Multiple cases of acquired toxoplasmosis retinitis presenting in an outbreak

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.

Exploring the association between precipitation and population cases of ocular toxoplasmosis in Colombia

BACKGROUND

Previous studies suggest a relationship between precipitation and ocular toxoplasmosis (OT) reactivation and congenital toxoplasmosis infection. We aimed to investigate the relationship between precipitation and the frequency of new OT cases in Colombia from 2015 to 2019.

METHODOLOGY

This retrospective cohort study analyzed data obtained from a claims-based database created by the Colombian Ministry of Health and national registries of precipitation of the Institute of Hydrology, Meteorology, and Environmental Studies. We estimated the daily number of OT cases, interpolating data from the average number of annual cases from 2015 to 2019. Then, we compared exposures (mean daily precipitation) in the case period in which the events (interpolated OT new cases) occurred by a quasi-Poisson regression, combined with a distributed lag non-linear model to estimate the non-linear and lag-response curve.

PRINCIPAL FINDINGS

In the 5-year analysis, there were 1,741 new OT cases. Most of the cases occurred in 2019, followed by 2015 and 2018. New OT cases among departments were significantly different (P< 0.01). The cumulative exposure-response curve was decreasing for most departments. Nevertheless, in Chocó, Bogotá, Cesar, Cauca, and Guajira, when a certain amount of precipitation accumulates, the relative risk (RR) increases, which was contrary to the pattern observed in the other regions. The response curves to the one-day lag showed that precipitation influences the RR; however, the trends vary by department. Finally, an increasing trend in the number of cases was directly proportional to precipitation in Guajira, Atlántico, Norte de Santander, Santander, Caquetá and Quindío (r = 0.84; P< 0.05).

CONCLUSIONS

Precipitation influenced the RR for new OT cases. However, varying trends among geographical regions (departments) lead us to hypothesize that other sociodemographic, behavioral, and environmental variables, such as wind and water contamination, could influence the RR.

Calomys callosus: An Experimental Animal Model Applied to Parasitic Diseases Investigations of Public Health Concern

The appearance and spread of parasitic diseases around the world aroused the interest of the scientific community to discover new animal models for improving the quality and specificity of surveys. Calomys callosus is a rodent native to South America, an easy handling model, with satisfactory longevity and reproducibility. C. callosus is susceptible to toxoplasmosis and can be used as experimental model for the study the pathogenesis, treatment, vertical transmission, and ocular toxoplasmosis. C. callosus can also be used to study cutaneous and visceral leishmaniasis, as the animals present cutaneous lesions, as well as parasites in the organs. C. callosus has epidemiological importance in Chagas disease, and since it is a Trypanosoma cruzi natural host in which rodents show high parasitemia and lethality, they are also effective as a model of congenital transmission. In the study of schistosomiasis, Schistosoma mansoni was proven to be a C. callosus natural host; thus, this rodent is a great model for fibrosis, hepatic granulomatous reaction, and celloma associated with lymphomyeloid tissue (CALT) during S. mansoni infection. In this review, we summarize the leading studies of parasitic diseases that used C. callosus as a rodent experimental model, describing the main uses and characteristics that led them to be considered an effective model.

Ocular toxoplasmosis, an overview focusing on clinical aspects

Toxoplasma gondii is a widespread protozoan parasite infecting approximately one third of the world population. After proliferation of tachyzoites during the acute stage, the parasite forms tissue cysts in various anatomical sites and establishes chronic infection. Nowadays the nature of the interplay between the protozoan and its human host remains elusive. This is clearly evident in ocular toxoplasmosis, in which the parasite establishes an ambivalent relationship with the eye, manipulating the immune response and inducing variable initial lesions and further relapses. This review will focus on epidemiology and environmental, parasite and host related risk factors, clinical manifestations and laboratory findings, treatment and prophylaxis approaches in ocular toxoplasmosis. An image collection of patients referred to the Unit of Ophthalmology of Pisa's Hospital will be presented, too.

Outbreaks of clinical toxoplasmosis in humans: five decades of personal experience, perspectives and lessons learned

Background

The protozoan parasite Toxoplasma gondii has a worldwide distribution and a very wide host range, infecting most warm-blooded hosts. Approximately 30% of humanity is infected with T. gondii, but clinical toxoplasmosis is relatively infrequent. Toxoplasmosis has a wide range of clinical symptoms involving almost all organ systems. In most persons that acquire infection postnatally, symptoms (when present) are mild and mimic other diseases such as flu, Lyme disease, Q fever, hematological alterations, or mumps. It is likely that clinical disease is more common than reported. The ingestion of infected meat or food and water contaminated with oocysts are the two main modes of postnatal transmission of Toxoplasma gondii. The infective dose and the incubation period of T. gondii infection are unknown because there are no human volunteer experiments.

Methods

Here, I have critically reviewed outbreaks of clinical toxoplasmosis in humans for the past 55 years, 1966–2020. Information from oocyst-acquired versus meat-acquired infections was assessed separately.

Results

Most outbreaks were from Brazil. There were no apparent differences in types or severity of symptoms in meat- versus oocyst-acquired infections. Fever, cervical lymphadenopathy, myalgia, and fatigue were the most important symptoms, and these symptoms were not age-dependent. The incubation period was 7–30 days. A genetic predisposition to cause eye disease is suspected in the parasites responsible for three outbreaks (in Brazil, Canada, and India). Only a few T. gondii tissue cysts might suffice to cause infection, as indicated by outbreaks affecting some (but not all) individuals sharing a meal of infected meat.

Conclusions

Whether the high frequency of outbreaks of toxoplasmosis in humans in Brazil is related to environmental contamination, poor hygiene, socioeconomic conditions, or to genotypes of T. gondii needs investigation.

