. This review characterized the parasite-induced lesions in the posterior segment of the eye. Prompt diagnosis and early treatment of these lesions can reduce ocular morbidity. The method of the literature search was conducted on PubMed, Elsevier Scopus database, and Google Scholar with no limitation on the year of publication databases. It was limited to English articles published for ocular lesions in clinical studies and was focused on parasitic infections of the eye.

Serum levels of neurotrophic factors in active toxoplasmic retinochoroiditis

Toxoplasmic retinochoroiditis (TR) is the most common identifiable cause of posterior uveitis in Brazil. Response to treatment and clinical presentation may vary significantly. We assessed serum levels of brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), nerve growth factor (NGF), neurotrophin (NT)-3, and NT-4/5 in patients with active TR, before and after TR treatment.

Methods

Twenty patients with active lesion and 15 healthy controls were enrolled in the study. Serum concentration of neurotrophic factors was determined by enzyme-linked immunosorbent assay.

Results

BDNF levels were significantly higher in patients before treatment when compared with controls (p = 0.0015). There was no significant difference in pro-BDNF, NGF, GDNF, NT-3, and NT-4/5 levels between TR patients and controls. Treatment did not affect the levels of these factors.

Conclusion

BDNF may be released in the context of the active TR inflammatory response.

Ocular Autoimmune Systemic Inflammatory Infectious Study (OASIS) - Report 1: Epidemiology and Classification

PURPOSE

To report the epidemiology and classification of ocular inflammation at a tertiary eye care center in Singapore.

METHODS

Retrospective cohort study of the clinical records of consecutive new cases from the Ocular Autoimmune Systemic Inflammatory Infectious Study (OASIS) database from 2004-2015.

RESULTS

A total of 2200 patients were studied from the OASIS database. The most common anatomic diagnosis was anterior uveitis (55.9%), posterior uveitis (17.5%), panuveitis (9.6%), and intermediate uveitis (4.7%). In addition, scleritis (6.1%), keratouveitis (2.8%), retinal vasculitis (2.2%), and episcleritis (1.2%) were observed. Etiology was established in 65.1%, with 35.2% of patients associated with non-infectious etiologies. The most common etiologies found were presumed tuberculosis (7.2%), followed by cytomegalovirus infection (6.9%), herpetic infection (6.3%), HLA-B27-associated anterior uveitis (4.2%), and ankylosing spondylitis (3.8%).

CONCLUSIONS

The pattern of ocular inflammation in Singapore has similarities with both Western and Asian populations. Anterior uveitis was the most common, with non-infectious etiologies being slightly more common than infectious etiologies.

Trimethoprim-Sulfamethoxazole Versus Placebo in Reducing the Risk of Toxoplasmic Retinochoroiditis Recurrences: A Three-Year Follow-up

PURPOSE

To compare the effects of 1 year of treatment with trimethoprim/sulfamethoxazole (TMP-SMZ) vs a placebo in reducing the risk of toxoplasmic retinochoroiditis recurrences during a 3-year follow-up period.

DESIGN

Randomized, double-masked clinical trial.

METHODS

This cohort included 141 volunteers recruited in Campinas, Brazil. Inclusion criterion was unilateral active recurrent toxoplasmic retinochoroiditis. All volunteers were treated with 1 tablet of TMP-SMZ (160 mg/800 mg) twice daily for 45 days, and all lesions healed after this treatment. After this initial treatment, the volunteers were randomly assigned to Group 1 (1 TMP-SMZ tablet every 2 days for 311 days) or Group 2 (1 identical placebo tablet containing starch with no active ingredients every 2 days for 311 days). At the second- and third-year follow-up appointments, none of the volunteers received treatment unless a new recurrence episode had occurred. The primary outcomes were recurrent toxoplasmic retinochoroiditis within the first year of follow-up and recurrent toxoplasmic retinochoroiditis within the third year of follow-up.

