Epidemiology, pathophysiology, and the future of ocular toxoplasmosis

Ocular Toxoplasmosis: Advances in Toxoplasma gondii Biology, Clinical Manifestations, Diagnostics, and Therapy

Toxoplasma gondii, an obligate intracellular parasite, is a globally prevalent pathogen capable of infecting a wide range of warm-blooded animals, including humans. Ocular toxoplasmosis (OT), a severe manifestation of T. gondii infection, can lead to potentially blinding complications. This comprehensive review delves into the current understanding of T. gondii biology, exploring its complex life cycle, diverse transmission routes, and strain diversity. This article provides an in-depth analysis of the clinical manifestations of OT, which can result from both congenital and acquired infections, presenting a spectrum of signs and symptoms. The review examines various diagnostic strategies employed for OT, including clinical examination, multimodal imaging techniques such as fundus fluorescein angiography (FFA), indocyanine green angiography (ICGA), optical coherence tomography (OCT), and optical coherence tomography angiography (OCTA), as well as laboratory tests including serology and molecular methods. Despite extensive research, the specific mechanisms underlying ocular involvement in T. gondii infection remain elusive, and current diagnostic options have limitations. Moreover, the treatment of active and recurrent OT remains a challenge. While existing therapies, such as antimicrobial agents and immunosuppressants, can control active infections, they do not offer a definitive cure or completely prevent recurrence. The clinical endpoints for the management of active and recurrent OT are also not yet well-established, and the available treatment methods carry the potential for adverse effects. This article highlights the need for future research to elucidate the pathogenesis of OT, investigate genetic factors influencing susceptibility to infection, and develop more sensitive and specific diagnostic tools. Enhancing global surveillance, implementing robust prevention strategies, and fostering multidisciplinary collaborations will be crucial in reducing the burden of OT and improving patient outcomes. This comprehensive review aims to provide a valuable resource for clinicians, researchers, and policymakers, contributing to a better understanding of T. gondii infection and its impact on ocular health.

Genetic Variations in the Purinergic P2X7 Receptor Are Associated with the Immune Response to Ocular Toxoplasmosis in Colombia

Ocular toxoplasmosis (OT) is characterized by inflammation within the eye and is the most recognized clinical manifestation of toxoplasmosis. The objective of this study was to identify new single-nucleotide polymorphisms (SNPs) in the P2RX7 gene that may have significance in the immune response to OT in Colombian patients. A case-control study was conducted to investigate the associations between SNPs (rs1718119 and rs2230912) in the P2RX7 gene and OT in 64 Colombian patients with OT and 64 controls. Capillary electrophoresis was used to analyze the amplification products, and in silico algorithms were employed to predict deleterious SNPs. Stability analysis of amino acid changes indicated that both mutations could lead to decreased protein structure stability. A nonsynonymous SNP, Gln460Arg, located in the long cytoplasmic tail of the receptor, showed a significant association with OT (Bonferroni correction (BONF) = 0.029; odds ratio OR = 3.46; confidence interval CI: 1.05 to 11.39), while no significant association between rs1718119 and OT risk was observed. Based on the 3D structure analysis of the P2RX7 protein trimer, it is hypothesized that an increase in the flexibility of the cytoplasmic domain of this receptor could alter its function. This SNP could potentially serve as a biomarker for identifying Colombian patients at risk of OT.

Clinical Features and Possible Origin of Preretinal Deposits in Different Ocular Diseases and Events: A Narrative Review

Preretinal deposits (PDs) are a rare condition among fundus diseases. We found that preretinal deposits have some features in common that can provide clinical information. This review affords an overview of PDs in different but related ocular diseases and events, and summarizes the clinical features and possible origin of PDs in related conditions, providing diagnostic clues for ophthalmologists when facing PDs. A literature search was performed using three major electronic databases (PubMed, EMBASE, and Google Scholar) to identify potentially relevant articles published on or before June 4, 2022. Most of the cases in the enrolled articles had optical coherence tomography (OCT) images to confirm the preretinal location of the deposits. Thirty-two publications reported PD-related conditions, including ocular toxoplasmosis (OT), syphilitic uveitis, vitreoretinal lymphoma, human T-cell lymphotropic virus type 1 (HTLV-I) associated uveitis or HTLV-I carriers, acute retinal necrosis, endogenous fungal endophthalmitis, idiopathic uveitis, and exogenous materials. Based on our review, OT is the most frequent infectious disease to exhibit PDs, and silicone oil tamponade is the most common exogenous cause of preretinal deposits. PDs in inflammatory diseases are highly suggestive of active infectious disease and are preferentially accompanied by a retinitis area. However, PDs will largely resolve after etiological treatment in either inflammatory or exogenous conditions.