Graphic Abstract

Autoantibodies Against Ubiquitous and Confined Antigens in Patients With Ocular, Neuro-Ophthalmic and Congenital Cerebral Toxoplasmosis

Toxoplasma gondii infection can trigger autoreactivity by different mechanisms. In the case of ocular toxoplasmosis, disruption of the blood-retinal barrier may cause exposure of confined retinal antigens such as recoverin. Besides, cross-reactivity can be induced by molecular mimicry of parasite antigens like HSP70, which shares 76% identity with the human ortholog. Autoreactivity can be a determining factor of clinical manifestations in the eye and in the central nervous system. We performed a prospective observational study to determine the presence of autoantibodies against recoverin and HSP70 by indirect ELISA in the serum of 65 patients with ocular, neuro-ophthalmic and congenital cerebral toxoplasmosis. We found systemic autoantibodies against recoverin and HSP70 in 33.8% and 15.6% of individuals, respectively. The presence of autoantibodies in cases of OT may be related to the severity of clinical manifestations, while in cases with CNS involvement they may have a protective role. Unexpectedly, anti-recoverin antibodies were found in patients with cerebral involvement, without ocular toxoplasmosis; therefore, we analyzed and proved cross-reactivity between recoverin and a brain antigen, hippocalcin, so the immunological phenomenon occurring in one immune-privileged organ (e.g. the central nervous system) could affect the environment of another (egg. the eye).

Bilateral ocular toxoplasmosis in a returning traveller: age and route of infection as potential risk factors

We report the case of a 69-year-old man, who presented in the UK with a short history of deteriorating vision and clinical features of bilateral atypical retinochoroiditis, after travelling to South America. Vitreous samples demonstrated Toxoplasma gondii DNA by PCR. Serology tests demonstrated recent acquired Toxoplasma gondii infection with IgM antibodies. He responded well to treatment with trimethoprim-sulfamethoxazole, azithromycin and oral steroids. This case is a reminder of the global importance of Toxoplasma related eye disease, and its uncommon bilateral severe presentation in a returning traveller, where the risk factors were age and the route of infection likely to be a virulent parasite oocyst from vegetables or water rather than undercooked meat or direct contact with cats.

Clinical and Multimodal Imaging Findings and Risk Factors for Ocular Involvement in a Presumed Waterborne Toxoplasmosis Outbreak, Brazil1

After a 2015 outbreak, 23% of patients had retinochoroiditis, indicating that patients with acquired toxoplasmosis should have long-term follow-up, regardless of initial ocular involvement.

In 2015, an outbreak of presumed waterborne toxoplasmosis occurred in Gouveia, Brazil. We conducted a 3-year prospective study on a cohort of 52 patients from this outbreak, collected clinical and multimodal imaging findings, and determined risk factors for ocular involvement. At baseline examination, 12 (23%) patients had retinochoroiditis; 4 patients had bilateral and 2 had macular lesions. Multimodal imaging revealed 2 distinct retinochoroiditis patterns: necrotizing focal retinochoroiditis and punctate retinochoroiditis. Older age, worse visual acuity, self-reported recent reduction of visual acuity, and presence of floaters were associated with retinochoroiditis. Among patients, persons >40 years of age had 5 times the risk for ocular involvement. Five patients had recurrences during follow-up, a rate of 22% per person-year. Recurrences were associated with binocular involvement. Two patients had late ocular involvement that occurred >34 months after initial diagnosis. Patients with acquired toxoplasmosis should have long-term ophthalmic follow-up, regardless of initial ocular involvement.

Multimodal Imaging in Ocular Toxoplasmosis

Multimodal imaging relies on combination of multiple imaging modalities to precisely delineate pathological changes in the posterior segment of the eye associated with a wide range of conditions. This combined application of fundus photography, optical coherence tomography, fundus reflectance/autofluorescence and fundus angiography (with fluorescein, indocyanine green and/or optical coherence tomography) is of great utility for assessment of patients with ocular toxoplasmosis. Multimodal imaging is helpful to characterize the typical pattern of toxoplasmic retinochoroiditis, with primary focal inflammatory involvement of the neurosensory retina, and secondary changes at the level of underlying choroid, retinal blood vessels, vitreous and even optic disc. It may also be valuable to document and follow local complications, including macular edema, vascular occlusions, and choroidal neovascularization, among others.

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.

Epidemiology of a toxoplasmosis outbreak in a research institution in northern Paraná, Brazil

Toxoplasmosis is a reportable disease in Brazil. The objective of this study was to investigate a toxoplasmosis outbreak at a research institution in Londrina-PR, Brazil. The outbreak was reported in October 2015; however, the first cases occurred in August 2015. Blood samples were collected from 674 persons at the institution. Samples were collected from soil, water (water tank) and food (vegetables) served in the restaurant. Each participant responded to an epidemiological questionnaire. For the blood samples, a chemiluminescent microparticle immunoassay was performed to detect IgM, IgG and specific IgG avidity antibodies; 10.8% (73/674) had evidence of acute toxoplasmosis. Statistical analysis showed a significant association (p < .001) between acute infection and eating lunch in the restaurant of the institution. Regarding the types of food offered in the restaurant during the period, there was a significant association between consuming raw salad (p < .001) and becoming ill. We conclude that the vegetables or raw vegetables served in the restaurant were probably the source of infection; however, the long period between exposure and case reporting made it difficult to identify the source of transmission.

Excretion of Toxoplasma gondii oocysts from Feral Cats in Korea

Sporulated oocysts from the feces of infected cats with Toxoplasma gondii can cause detrimental disease in both humans and animals. To investigate the prevalence of feral cats that excrete T. gondii oocysts in the feces, we examined fecal samples of 563 feral cats over a 3-year period from 2009 to 2011. Oocysts of T. gondii excreted into the feces were found from 4 of 128 cats in 2009 (3.1%) and one of 228 (0.4%) in 2010 while none of the 207 cats in 2010 were found positive with oocysts in their feces, resulting in an overall prevalence rate of 0.89% (5/563) between 2009 and 2011. Among the 5 cats that tested positive with T. gondii oocysts, 4 of the cats were male and 1 was a female with an average body weight of 0.87 kg. Numerous tissue cysts of 60 μm in diameter with thin (<0.5 μm) cyst walls were found in the brain of one of the 5 cats on necropsy 2 months after the identification of oocysts in the feces. A PCR amplification of the T. gondii-like oocysts in the feces of the positive cats using the primer pairs Tox-5/Tox-8 and Hham34F/Hham3R confirmed the presence of T. gondii oocysts in the feces. This study provides a good indication of the risk assessment of feral cats in the transmission of T. gondii to humans in Korea.