RESULTS

The cumulative probability of recurrence at 1, 2, and 3 years of follow-up were, respectively, 13.0% (9/69), 17.4% (12/69), and 20.3% (14/69) in the placebo group and 0% (0/72) in the TMP-SMZ group (P < .001, log-rank test). There was no case of multiple recurrences in the same individual. No treatment-limiting toxicity or side effects were observed in either group. New recurrences were more frequent among female volunteers.

CONCLUSIONS

TMP-SMZ may be used safely for prophylaxis of recurrent toxoplasmic retinochoroiditis, with long-term benefits.

Current Practices in Ocular Toxoplasmosis: A Survey of Brazilian Uveitis Specialists

PURPOSE

To describe treatment practices for ocular toxoplasmosis among members of the Brazilian Uveitis Society.

METHODS

An online questionnaire sent to specialists, between October 2014 and March 2015.

RESULTS

Most respondents (67.9%) treat all active cases. Most specialists consider visual acuity <20/200 (88.2%), severe vitreous inflammation (94.1%), and ocular disease during acquired infection (88.2%) as absolute indications for treatment. Systemic steroids are associated with anti-toxoplasmic therapy in most cases by 50.9% of the respondents. For immunocompetent individuals, 57.4% of the respondents chose trimethoprim/sulfamethoxazole. Classical therapy (sulfadiazine/pyrimethamine) is preferred most for patients with central lesions (70.4%), immunosuppression (68.4%), acquired infection (70.4%), and atypical forms (74.1%). For patients with frequent relapses, 84.9% of the respondents preferred antibiotic prophylaxis.

CONCLUSIONS

Treatment patterns of ocular toxoplasmosis are not uniform among Brazilian specialists. Most specialists treat all cases of active retinochoroiditis. Typical cases are more frequently treated with trimethoprim/sulfamethoxazole. However, classical therapy is the regimen of choice when lesions are considered more severe.

The Impact of Short-Term, Intensive Antifolate Treatment (with Pyrimethamine and Sulfadoxine) and Antibiotics Followed by Long-Term, Secondary Antifolate Prophylaxis on the Rate of Toxoplasmic Retinochoroiditis Recurrence

PURPOSE

To assess the impact of intensive antifolate treatment, followed by secondary antifolate prophylaxis (A-SP) on the recurrence rate of toxoplasmic retinochoroiditis (TRC). To investigate whether there are any other factors potentially predisposing for recurrence.

MATERIAL AND METHODS

A total of 637 medical records of TRC patients, who had been treated in the years 1994-2013 were reviewed. All patients were treated with pyrimethamine /sulfadoxine one 25mg/500mg tablet daily (P/S 25/500mg) for 21 days with a double loading dose for the first two days. From Day 2 the patients also received prednisone at a starting dose of 40mg and spiramycine 3 million IU three times daily, given for 10 days followed by azithromycin 500mg once daily for another 6 days. The analysis of the recurrence rate involved 352 patients who had completed 6-month secondary prophylaxis (P/S one 25 mg/500mg tablet twice a week).

RESULTS

When secondary antifolate prophylaxis (A-SP) was instituted immediately after the treatment for TRC, the probability of 3-year recurrence-free survival after the first course of A-SP was 90.9%. A recurrence was most likely approximately 3.5 years after the first treatment. A univariate Cox regression model demonstrated that a risk for recurrence was 2.82 times higher (p = 0.02) in patients with retinal scars. In the multivariate analysis, the risk for recurrence was 2.41 higher (p = 0.06). In patients with haemorrhagic lesions the risk for recurrence was lower, aRR = 0.17 (approaching borderline statistical significance p = 0.08).

CONCLUSIONS

With the institution of A-SP of immediately after the intensive treatment for TRC, i.e. when a reactivation was most likely, there was no recurrence during A-SP. Following A-SP the recurrence rates were low and recurrence-free periods tended to be longer. The treatment regimen employed had a beneficial effect on the recurrence interval as it reduced and delayed the highest probability of recurrence.