In vitro and in vivo anti−Toxoplasma activities of HDAC inhibitor Panobinostat on experimental acute ocular toxoplasmosis

Ocular toxoplasmosis (OT) is retinochoroiditis caused by Toxoplasma gondii infection, which poses a huge threat to vision. However, most traditional oral drugs for this disease have multiple side effects and have difficulty crossing the blood-retinal barrier, so the new alternative strategy is required to be developed urgently. Histone deacetylases (HDAC) inhibitors, initially applied to cancer, have attracted considerable attention as potential anti-Toxoplasma gondii drugs. Here, the efficacy of a novel HDAC inhibitor, Panobinostat (LBH589), against T. gondii has been investigated. In vitro, LBH589 inhibited the proliferation and activity of T. gondii in a dose-dependent manner with low toxicity to retinal pigment epithelial (RPE) cells. In vivo, optical coherence tomography (OCT) examination and histopathological studies showed that the inflammatory cell infiltration and the damage to retinal architecture were drastically reduced in C57BL/6 mice upon treatment with intravitreal injection of LBH589. Furthermore, we have found the mRNA expression levels of inflammatory cytokines were significantly decreased in LBH589–treated group. Collectively, our study demonstrates that LBH589 holds great promise as a preclinical candidate for control and cure of ocular toxoplasmosis.

Distinguishing swept-source optical coherence tomography findings in active toxoplasmic retinochoroiditis

OBJECTIVE

To define the swept-source optical coherence tomography (SS-OCT) features which distinguish ocular toxoplasmosis (OT) from other forms of retinochoroiditis.

METHODS

This is a prospective diagnostic study enrolling 43 eyes of 43 patients with active toxoplasmic (TOXO) retinochoroiditis matched to 54 eyes (54 lesions) with non-TOXO retinochoroiditis evaluated by structural SS-OCT.

RESULTS

The finding of retinal hyper-reflective round deposits, sub-lesional choroidal thickening, and sub-lesional retinal pigment epithelium elevation were more likely to be found in TOXO lesions with a positive likelihood ratio of 45.2 (95% CI: 6.45-316.56), 23.86 (95% CI: 6.09-93.36), and 9.79 (95% CI: 4.22-22.7), respectively. The presence of each of these findings was associated with a high level for positive predictive value (PPV) (88.63-97.29), negative predictive value (NPV) (88.3-92.45), sensitivity (83.72-90.69), and specificity (90.74-98.14). Two-parameter model binary logistic regression suggested that sub-lesional retinal pigment epithelium elevation and sub-lesional choroidal thickening were significant predictors of the diagnosis of OT (Wald = 11.905, p < 0.001; Wald = 14.881, p < 0.001; respectively). By adding hyper-reflective round deposits along the posterior hyaloid or the retinal surface the model improved its performance with very good diagnostic accuracy with area under the curve (AUC) values of 0.96 (95% CI: 0.9-0.99) for two parameters model and 0.98 (95% CI: 0.93-0.99) for the three parameters model.

CONCLUSIONS

Our results show that three OCT findings including retinal hyper-reflective round deposits, sub-lesional choroidal thickening, and sub-lesional retinal pigment epithelium elevation are more likely to occur in OT patients as compared with non-OT patients.

Vision-Related Quality Of Life And Depression In Brazilian Patients With Toxoplasmic Retinochoroiditis

PURPOSE

To investigate visual-related quality of life (VRQL) and prevalence and severity of depressive symptoms in Brazilian individuals with toxoplasmic retinochoroiditis (TRC).

DESIGN

Comparative observational cross-sectional study. The National Eye Institute Visual Function Questionnaire-25 (NEI-VFQ-25) and Beck Depression Inventory-II (BDI-II) were applied to respectively assess VRQL and depression in individuals consecutively seen at a uveitis referral center. Clinical/demographical data were collected. Descriptive/analytic statistics were employed, with P<0.05.

RESULTS

Patients and controls were comparable concerning age, sex and socioeconomic level. VRQL scores for all subscales were significantly lower in TRC when compared with controls, particularly associated (P<0.05) with female sex, history of ≥2 prior TRC recurrences, concomitant use of systemic corticosteroids, monocular vision and blindness. Depressive symptoms were more prevalent in TRC (55/188; 29.2%) than in controls (34/182; 18.7%) (P=0.023), also being associated with lower VRQL scores (P<0.001). Seropositive and seronegative controls for toxoplasmosis had similar VRQL scores and comparable rates of depressive symptoms.

CONCLUSION

TRC affects VRQL in Brazilian individuals, particularly women, using systemic corticosteroids, with visual impairment and presenting recurrences of TRC. One-third of patients with TRC had evidence of depression, which was also associated with lower VRQL scores. Mental health issues in subjects with TRC should not be overlooked.