Primary Ocular Toxoplasmosis Presenting to Uveitis Services in a Non-endemic Setting

PURPOSE

This study sought to describe the different clinical features and presentations of primary ocular toxoplasmosis in a setting not demonstrating an outbreak of disease.

METHODS

This was a retrospective review of patients presenting to uveitis management services in Auckland and Hamilton, New Zealand between 2003 to 2018 with uveitis and positive toxoplasmosis immunoglobulin M serology.

RESULTS

We identified 16 patients with primary acquired toxoplasmosis infection and ocular involvement. The mean age was 53 years. Systemic symptoms were reported in 56% (9 / 16). Visual acuity was reduced to 20 / 30 or less in 50% of patients (8 / 16). A single focus of retinitis without a pigmented scar was the salient clinical feature in 69% (11 / 16). Optic nerve inflammation was the sole clinical finding in 19% (3 / 16). Bilateral arterial vasculitis was the sole clinical finding in 13% (2 / 16). A delay in the diagnosis of toxoplasmosis of more than two weeks occurred in 38% (6 / 16) due to an initial alternative diagnosis. Antibiotic therapy was prescribed in all cases. Vision was maintained or improved in 69% (11 / 16) at the most recent follow-up visit (15 months to 10 years). Relapse occurred in 69% (11 / 16), typically within four years from the initial presentation.

CONCLUSIONS

Primary ocular toxoplasmosis presenting in adulthood is a relatively uncommon cause of posterior uveitis in New Zealand. This condition should be considered in any patient presenting with retinitis or optic nerve inflammation without a retinochoroidal scar. This disease tends to relapse; thus, close follow-up is required.

Ocular Toxoplasmosis Presenting as Subretinal Macrocyst

Purpose:

To report a case of unilateral retinal detachment with a large subretinal macrocyst, representing an atypical presentation of ocular toxoplasmosis.

Case Report:

A healthy 30-year-old woman presented with a two month history of progressive visual loss in her right eye. Funduscopy revealed vitreous condensations, total retinal detachment with a large subretinal orange-red cystic mass and multiple retinal breaks sealed with surrounding retinal scars. B-scan echography showed a large subretinal cyst with non-homogenous tissue echogenicity. Pars plana deep vitrectomy and complete cyst removal were performed. Histopathologic examination of the excised cyst revealed intraretinal toxoplasma cysts containing bradyzoites. Analysis of intraocular fluids by polymerase chain reaction (PCR) and serologic tests also supported the diagnosis. After six months, the retina was completely attached with no signs of inflammation.

Conclusion:

Toxoplasma retinochoroiditis should be considered in the differential diagnoses of retinal detachment with subretinal cyst.

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 as a Parasite in Food: Analysis and Control

Foodborne infections are a significant cause of morbidity and mortality worldwide, and foodborne parasitic diseases, though not as widespread as bacterial and viral infections, are common on all continents and in most ecosystems, including arctic, temperate, and tropical regions. Outbreaks of disease resulting from foodstuffs contaminated by parasitic protozoa have become increasingly recognized as a problem in the United States and globally. Increased international trade in food products has made movement of these organisms across national boundaries more frequent, and the risks associated with infections have become apparent in nations with well-developed food safety apparatus in place.

Isolation and characterization of Toxoplasma gondii from small ruminants (sheep and goats) in Chennai City, South India

The present study aimed for the isolation and genotyping of Toxoplasma gondii from small ruminants (sheep and goats). 14 out of 193 tissue samples (either brain and heart) tested positive by MDAT for anti-T. gondii antibodies, were selected and bioassayed, which resulted 4 samples positive for T. gondii after 40 days of post inoculation. Four samples consisting of 3 numbers of sheep and 1 number of goat tissues out of 14 samples detected by B1 PCR, were genotyped at SAG3 locus by nested polymerase chain reaction-restriction fragment length polymorphism technique (nPCR-RFLP). The results of the present study revealed that the four isolates designated as TgShIn19, TgShIn76, TgShIn77 and TgGtIn27 were circulating in small ruminants, were belonged to genotypes of type II (TgShIn19) and type III (TgShIn76, TgShIn77 and TgGtIn27) which are in concordance with the previously reported genotypes from other animal species and further this presumptive results indicating that the genotype II and III could be the predominant in different animal species including birds and humans in India.

Decline in Ocular Toxoplasmosis over 40 Years at a Tertiary Referral Practice in the United States

PURPOSE

To identify whether there has been a decline in ocular toxoplasmosis at a tertiary uveitis practice.

METHODS

Retrospective review of new patients at the University of Illinois Uveitis Service from 1973 to 2012.

RESULTS

There were 6820 patients with adequate records for inclusion; 323 (4.7%) were diagnosed with ocular toxoplasmosis. There was a 78.0% decline in prevalence of ocular toxoplasmosis from 2008 to 2012 compared with 1973 to 1977. Compared with the aggregate uveitis population, toxoplasmosis patients were more likely to be Hispanic (p<0.0001) and less likely to be African American (p<0.0001). Ocular toxoplasmosis in Hispanics commonly occurred in foreign-born patients (85.3%).

CONCLUSIONS

The diagnosis of ocular toxoplasmosis at our clinic declined, with Hispanics accounting for an increasing proportion of cases. These trends are consistent with the decreasing toxoplasmosis seropositivity in the United States, but may also reflect decreased referrals due to improved management of ocular toxoplasmosis in primary clinics.