Effect ofToxoplasma gondiiinfection on the junctional complex of retinal pigment epithelial cells

Ocular toxoplasmosis is the most frequent cause of uveitis, leading to partial or total loss of vision, with the retina the main affected structure. The cells of the retinal pigment epithelium (RPE) play an important role in the physiology of the retina and formation of the blood–retinal barrier. Several pathogens induce barrier dysfunction by altering tight junction (TJ) integrity. Here, we analysed the effect of infection byToxoplasma gondiion TJ integrity in ARPE-19 cells. Loss of TJ integrity was demonstrated inT. gondii-infected ARPE-19 cells, causing increase in paracellular permeability and disturbance of the barrier function of the RPE. Confocal microscopy also revealed alteration in the TJ protein occludin induced byT. gondiiinfection. Disruption of junctional complex was also evidenced by scanning and transmission electron microscopy. Cell–cell contact loss was noticed in the early stages of infection byT. gondiiwith the visualization of small to moderate intercellular spaces. Large gaps were mostly observed with the progression of the infection. Thus, our data suggest that the alterations induced byT. gondiiin the structural organization of the RPE may contribute to retinal injury evidenced by ocular toxoplasmosis.

Experimental Models of Ocular Infection with Toxoplasma Gondii

Ocular toxoplasmosis is a vision-threatening disease and the major cause of posterior uveitis worldwide. In spite of the continuing global burden of ocular toxoplasmosis, many critical aspects of disease including the therapeutic approach to ocular toxoplasmosis are still under debate. To assist in addressing many aspects of the disease, numerous experimental models of ocular toxoplasmosis have been established. In this article, we present an overview on in vitro, ex vivo, and in vivo models of ocular toxoplasmosis available to date. Experimental studies on ocular toxoplasmosis have recently focused on mice. However, the majority of murine models established so far are based on intraperitoneal and intraocular infection with Toxoplasma gondii. We therefore also present results obtained in an in vivo model using peroral infection of C57BL/6 and NMRI mice that reflects the natural route of infection and mimics the disease course in humans. While advances have been made in ex vivo model systems or larger animals to investigate specific aspects of ocular toxoplasmosis, laboratory mice continue to be the experimental model of choice for the investigation of ocular toxoplasmosis.

A novel dynamic flow immunochromatographic test (DFICT) using gold nanoparticles for the serological detection of Toxoplasma gondii infection in dogs and cats

A novel dynamic flow immunochromatographic test (DFICT) is proposed for rapid assay utilizing Toxoplasma gondii as a model. The test is based on a proprietary technology that combines the principles of immunochromatography and fluid dynamics. Gold nanoparticles conjugated to staphylococcal protein A (SPA) were prepared in liquid form and used as signal vehicles. T. gondii-specific recombinant antigens and SPA were sprayed onto a nitrocellulose membrane in strips at positions designated as T and C, respectively. The DFICT is performed by applying a 100 µL aliquot of liquid gold-SPA conjugate to the reagent hole and a 5 μL aliquot of serum sample to the sample hole. The results were observable within 5 min by the naked eye. The lowest detectable limit of the assay was determined as the highest dilution (1:320) of positive serum. No cross-reaction of the antibodies with other related canine or feline pathogens was observed. The DFICT can be stored for 12 months at 4 °C or 6 months with no loss of sensitivity or specificity. A high degree of consistency was observed between the DFICT and the standard ELISA kit, supporting the reliability of the novel test strip. The introduction of a liquid gold nanoparticle conjugate reagent provides this method with several attractive characteristics, such as ease of manufacture, low sample volume requirements, high selectivity and high efficiency. This method opens a novel pathway for rapid diagnostic screening and field analysis.

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A novel dynamic flow immunochromatographic test (DFICT) is developed.

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A liquid gold nanoparticle conjugate reagent is introduced in DFICT.

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It is not necessary to prepare the conjugated pad and the sample pad in DFICT.

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DFICT requires only 5 μL of serum sample with no need for sample pretreatment.

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DFICT can be used for serological detection of T. gondii in both dogs and cats.