Association between ocular toxoplasmosis and APEX1 and MYD88 polymorphism

Ocular toxoplasmosis (OT) is the most common form of posterior uveitis, and in some countries, it is the most frequent cause of visual impairment. Studies demonstrate that the polymorphism in genes involved with the immune response can be related both to the occurrence and to the recurrence of OT. Thus, the present study aimed to analyze the association between OT and the polymorphism of the APEX1 (rs1130409) and MyD88 (rs7744) genes. The studied sample consisted of 48 volunteers with OT and 96 asymptomatic volunteers, but positive for anti - T. gondii IgG (control group). Blood collection was performed for serological analysis (ELISA) and DNA extraction. Genotyping of the polymorphism was performed using real-time PCR. To analyze the association between gene polymorphism and OT, logistic regression was performed. The results showed no association between the MYD88 gene polymorphism and the development of OT. However, a significant association was found between OT and APEX1 gene polymorphism, indicating that individuals expressing polymorphic (GG) or heterozygous (GT) alleles are more likely to develop the disease (P-value = 0.02 and 0.03 respectively). These results suggest that APEX1 (rs1130409) polymorphism is a risk factor for the occurrence of ocular toxoplasmosis in the studied population.

PRESUMED FOVEAL BACILLARY LAYER DETACHMENT IN A PATIENT WITH TOXOPLASMOSIS CHORIORETINITIS AND PACHYCHOROID DISEASE

PURPOSE

To report a detachment that apparently separated photoreceptor inner segment myoids from inner segment ellipsoids as a manifestation of toxoplasmosis chorioretinitis in a patient with pachychoroid spectrum disease.

METHODS

Multimodal imaging including fundus photography, spectral domain and enhanced-depth imaging optical coherence tomography (OCT), indocyanine green angiography, and OCT angiography.

RESULTS

A 33-year-old man with a history of toxoplasmosis chorioretinitis reported 1 week of decreased vision to 20/200 in his right eye. Examination of the right eye demonstrated mild vitritis with recurrent chorioretinitis inferior to the fovea and adjacent to a chorioretinal scar. A dome-shaped, foveal photoreceptor layer-splitting detachment was noted on OCT. Because degenerating cone photoreceptors are capable of shedding their inner segments, we inferred the location of the detachment at the level of the inner segment myoid and provided a histological example of such from an unrelated donor case. In addition, multimodal imaging revealed dilated choroidal veins (pachyvessels) with attenuation of the inner choroid in both eyes and asymptomatic findings of central serous chorioretinopathy in the left eye. After 1 month of antibiotic and steroid therapy, the chorioretinitis resolved, as did the detachment. Hyperreflective foci on the vitreoretinal interface were appreciated with en face OCT that appeared to aggregate throughout the course of therapy, induce inner retinal striae, and resolve without inducing epiretinal membrane formation.

CONCLUSION

Patients with preexisting pachychoroid spectrum disease may manifest a more significant retinal fluid accumulation in the setting of superimposed chorioretinal inflammation. In this case of macular toxoplasmosis chorioretinitis, inflammation manifested as a retinal detachment at the level of photoreceptor inner segment myoids that we named as a bacillary layer detachment. In this case, inflammatory sequelae of toxoplasmosis reactivation responded well to oral and intravitreal therapy.

Congenital ocular toxoplasmosis with torpedo maculopathy and retinopathy of prematurity in a premature baby

Purpose

To report an unusual case of congenital bilateral abnormality due to coexisting ocular toxoplasmosis and retinopathy of prematurity.

Observations

A prematurely born baby with bilateral retinopathy of prematurity (ROP) (one eye treated) was found to have a hyperpigmented torpedo maculopathy lesion in one eye while the other eye presented with microphthalmia, congenital cataract and non-specific pigmentary retinopathy. Following negative TORCH screening, laboratory tests subsequently revealed increased plasma IgG and IgM for toxoplasmosis.

Conclusions

We present an unusual case of coexistence of congenital ocular toxoplasmosis with torpedo maculopathy and retinopathy of prematurity.

Murine Model of Primary Acquired Ocular Toxoplasmosis: Fluorescein Angiography and Multiplex Immune Mediator Profiles in the Aqueous Humor

Purpose

To establish a murine model of primary acquired ocular toxoplasmosis (OT) and to investigate the immune mediator profiles in the aqueous humor (AH).

Methods

C57BL/6 mice were perorally infected with Toxoplasma gondii. The ocular fundus was observed, and fluorescein angiography (FA) was performed. The AH, cerebrospinal fluid (CSF), and serum were collected before infection and at 28 days post-infection (dpi); the immune mediator levels in these samples were analyzed using multiplex bead assay.