Toxoplasma gondii-A Gastrointestinal Pathogen Associated with Human Brain Diseases

Serious psychiatric disorders such as schizophrenia, bipolar disorder, and major depression are important causes of mortality and morbidity worldwide. While these are primarily diseases involving altered brain functioning, numerous studies have documented increased rates of gastrointestinal inflammation and dysfunction in many individuals with these disorders. Toxoplasma gondii is an apicomplexan protozoan intracellular parasite with a widespread distribution in both developed and developing countries. Toxoplasma organisms enter the ecosystem through the shedding of oocysts by Toxoplasma-infected felines. In almost all cases of postnatal human infection, Toxoplasma enters its hosts through the intestinal tract either by the ingestion of oocysts or by the consumption of meat from food animals which themselves were infected by Toxoplasma oocysts. It had previously been thought that most cases of Toxoplasma infection in immune competent children and adults were inapparent and asymptomatic. However, recent studies cast doubt on this concept as exposure to Toxoplasma has been associated with a range of acute and chronic symptoms. Of particular note has been the finding of an increased rate of a range of neurological and psychiatric disorders associated with serological evidence of Toxoplasma exposure. A role of Toxoplasma infection in brain diseases is also supported by the consistent finding of altered cognition and behavior in animal models of infections. Much of the attention relating to the role of Toxoplasma infection in neuropsychiatric disorders has focused on the brain, where Toxoplasma tissue cysts can persist for extended periods of time. However, recent discoveries relating to the role of the gastrointestinal tract in cognition and behavior suggest that Toxoplasma may also increase susceptibility to human brain diseases through immune activation, particularly involving the gastrointestinal mucosa. The study of the pathways relating to the pathobiology and immunology of Toxoplasma infection may provide insights into the pathogenesis of a range of human neuropsychiatric disorders as well as into cognitive functioning in otherwise healthy individuals.

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.

Experimental Toxoplasmosis in Rats Induced Orally with Eleven Strains of Toxoplasma gondii of Seven Genotypes: Tissue Tropism, Tissue Cyst Size, Neural Lesions, Tissue Cyst Rupture without Reactivation, and Ocular Lesions

BACKGROUND

The protozoan parasite Toxoplasma gondii is one of the most widely distributed and successful parasites. Toxoplasma gondii alters rodent behavior such that infected rodents reverse their fear of cat odor, and indeed are attracted rather than repelled by feline urine. The location of the parasite encysted in the brain may influence this behavior. However, most studies are based on the highly susceptible rodent, the mouse.

METHODOLOGY/PRINCIPAL FINDINGS

Latent toxoplasmosis was induced in rats (10 rats per T. gondii strains) of the same age, strain, and sex, after oral inoculation with oocysts (natural route and natural stage of infection) of 11 T. gondii strains of seven genotypes. Rats were euthanized at two months post inoculation (p.i.) to investigate whether the parasite genotype affects the distribution, location, tissue cyst size, or lesions. Tissue cysts were enumerated in different regions of the brains, both in histological sections as well in saline homogenates. Tissue cysts were found in all regions of the brain. The tissue cyst density in different brain regions varied extensively between rats with many regions highly infected in some animals. Overall, the colliculus was most highly infected although there was a large amount of variability. The cerebral cortex, thalamus, and cerebellum had higher tissue cyst densities and two strains exhibited tropism for the colliculus and olfactory bulb. Histologically, lesions were confined to the brain and eyes. Tissue cyst rupture was frequent with no clear evidence for reactivation of tachyzoites. Ocular lesions were found in 23 (25%) of 92 rat eyes at two months p.i. The predominant lesion was focal inflammation in the retina. Tissue cysts were seen in the sclera of one and in the optic nerve of two rats. The choroid was not affected. Only tissue cysts, not active tachyzoite infections, were detected. Tissue cysts were seen in histological sections of tongue of 20 rats but not in myocardium and leg muscle.

CONCLUSION/SIGNIFICANCE

This study reevaluated in depth the rat model of toxoplasmosis visualizing cyst rupture and clarified many aspects of the biology of the parasite useful for future investigations.

Antibiotics versus no treatment for toxoplasma retinochoroiditis

BACKGROUND

Acute toxoplasma retinochoroiditis causes transient symptoms of ocular discomfort and may lead to permanent visual loss. Antibiotic treatment aims primarily to reduce the risk of permanent visual loss, recurrent retinochoroiditis, and the severity and duration of acute symptoms. There is uncertainty about the effectiveness of antibiotic treatment.

OBJECTIVES

To compare the effects of antibiotic treatment versus placebo or no treatment for toxoplasma retinochoroiditis.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision group Trials Register) (2016, Issue 1), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to February 2016), EMBASE (January 1980 to February 2016), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to February 2016), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 22 February 2016. We searched the reference lists of identified articles and contacted pharmaceutical companies for unpublished trials.

SELECTION CRITERIA

We included randomised controlled trials that compared any antibiotic treatment against placebo or no treatment. We excluded trials that included immunocompromised participants. We considered any antibiotic treatment known to be active against Toxoplasma gondii. Antibiotic treatment could be given in any dose orally, by intramuscular injection, by intravenous infusion, or by intravitreal injection.

DATA COLLECTION AND ANALYSIS

The primary outcomes for this review were visual acuity at least three months after treatment and risk of recurrent retinochoroiditis. Secondary outcomes were improvement in symptoms and signs of intraocular inflammation, size of lesion, and adverse events. We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

Four trials that randomised a total of 268 participants met the inclusion criteria. In all four studies antibiotic was administered orally.One study conducted in Brazil in both adults and children compared trimethoprim-sulfamexacocol over 20 months to no treatment and was judged to be at high risk of performance, detection, and attrition bias. The other three studies compared antibiotic treatment to placebo. We judged these three studies to be at a mixture of low or unclear risk of bias due to poor reporting. One study conducted in the US in adults studied pyrimethamine-trisulfapyrimidine for eight weeks; one study conducted in the UK in children and adults evaluated pyrimethamine for four weeks; and one study conducted in Brazil in adults investigated trimethoprim-sulfamethoxazole for 12 months. In the last study, all participants had active retinochoroiditis and were treated with antibiotics for 45 days prior to randomisation to trimethoprim-sulfamethoxazole versus placebo.Only the study in Brazil of trimethoprim-sulfamethoxazole over 12 months, in participants with healed lesions, reported the effect of treatment on visual acuity. People treated with antibiotics may have a similar change in visual acuity compared with people treated with placebo at one year (mean difference -1.00 letters, 95% confidence interval (CI) -7.93 to 5.93 letters; 93 participants; low-quality evidence).Treatment with antibiotics probably reduces the risk of recurrent retinochoroiditis compared with placebo (risk ratio (RR) 0.26, 95% CI 0.11 to 0.63; 227 participants; 3 studies; I(2) = 0%; moderate-quality evidence); similar results were seen for acute and chronic retinochoroiditis.The UK study of pyrimethamine for four weeks reported an improvement in intraocular inflammation in treated compared with control participants (RR 1.76, 95% CI 0.98 to 3.19; 29 participants; low-quality evidence). The study in Brazil of trimethoprim-sulfamethoxazole for 12 months stated that the severity of inflammation was higher in the comparator group when compared to the antibiotic-treated group but did not provide further details. In the US study of pyrimethamine-trisulfapyrimidine for eight weeks intraocular inflammation had almost completely resolved by eight weeks in all participants, however in this study all participants received steroid treatment.Two studies (UK and US studies) reported an increased risk of adverse events in treated participants. These were a fall in haemoglobin, leucocyte, and platelet count, nausea, loss of appetite, rash, and arthralgia.

AUTHORS' CONCLUSIONS

Treatment with antibiotics probably reduces the risk of recurrent toxoplasma retinochoroiditis, but there is currently no good evidence that this leads to better visual outcomes. However, absence of evidence of effect is not the same as evidence of no effect. Further trials of people with acute and chronic toxoplasma retinochoroiditis affecting any part of the retina are required to determine the effects of antibiotic treatment on visual outcomes.

Toxoplasmic Retinochoroiditis: Clinical Characteristics and Visual Outcome in a Prospective Study

Purpose

To ascertain the clinical features and visual outcome of toxoplasma retinochoroiditis in a large series of cases.

Subjects and Methods

Two hundred and thirty subjects diagnosed with active toxoplasma retinochoroiditis were prospectively followed for periods ranging from 269 to 1976 days. All patients presented with active retinochoroiditis and positive IgG T. gondii serology at the beginning of the study and received a standardized drug treatment for toxoplasmosis, both in the first episode and in the subsequent recurrences.

Results

The group involved 118 (51.3%) men and 112 (48.7%) women, with ages ranging from 14 to 77 years, mean of 32.4 years (SD = 11.38). Primary retinochoroidal lesions were observed in 52 (22.6%) cases and active retinochoroiditis combined with old scars in 178 (77.4%) subjects at the beginning of the study. A hundred sixty-two recurrent episodes in 104 (45.2%) patients were observed during follow-up. New subclinical retinochoroidal lesions were detected in 23 of 162 (14.2%) recurrences episodes during the follow-up. Posterior segment complications were observed in 73 (31.7%) subjects. Retinochoroidal lesions adjacent to the optic nerve and in the macular area were observed in 27 of 40 (67.5%) cases of severe visual impairment (VA = 20/200 or worse).

Conclusion

Toxoplasma retinochoroiditis in this population had a high recurrence rate after an active episode. Severe visual impairment was associated with location of the retinochoroidal scar, recurrences and posterior segment complications. It is crucial to consider the location of the lesion in studies analyzing visual prognosis as a measure for treatment effectiveness and prevention strategies.

Ocular toxoplasmosis affects millions of people worldwide and is a cause of severe vision loss. Prospective studies on the disease are rare and require long and expensive follow-ups. A network of intricate host and parasite factors can influence its evolution and its treatment is still subject of discussion and controversy. This article describes clinical features in a series of cases prospectively followed, confirming findings of previous studies conducted in other continents, despite the probable genetic variability of the evaluated populations and parasite. In addition, brings insights into the course of the disease and causes of visual impairment that may help future studies on strategies for treatment and prevention.

Toxoplasmosis and Toxocariasis: An Assessment of Human Immunodeficiency Virus Comorbidity and Health-Care Costs in Canada

Toxoplasma gondii and Toxocara spp. are zoonotic parasites with potentially severe long-term consequences for those infected. We estimated incidence and investigated distribution, risk factors, and costs associated with these parasites by examining hospital discharge abstracts submitted to the Canadian Institute for Health Information (2002-2011). Annual incidence of serious toxoplasmosis and toxocariasis was 0.257 (95% confidence interval [CI]: 0.254-0.260) and 0.010 (95% CI: 0.007-0.014) cases per 100,000 persons, respectively. Median annual health-care costs per serious case of congenital, adult-acquired, and human immunodeficiency virus (HIV)-associated toxoplasmosis were $1,971, $763, and $5,744, respectively, with an overall cost of C$1,686,860 annually (2015 Canadian dollars). However, the total economic burden of toxoplasmosis is likely much higher than these direct health-care cost estimates. HIV was reported as a comorbidity in 40% of toxoplasmosis cases and accounted for over half of direct health-care costs associated with clinical toxoplasmosis. A One Health approach, integrating physician and veterinary input, is recommended for increasing public awareness and decreasing the economic burden of these preventable zoonoses.

Epidemiology of Ocular Toxoplasmosis in Three Community Surveys in the Central Region of Ghana, West Africa

PURPOSE

To conduct the first ever population-based survey on ocular toxoplasmosis in the Central Region of Ghana.