Results

Fundus imaging revealed soft retinochoroidal lesions at 14 dpi; many of these lesions became harder by 28 dpi. FA abnormalities, such as leakage from retinal vessels and dilation and tortuosity of the retinal veins, were observed at 14 dpi. Nearly all these abnormalities resolved spontaneously at 28 dpi. In the AH, interferon-γ, interleukin (IL)-1α, IL-1β, IL-6, IL-10, IL-12(p40), IL-12(p70), CCL2/MCP-1, CCL3/MIP-1α, CCL4/MIP-1β, CCL5/RANTES, and CXCL1/KC levels increased after infection. All these molecules except IL-1α, IL-4, and IL-13 showed almost the same postinfection patterns in the CSF as they did in the AH. The tumor necrosis factor α, IL-4, and IL-5 levels in the AH and CSF of the T. gondii–infected mice were lower than those in the serum. The postinfection IL-1α, IL-6, CCL2/MCP-1, CCL4/MIP-1β, and granulocyte colony-stimulating factor levels in the AH were significantly higher than those in the CSF and serum.

Conclusions

A murine model of primary acquired OT induced via the natural infection route was established. This OT model allows detailed ophthalmologic, histopathologic, and immunologic evaluations of human OT. Investigation of AH immune modulators provides new insight into OT immunopathogenesis.

Epidemiology of Uveitis in a tertiary care centre in Portugal

Purpose: Evaluate the prevalence and incidence, demographic characteristics, anatomical classification, concomitant complications and treatment of uveitis, as well as its association with systemic diseases in the northern Portuguese population referred to a tertiary care centre (São João Hospital, Porto).Methods: A retrospective observational study of 545 consecutive uveitis cases was performed between 12th April 2012 and the 26th October 2017. Uveitis was classified according to Standard Uveitis Nomenclature, while aetiology and complications were diagnosed by specific clinical and laboratory testing.Results: Prevalence was calculated to be 12,4 cases per 100,000 people while incidence was 3.9 cases per 100,000 people annual incidence. The ratio of females to males was 1.32:1 and the mean age at diagnosis was 47,86 years. Anterior uveitis was the most common classification making up 47.5%, followed by non-infectious posterior uveitis 18,0%, infectious posterior uveitis 8,4%, intermediate uveitis 5,5% and panuveitis 4,2%. Extra-uveal entities made up the rest of the causes (16.4%). In terms of aetiology, the majority of uveitis was idiopathic (32,1%) followed by axial spondylarthritis (12.1%), Behçet's disease (8,8%), sarcoidosis (6,1%), tuberculosis (5,5%), herpes (5,1%), toxoplasmosis (3,1%) among other less frequent causes.Conclusion: In our referral region, 72% of uveitis cases were correctly identified surpassing other studies. There was a higher rate of intermediate uveitis and lower number of panuveitis cases when compared to a previous Portuguese study. Extensive monitoring of the development of uveitis by international multicentre prospective studies could be useful for increasing practitioner awareness and diagnostic approach.

Recent Advances in Diagnosis and Treatment of Infectious Uveitis Prevalent in Asia-Pacific Region

ABSTRACT

The role of infections in intraocular inflammation is being increasingly recognized across the world. The Asia-Pacific region, being the single largest and most populous geographical entity on the planet, is home to a wide variety of such infections. Not surprisingly, there has been an explosion in the literature on infectious uveitis emerging from Asia-Pacific countries. In this review, we have covered recent advances in the diagnosis, treatment, and pathogenesis of common forms of infectious uveitis from the Asia-Pacific region. Much of the literature is focussed on the diagnosis of these infections by clinical criteria and laboratory investigations. There has also been an increased emphasis on the application of newer modes of ocular imaging and understanding pathomechanisms of ocular inflammation in these infections. Together this research has significantly improved our understanding of the diagnosis and management of infectious uveitis.

Implications of TORCH Diseases in Retinal Development-Special Focus on Congenital Toxoplasmosis