METHODS

A cross-sectional population-based study was conducted in three randomly selected communities in the Central Region, Ghana. Visual acuity (VA) measurement, dilated fundus examination by indirect ophthalmoscopy and serology testing were performed on all participants. Ocular toxoplasmosis was diagnosed based on characteristic retinal lesions and supported by positive serologic testing using commercial enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

A total of 390 subjects aged 10-100 years (mean age 47 years) were examined; 118 (30.3%) were male and 272 (69.7%) female. Ten subjects (6 females and 4 males) had toxoplasmic ocular lesions (prevalence 2.6%). Of these, two had bilateral lesions and eight had unilateral lesions. Subjects with toxoplasmic ocular lesions were older than those without lesions (p = 0.028). The development of ocular toxoplasmosis was not associated with rural dwelling, sex, keeping cats, or consumption of meat.

CONCLUSION

The prevalence of ocular toxoplasmosis in our Ghanaian study population was lower than findings from Southern Brazil, where there is a similar prevalence of infection in the general population.

A Brazilian report using serological and molecular diagnosis to monitoring acute ocular toxoplasmosis

Background

Toxoplasmosis was recently included as a neglected disease by the Center for Disease Control. Ocular toxoplasmosis is one clinical presentation of congenital or acquired infection. The laboratory diagnosis is being used worldwide to support the clinical diagnosis and imaging. The aim of this study was to evaluate the use of serology and molecular methods to monitor acute OT in immunocompetent patients during treatment.

Methods

Five immunocompetent patients were clinically diagnosed with acute OT. The clinical evaluation was performed by ophthalmologic examination using the Early Treatment Diabetic Retinopathy Study, best-corrected visual acuity, slit lamp biomicroscopy, fundoscopic examination with indirect binocular ophthalmoscopy color fundus photography, fluorescein angiography and spectral optical coherence tomography (OCT). Serology were performed by ELISA (IgA, IgM, IgG) and confirmed by ELFA (IgG, IgM). Molecular diagnoses were performed in peripheral blood by cPCR using the Toxoplasma gondiiB1 gene as the marker. Follow-up exams were performed on day +15 and day +45.

Results

Only five non-immunocompromised male patients completed the follow up and their data were used for analysis. The mean age was 41.2 ± 11.3 years (median: 35; range 31–54 years). All of them were positive for IgG antibodies but with different profiles for IgM and IgA, as well as PCR. For all patients the OCT exam showed active lesions with the inner retinal layers being abnormally hyper-reflective with full-thickness disorganization of the retinal reflective layers, which assumed a blurred reflective appearance and the retina was thickened.

Conclusions

The presence of IgA and IgM confirmed the acute infection and thus was in agreement with the clinical evaluation. Our results show the adopted treatment modified the serological profile of IgM antibodies and the PCR results, but not the IgG and IgA antibodies and that imaging is a good tool to follow-up patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-015-1650-6) contains supplementary material, which is available to authorized users.

CCp5A Protein from Toxoplasma gondii as a Serological Marker of Oocyst-driven Infections in Humans and Domestic Animals

Considering that the current immunoassays are not able to distinguish the infective forms that cause Toxoplasma gondii infection, the present study was carried out to evaluate the reactivity of two recombinant proteins (CCp5A and OWP1) from oocyst/sporozoite, in order to differentiate infections occurring by ingestion of oocysts or tissue cysts. The reactivity of the recombinant proteins was assessed against panels of serum samples from animals (chickens, pigs, and mice) that were naturally or experimentally infected by different infective stages of the parasite. Also, we tested sera from humans who have been infected by oocysts during a well-characterized toxoplasmosis outbreak, as well as sera from pregnant women tested IgM⁺/IgG⁺ for T. gondii, which source of infection was unknown. Only the sporozoite-specific CCp5A protein was able to differentiate the parasite stage that infected chickens, pigs and mice, with specific reactivity for oocyst-infected animals. Furthermore, the CCp5A showed preferential reactivity for recent infection by oocyst/sporozoite in pigs and mice. In humans, CCp5A showed higher reactivity with serum samples from the outbreak, compared with serum from pregnant women. Altogether, these findings demonstrate the usefulness of the CCp5A protein as a new tool to identify the parasite stage of T. gondii infection, allowing its application for diagnosis and epidemiological investigations in animals and humans. The identification of parasite infective stage can help to design effective strategies to minimize severe complications in immunocompromised people and, particularly, in pregnant women to prevent congenital infection.

Serological diagnosis of Toxoplasma gondii infection: Recommendations from the French National Reference Center for Toxoplasmosis

Toxoplasmosis manifests no clinical signs in 80% of cases in immunocompetent patient, causing immunization characterized by the persistence of cysts, particularly in brain, muscles, and retina. Assessing the serological status, based on testing for serum toxoplasma IgG and IgM antibodies, is essential in cases that are increasingly at risk for the more severe disease forms, such as congenital or ocular toxoplasmosis. This disease also exposes immunosuppressed patients to reactivation, which can lead to more widespread forms and increased mortality. By interpreting the serological results, we can estimate the risk of contamination or reactivation and define appropriate prophylactic and preventive measures, such as hygienic and dietetic, therapeutic, biological, and clinical follow-up, according to the clinical context. We hereby propose practical approaches based on serological data, resulting from a consensus of a group of experts from the French National Reference Center Network for Toxoplasmosis, according to both routine and specific clinical situations.

Current Therapy of Acquired Ocular Toxoplasmosis: A Review

Caused by the parasite Toxoplasma gondii, ocular toxoplasmosis (OT) is the most common form of posterior infectious uveitis. Combined antiparasitic therapy is the standard treatment for OT, but several other schemes have been proposed. The purpose of the present study was to review the literature on the treatment of OT and provide ophthalmologists with up-to-date information to help reduce OT-related visual morbidity. In conclusion, no ideal treatment scheme was identified; currently prescribed therapeutic schemes yield statistically similar functional outcomes.