There are certain critical periods during pregnancy when the fetus is at high risk for exposure to teratogens. Some microorganisms, including Toxoplasma gondii, are known to exhibit teratogenic effects, interfering with fetal development and causing irreversible disturbances. T. gondii is an obligate intracellular parasite and the etiological agent of Toxoplasmosis, a zoonosis that affects one third of the world's population. Although congenital infection can cause severe fetal damage, the injury extension depends on the gestational period of infection, among other factors, like parasite genotype and host immunity. This parasite invades the Central Nervous System (CNS), forming tissue cysts, and can interfere with neurodevelopment, leading to frequent neurological abnormalities associated with T. gondii infection. Therefore, T. gondii is included in the TORCH complex of infectious diseases that may lead to neurological malformations (Toxoplasmosis, Others, Rubella, Cytomegalovirus, and Herpes). The retina is part of CNS, as it is derived from the diencephalon. Except for astrocytes and microglia, retinal cells originate from multipotent neural progenitors. After cell cycle exit, cells migrate to specific layers, undergo morphological and neurochemical differentiation, form synapses and establish their circuits. The retina is organized in nuclear layers intercalated by plexus, responsible for translating and preprocessing light stimuli and for sending this information to the brain visual nuclei for image perception. Ocular toxoplasmosis (OT) is a very debilitating condition and may present high severity in areas in which virulent strains are found. However, little is known about the effect of congenital infection on the biology of retinal progenitors/ immature cells and how this infection may affect the development of this tissue. In this context, this study reviews the effects that congenital infections may cause to the developing retina and the cellular and molecular aspects of these diseases, with special focus on congenital OT.

Pathogenesis of ocular toxoplasmosis

Ocular toxoplasmosis is a retinitis -almost always accompanied by vitritis and choroiditis- caused by intraocular infection with Toxoplasma gondii. Depending on retinal location, this condition may cause substantial vision impairment. T. gondii is an obligate intracellular protozoan parasite, with both sexual and asexual life cycles, and infection is typically contracted orally by consuming encysted bradyzoites in undercooked meat, or oocysts on unwashed garden produce or in contaminated water. Presently available anti-parasitic drugs cannot eliminate T. gondii from the body. In vitro studies using T. gondii tachyzoites, and human retinal cells and tissue have provided important insights into the pathogenesis of ocular toxoplasmosis. T. gondii may cross the vascular endothelium to access human retina by at least three routes: in leukocyte taxis; as a transmigrating tachyzoite; and after infecting endothelial cells. The parasite is capable of navigating the human neuroretina, gaining access to a range of cell populations. Retinal Müller glial cells are preferred initial host cells. T. gondii infection of the retinal pigment epithelial cells alters the secretion of growth factors and induces proliferation of adjacent uninfected epithelial cells. This increases susceptibility of the cells to parasite infection, and may be the basis of the characteristic hyperpigmented toxoplasmic retinal lesion. Infected epithelial cells also generate a vigorous immunologic response, and influence the activity of leukocytes that infiltrate the retina. A range of T. gondii genotypes are associated with human ocular toxoplasmosis, and individual immunogenetics -including polymorphisms in genes encoding innate immune receptors, human leukocyte antigens and cytokines- impacts the clinical manifestations. Research into basic pathogenic mechanisms of ocular toxoplasmosis highlights the importance of prevention and suggests new biological drug targets for established disease.

Sero-molecular detection, multi-locus genotyping, and clinical manifestations of ocular toxoplasmosis in patients in northwest Iran

BACKGROUND

Our goal was to use molecular techniques to verify and characterise clinical diagnoses of ocular toxoplasmosis. Clinical cases were evaluated against IgM and IgG Toxoplasma antibodies, and IgG avidity was tested. B1 gene was assessed for molecular detection, and multi-locus genotyping were conducted to type Toxoplasma infections.

METHODS

A cross-sectional study was conducted in 33 patients with suspected active ocular toxoplasmosis. Patients were examined by an ophthalmologist and clinical manifestations were recorded. Toxoplasma gondii IgG and IgM from serum samples were analysed by chemiluminescence immunoassay and ELISA. Acute vs chronic infection was evaluated by IgG avidity testing. Molecular diagnosis of T. gondii infection targeted the B1 gene, and the T. gondii genotype was determined by amplification of the GRA6, SAG2, SAG3, BTUB and APICO loci. The correlation of age, gender, occupation, education, contact with cats or soil, and the consumption of undercooked meat with the incidence of ocular toxoplasmosis was evaluated.

RESULTS

Twenty-eight patients (84.8%) were seropositive, two (6%) were both IgG and IgM positive, while one (3%) showed IgG avidity <40%. Molecular testing confirmed toxoplasmosis in 27 patients (81.8%). Chorioretinal scarring (p=0.014) and posterior uveitis (p=0.004) was significantly associated with ocular toxoplasmosis patients. Multi-locus genotyping showed genotype I. Ocular toxoplasmosis showed no significant correlation with gender, age, behaviours, occupation or education.

CONCLUSION

Clinical manifestations, serological and molecular detection of Toxoplasma were highly correlated in the diagnosis of ocular toxoplasmosis. Genotype I was predominant in ocular toxoplasmosis in northwest Iran. A larger comparative study should be conducted to provide a broader view of the molecular epidemiology of T. gondii genotypes and its role in toxoplasmosis.

Effects of Congenital Ocular Toxoplasmosis on Peripheral Retinal Vascular Development in Premature Infants at Low Risk for Retinopathy of Prematurity

Congenital toxoplasmosis and retinopathy of prematurity (ROP) are two devastating clinical entities of the newborn. There is little information in the literature about the interaction between congenital infections and retinal vascular development at the fetal stage, and none regarding the relationship between ROP and congenital toxoplasmosis. In this report, we present two premature newborns diagnosed with congenital toxoplasmosis with ocular involvement, accompanied by ROP with interrupted retinal vascularization, peripheral avascular regions, and retinal detachment. The aim of this paper is to emphasize the possibility of ROP and congenital toxoplasmosis coexistence wherein one condition may mask the other and make it difficult to distinguish the cause of retinal detachment. Timely management with medical and surgical treatment of congenital toxoplasmosis and ROP could save eyes and vision in those cases.

An update on inflammatory choroidal neovascularization: epidemiology, multimodal imaging, and management

Inflammatory choroidal neovascular membranes are challenging to diagnose and manage. A number of uveitic entities may be complicated by the development of choroidal neovascularization leading to a decrease in central visual acuity. In conditions such as punctate inner choroidopathy, development of choroidal neovascularization is extremely common and must be suspected in all cases. On the other hand, in patients with conditions such as serpiginous choroiditis, and multifocal choroiditis, it may be difficult to differentiate between inflammatory choroiditis lesions and choroidal neovascularization. Multimodal imaging analysis, including the recently introduced technology of optical coherence tomography angiography, greatly aid in the diagnosis and management of inflammatory choroidal neovascularization. Management of these neovascular membranes consists of anti-vascular growth factor agents, with or without concomitant anti-inflammatory and/or corticosteroid therapy.

CCR5 chemokine receptor gene polymorphisms in ocular toxoplasmosis

CC chemokine receptor type 5 (CCR5) is a chemokine receptor that influences the immune response to infectious and parasitic diseases. This study aimed to determine whether the CCR5Δ32 and CCR5 59029 A/G polymorphisms are associated with the development of ocular toxoplasmosis in humans. Patients with positive serology for Toxoplasma gondii were analyzed and grouped as 'with ocular toxoplasmosis' (G1: n=160) or 'without ocular toxoplasmosis' (G2: n=160). A control group (G3) consisted of 160 individuals with negative serology. The characterization of the CCR5Δ32 and CCR5 59029 A/G polymorphisms was by PCR and by PCR-RFLP, respectively. The difference between the groups with respect to the mean age (G1: mean age: 47.3, SD±19.3, median: 46 [range: 18-95]; G2: mean age: 61.3, SD±13.7, median: 61 [range: 21-87]; G3: mean age: 38.8, SD±17.9, median: 34 [range: 18-80]) was statistically significant (G1 vs.G2: p-value <0.0001; t=7.21; DF=318; G1 vs.G3: p-value <0.0001; t=4.32; DF=318; G2 vs. G3: p-value <0.0001; t=9.62; DF=318). The Nagelkerke r² value was 0.040. There were statistically significant differences for the CCR5/CCR5 (p-value=0.008; OR=0.261), AA (p-value=0.007; OR=2.974) and AG genotypes (p-value=0.018; OR=2.447) between G1 and G2. Individuals with the CCR5/CCR5 genotype and simultaneously the CCR5-59029 AA or AG genotypes have a greater risk of developing ocular toxoplasmosis (4% greater), which may be associated with a strong and persistent inflammatory response in ocular tissue.

Evidence of increased exposure to Toxoplasma gondii in individuals with recent onset psychosis but not with established schizophrenia

A possible role for Toxoplasma gondii in the etiopathogenesis of schizophrenia is supported by epidemiological studies and animal models of infection. However, recent studies attempting to link Toxoplasma to schizophrenia have yielded mixed results. We performed a nested case-control study measured serological evidence of exposure to Toxoplasma gondii in a cohort of 2052 individuals. Within this cohort, a total of 1481 individuals had a psychiatric disorder and 571 of were controls without a psychiatric disorder. We found an increased odds of Toxoplasma exposure in individuals with a recent onset of psychosis (OR 2.44, 95% Confidence Interval 1.4–4.4, p < .003). On the other hand, an increased odds of Toxoplasma exposure was not found in individuals with schizophrenia or other psychiatric disorder who did not have a recent onset of psychosis. By identifying the timing of evaluation as a variable, these findings resolve discrepancies in previous studies and suggest a temporal relationship between Toxoplasma exposure and disease onset.