Ocular Involvement Following Postnatally Acquired Toxoplasma gondii Infection in Southern Brazil: A 28-Year Experience

PURPOSE

To determine the incidence of, and risk factors for, ocular involvement among people known to have postnatally acquired Toxoplasma gondii infection in a region of southern Brazil where there is a high prevalence of endemic disease.

DESIGN

Retrospective longitudinal cohort study.

METHODS

Records of 302 patients with serologic evidence of recent T gondii infection (a positive anti-T gondii IgM antibody test) from Erechim, Rio Grande do Sul state, Brazil (1974-2002) were analyzed. The incidence of ocular involvement was calculated in terms of person-years (PY) of follow-up. Risk factors for ocular involvement were analyzed using log-rank and Fisher exact tests.

RESULTS

At initial ocular examination (baseline), 30 patients (9.9%) had intraocular inflammation only (anterior chamber cells and flare, vitreous inflammatory reactions, retinal whitening), without clinically apparent necrotizing retinochoroiditis. At baseline, men were more likely to have ocular involvement (P = .043) and antiparasitic treatment was associated with less ocular involvement (P = .015). Follow-up examinations were performed on 255 patients (median follow-up, 13.7 months [range 0.4-261.9 months]). Among those without ocular involvement at baseline, the incidence of necrotizing retinochoroiditis was 6.4/100 PY. Patients >40 years of age at first IgM test had a greater risk of incident necrotizing retinochoroiditis (hazard ratio = 4.47, 95% CI = 1.67-11.93, P = .003) than younger patients. The incidence of recurrent necrotizing retinochoroiditis was 10.5/100 PY.

CONCLUSION

Isolated intraocular inflammatory reactions can be an initial manifestation of T gondii infection, with necrotizing retinochoroiditis occurring months or years later. Male sex and older age are risk factors for toxoplasmic retinochoroiditis. Antitoxoplasmic treatment may protect against early ocular involvement.

Ocular Involvement Following an Epidemic of Toxoplasma gondii Infection in Santa Isabel do Ivaí, Brazil

PURPOSE

To investigate ocular involvement (prevalence, incidence, lesion characteristics) following postnatally acquired infection with an "atypical" genotype of Toxoplasma gondii during a well-characterized 2001 outbreak in Santa Isabel do Ivaí, Brazil, attributed to a contaminated municipal reservoir.

DESIGN

Prospective longitudinal cohort study.

METHODS

We performed ophthalmic examinations on 290 of 454 individuals with serologic evidence of T gondii infection during the epidemic (positive IgM antibody tests). Prevalence of ophthalmic findings (intraocular inflammatory reactions [including transient, isolated retinal whitening without clinically apparent retinal necrosis] and necrotizing retinochoroiditis) at initial examination (baseline) and incidence of new findings during 10.5 months of follow-up were calculated. Cumulative risks of ophthalmic events were determined (Kaplan-Meier technique).

RESULTS

Ocular involvement was present in 33 of 288 IgM+ individuals (11.5%) at baseline, including 17 with focal retinal whitening only and 13 with necrotizing retinochoroiditis. Incidence of new ocular involvement was estimated to be 1.73 events per 100 person-months (PM); cumulative risk at 10.5 months was 30.1%. Incident necrotizing retinochoroiditis was more common among those with focal retinal whitening at baseline (6.7/100 PM) than among those with no ocular involvement at baseline (1.11/100 PM; hazard ratio 6.07 [1.94-19.01]; P < .0001).

CONCLUSIONS

Waterborne infection with an atypical genotype of T gondii is associated with substantial risk of ocular involvement. Lesions may continue to develop during the first year after infection. The increased risk of late necrotizing retinochoroiditis associated with isolated focal retinal whitening at presentation suggests the early presence of parasites in the retina, despite initial lack of observable retinal necrosis.

Strain hypothesis of Toxoplasma gondii infection on the outcome of human diseases

The intracellular protozoan Toxoplasma gondii is an exceptionally successful food and waterborne parasite that infects approximately 1 billion people worldwide. Genotyping of T. gondii isolates from all continents revealed a complex population structure. Recent research supports the notion that T. gondii genotype may be associated with disease severity. Here, we (1) discuss molecular and serological approaches for designation of T. gondii strain type, (2) overview the literatures on the association of T. gondii strain type and the outcome of human disease and (3) explore possible mechanisms underlying these strain-specific pathology and severity of human toxoplasmosis. Although no final conclusions can be drawn, it is clear that virulent strains (e.g. strains containing type I or atypical alleles) are significantly more often associated with increased frequency and severity of human toxoplasmosis. The significance of highly virulent strains can cause severe diseases in immunocompetent patients and might implicated in brain disorders such as schizophrenia should led to reconsideration of toxoplasmosis. Further studies that combine parasite strain typing and human factor analysis (e.g. immune status and genetic background) are required for better understanding of human susceptibility or resistance to toxoplasmosis.

Yeast three-hybrid screen identifies TgBRADIN/GRA24 as a negative regulator of Toxoplasma gondii bradyzoite differentiation

Differentiation of the protozoan parasite Toxoplasma gondii into its latent bradyzoite stage is a key event in the parasite's life cycle. Compound 2 is an imidazopyridine that was previously shown to inhibit the parasite lytic cycle, in part through inhibition of parasite cGMP-dependent protein kinase. We show here that Compound 2 can also enhance parasite differentiation, and we use yeast three-hybrid analysis to identify TgBRADIN/GRA24 as a parasite protein that interacts directly or indirectly with the compound. Disruption of the TgBRADIN/GRA24 gene leads to enhanced differentiation of the parasite, and the TgBRADIN/GRA24 knockout parasites show decreased susceptibility to the differentiation-enhancing effects of Compound 2. This study represents the first use of yeast three-hybrid analysis to study small-molecule mechanism of action in any pathogenic microorganism, and it identifies a previously unrecognized inhibitor of differentiation in T. gondii. A better understanding of the proteins and mechanisms regulating T. gondii differentiation will enable new approaches to preventing the establishment of chronic infection in this important human pathogen.