The protozoan parasite Toxoplasma gondii has been previously associated with an increased risk of serious psychiatric disorders such as schizophrenia. However, this association has been found in some studies and not others. We examined whether the differences among previous studies might be explained by the timing of patient evaluation and testing. We found that individuals who were evaluated soon after the onset of psychosis had increased odds of exposure to Toxoplasma gondii as evidenced by the measurement of antibodies in their blood. However. we did not find an increased rate of exposure to Toxoplasma gondii in individuals who had a diagnosis of schizophrenia or bipolar disorder but who did not have recent onset psychosis. Our findings are consistent with Toxoplasma exposure occurring around the time of onset of psychiatric symptoms in individuals with schizophrenia. Our findings might lead to the evaluation of new methods for the early treatment of schizophrenia in some individuals.

Ocular Autoimmune Systemic Inflammatory Infectious Study - Report 3: Posterior and Panuveitis

PURPOSE

To report the pattern of posterior and panuveitis at a tertiary referral center in Singapore.

METHODS

Subgroup retrospective analysis of 334 new posterior and panuveitis cases, from the Ocular Autoimmune Systemic Inflammatory Infectious Study (OASIS) database. Descriptive analysis was performed and visual outcome and complications were reported.

RESULTS

The etiology for posterior uveitis and panuveitis was infectious in 162 patients (48.5%), non-infectious in 144 patients (43.1%), and idiopathic in 28 patients (8.4%). More patients with bilateral disease had a non-infectious etiology (n = 82, 50.9%) (p = 0.012). The most common complication was epiretinal membrane (n = 20, 12.3%) for the infectious group and cystoid macular edema (n = 12, 8.3%) for the non-infectious group.

CONCLUSIONS

The proportion of etiologies in our cohort varies from other studies. Understanding the variations and demographic associations allows the diagnosis and management of posterior and panuveitis to be further improved.

Vaccination with recombinant adenovirus expressing multi-stage antigens of Toxoplasma gondii by the mucosal route induces higher systemic cellular and local mucosal immune responses than with other vaccination routes

Toxoplasmosis caused by Toxoplasma gondii, an obligate intracellular protozoan, is a cause of congenital disease and abortion in humans and animals. Various vaccination strategies against toxoplasmosis in rodent models have been used in the past few decades; however, effective vaccines remain a challenge. A recombinant adenovirus vaccine expressing ubiquitin-conjugated multi-stage antigen segments (Ad-UMAS) derived from different life-cycle stages of T. gondii was constructed previously. Here, we compared the immune responses and protection effects in vaccination of mice with Ad-UMAS by five vaccination routes including intramuscular (i.m.), intravenous (i.v.), subcutaneous (s.c.), intraoral (i.o.), and intranasal (i.n.). Much higher levels of T. gondii-specific IgG and IgA antibodies were detected in the sera of the intraoral and intranasal vaccination groups on day 49 compared with controls (p < 0.05). The percentages of CD8⁺ T-cells in mice immunized intranasally and intraorally were larger than in mice immunized intramuscularly (p < 0.05). The highest level of IL-2 and IFN-γ was detected in the group with nasal immunization, and splenocyte proliferation activity was significantly enhanced in mice immunized via the oral and nasal routes. Furthermore, the higher survival rate (50%) and lower cyst numbers observed in the intraoral and intranasal groups all indicate that Ad-UMAS is far more effective in protecting mice against T. gondii infection via the mucosal route. Ad-UMAS could be an effective and safe mucosal candidate vaccine to protect animals and humans against T. gondii infection.

[Effect of antenatal spiramycin treatment on the frequency of retinochoroiditis due to congenital toxoplasmosis in a Colombian cohort]

INTRODUCTION

Gestational toxoplasmosis is frequent and severe. There is still debate about the benefits of treatment against ocular manifestations in the newborn. Spiramycin treatment is used for this purpose, unfortunately prenatal diagnosis is sometimes delayed and pregnant women are not treated.

OBJECTIVE

To describe the relationship between treatment with spiramycin during pregnancy in mothers with gestational toxoplasmosis and development of ocular toxoplasmosis in newborns.

MATERIALS AND METHODS

We conducted a descriptive study of a case series. We evaluated a prospective cohort of patients diagnosed with gestational toxoplasmosis during three years at the Retinology Service at the Clínica Universitaria Bolivariana in Medellín.

RESULTS

Gestational toxoplasmosis was found in 23 mothers; 15 (65%) were treated during pregnancy with 3 g per day of spiramycin, eight (35%) patients were untreated. In the treated group just one newborn developed ocular toxoplasmosis (6.6%), in contrast with five (62.5%) of the eight patients who did not receive treatment. These results suggest that pregnancy treatment reduces the relative risk of ocular toxoplasmosis in the newborn by 96% (95% CI: 33 - 100%). Only two (14%) of the patients who were evaluated, had nervous system involvement related to toxoplasmosis in CT scan or cerebral ultrasound. These two patients also developed ocular pathology and were diagnosed at the time of birth, so they did not received antenatal treatment.

CONCLUSIONS

A protective effect was found against the ocular involvement in patients whose mother received treatment with spiramycin (OR=0.04;95% CI: 0.00-0.67), p<0.01 (Fisher's Exact Test).

DNA Microarray Detection of 18 Important Human Blood Protozoan Species

Background

Accurate detection of blood protozoa from clinical samples is important for diagnosis, treatment and control of related diseases. In this preliminary study, a novel DNA microarray system was assessed for the detection of Plasmodium, Leishmania, Trypanosoma, Toxoplasma gondii and Babesia in humans, animals, and vectors, in comparison with microscopy and PCR data. Developing a rapid, simple, and convenient detection method for protozoan detection is an urgent need.

Methodology/Principal Findings

The microarray assay simultaneously identified 18 species of common blood protozoa based on the differences in respective target genes. A total of 20 specific primer pairs and 107 microarray probes were selected according to conserved regions which were designed to identify 18 species in 5 blood protozoan genera. The positive detection rate of the microarray assay was 91.78% (402/438). Sensitivity and specificity for blood protozoan detection ranged from 82.4% (95%CI: 65.9% ~ 98.8%) to 100.0% and 95.1% (95%CI: 93.2% ~ 97.0%) to 100.0%, respectively. Positive predictive value (PPV) and negative predictive value (NPV) ranged from 20.0% (95%CI: 2.5% ~ 37.5%) to 100.0% and 96.8% (95%CI: 95.0% ~ 98.6%) to 100.0%, respectively. Youden index varied from 0.82 to 0.98. The detection limit of the DNA microarrays ranged from 200 to 500 copies/reaction, similar to PCR findings. The concordance rate between microarray data and DNA sequencing results was 100%.

Conclusions/Significance

Overall, the newly developed microarray platform provides a convenient, highly accurate, and reliable clinical assay for the determination of blood protozoan species.

More than 1 billion people are infected with blood protozoan diseases worldwide. The most common blood protozoa in humans, animals, and vectors include Plasmodium, Leishmania, Trypanosoma, Toxoplasma gondii and Babesia. Due to similar morphology among different blood protozoan species, misdiagnosis always occurs. Most molecular techniques are only carried out in laboratories, with a small number of samples detected simultaneously. Meanwhile, common detection methods may not be convenient for field investigation of large amounts of samples. In order to better manage blood protozoan infection, proper tools are required for the monitoring of these pathogens. Here, a comprehensive and sensitive DNA microarray was developed and tested, which allowed the parallel detection of 18 blood protozoan species.

Host and Toxoplasma gondii genetic and non-genetic factors influencing the development of ocular toxoplasmosis: A systematic review

Toxoplasmosis is a cosmopolitan infection caused by the apicomplexan parasite Toxoplasma gondii. This infectious disease is widely distributed across the world where cats play an important role in its spread. The symptomatology caused by this parasite is diverse but the ocular affectation emerges as the most important clinical phenotype. Therefore, we conducted a systematic review of the current knowledge of ocular toxoplasmosis from the genetic diversity of the pathogen towards the treatment available for this infection. This review represents an update to the scientific community regarding the genetic diversity of the parasite, the genetic factors of the host, the molecular pathogenesis and its association with disease, the available diagnostic tools and the available treatment of patients undergoing ocular toxoplamosis. This review will be an update for the scientific community in order to encourage researchers to deploy cutting-edge investigation across this field.

Relevance of and New Developments in Serology for Toxoplasmosis

Toxoplasmosis is a widespread parasitic disease caused by the intracellular parasite Toxoplasma gondii with a wide spectrum of clinical outcomes. The biological diagnosis of toxoplasmosis is often difficult and of paramount importance because clinical features are not sufficient to discriminate between toxoplasmosis and other illnesses. Serological tests are the most widely used biological tools for the diagnosis of toxoplasmosis worldwide. This review focuses on the crucial role of serology in providing answers to the most important questions related to the epidemiology and diagnosis of toxoplasmosis in human pathology. Notwithstanding their undeniable importance, serological tools need to be continuously improved and the interpretation of the ensuing results remains complex in many circumstances.

Uveitis

Multidisciplinary management in the diagnosis and management of patients with ocular inflammatory disease is often critical. The workup of uveitis or scleritis may reveal an underlying systemic disease. Recognition of inflammation by the primary care physician can facilitate prompt referral to a uveitis specialist and improve patient outcomes. The primary care physician can assist the ophthalmologist in monitoring for potential side effects of corticosteroids and immunosuppressive drugs, including the newer biologic agents. The ophthalmologist in turn can assist the primary care physician in recognizing that active uveitis may suggest incomplete control of preexisting conditions.