Acute unilateral toxoplasma retinochoroiditis associated with adalimumab, a tumor necrosis factor-α antagonist

PURPOSE

The purpose of this study was to report a case of a patient with unilateral toxoplasma retinochoroiditis while on treatment with adalimumab, an anti-tumor necrosis factor α agent for ulcerative colitis.

METHODS

This is a descriptive case report.

RESULTS AND DISCUSSION

In addition to the patient with toxoplasma retinochoroiditis, there is one published report of two patients who developed toxoplasma chorioretinitis while on anti-tumor necrosis factor α therapy for rheumatoid arthritis: one was on adalimumab and methotrexate and the other one was on etanercept and methotrexate.

CONCLUSION

The authors need to be aware of this potentially vision threatening risk with anti-tumor necrosis factor α therapy.

Striking Divergence in Toxoplasma ROP16 Nucleotide Sequences From Human and Meat Samples

BACKGROUND

ROP16 is a protein kinase of Toxoplasma gondii identified in the mouse model as a virulent marker, but it is unknown whether this finding is relevant in human toxoplasmosis.

METHODS

We obtained the Toxoplasma ROP16 locus DNA sequence in samples from 12 patients with ocular toxoplasmosis, 1 sample from a patient with congenital toxoplasmosis, 22 samples from soldiers operating in the jungle, 2 samples from urban soldiers, and 10 samples from meat for human consumption. An enzyme-linked immunosorbent assay specific for antibodies against the ROP16 mouse-virulent peptide was performed in 46 serum specimens from patients with ocular toxoplasmosis and in 28 serum specimens from patients with chronic asymptomatic infection, of whom 19 had congenital infection and 11 had toxoplasmic lymphadenitis.

RESULTS

We found a striking divergence of the ROP16 nucleotide sequences. Ten of 12 sequences (83.3%) from patients with ocular toxoplasmosis clustered with those of mouse-virulent strains, whereas 7 of 7 ROP16 sequences (100%) from meat were clustered with those of mouse-avirulent strains. Only 11 of 104 serum specimens (10.5%) had specific antibodies against the mouse-virulent peptide, and there was no association between clinical forms and positive results of serological assays.

CONCLUSIONS

The majority of ROP16 nucleotide sequences from Colombian patients with ocular toxoplasmosis belonged to the group of mouse-virulent strains.

Drinking water source and human Toxoplasma gondii infection in the United States: a cross-sectional analysis of NHANES data

BACKGROUND

Toxoplasma gondii imparts a considerable burden to public health. Human toxoplasmosis can be life-threatening in immunocompromised individuals, has been associated with psychiatric disorders, and can cause severe congenital pathologies, spontaneous abortion, or stillbirth. Environmental modes of transmission contributing to the incidence of human toxoplasmosis are poorly understood. We sought to examine National Health and Nutrition Examination Survey (NHANES) data for risk factors associated with T. gondii seroprevalence.

METHODS

T. gondii serology results reported for Continuous NHANES survey years 1999-2004 and 2009-10 were examined. To explore associations with toxoplasmosis seropositivity, covariates of interest were selected a priori, including source and home treatment of tap water. Associations between potential risk factors and evidence of IgG antibodies against T. gondii were assessed using multivariable logistic regression.

RESULTS

Among 23,030 participants with available T. gondii serology across 8 years of continuous NHANES survey data (1999-2004; 2009-2010), persons born outside the United States were significantly more likely to be seropositive, and seropositivity was inversely associated with years spent in the United States. Among US-born participants, participants with homes on well water (both those who used at-home water treatment devices and those who did not), as well as participants with public/private company-provided tap water who did not use at-home water treatment devices, were significantly more likely to be seropositive compared to participants who used home treatment devices on tap water provided by a private or public water company. A comparative subpopulation analysis revealed age-adjusted seroprevalence among US-born persons 12-49 yrs old significantly declined to 6.6% (95% CI, 5.2-8.0) (P <0.0001) in 2009-10, compared to previously published reports for NHANES data from 1988-1994 (14.1%) and 1999-2004 (9.0%).

CONCLUSIONS

Data suggests that T. gondii infections continue to decline in the United States, but the overall infection rate remains substantial at nearly 7%. Despite the limitations in the Continuous NHANES cross-sectional survey, the association between well water use and T. gondii infection warrants further research.

Case report of a neonate with ocular toxoplasmosis due to congenital infection: estimation of the percentage of ocular toxoplasmosis in Greece caused by congenital or acquired infection

We report a case of a newborn male child with congenital toxoplasmosis. During pregnancy seroconversion occurred and positive titers of antitoxoplasmic antibodies (immunoglobulin M and G) were found in the mother, in the third trimester. She received treatment with spiramycin. After birth, the neonate presented with chorioretinitis and intracranial calcifications. The neonate received treatment with pyrimethamine, sulfadiazine, and leucovorin for 1 year. In addition to using a previously described method, we report for the first time in Greece an estimation regarding the percentage of ocular toxoplasmosis caused by congenital or acquired infection. We estimate that ocular toxoplasmosis in Greece is caused in 7% of the cases by congenital infection, and in 93% of the cases by acquired infection.

Severe South American ocular toxoplasmosis is associated with decreased Ifn-γ/Il-17a and increased Il-6/Il-13 intraocular levels

In a cross sectional study, 19 French and 23 Colombian cases of confirmed active ocular toxoplasmosis (OT) were evaluated. The objective was to compare clinical, parasitological and immunological responses and relate them to the infecting strains. A complete ocular examination was performed in each patient. The infecting strain was characterized by genotyping when intraocular Toxoplasma DNA was detectable, as well as by peptide-specific serotyping for each patient. To characterize the immune response, we assessed Toxoplasma protein recognition patterns by intraocular antibodies and the intraocular profile of cytokines, chemokines and growth factors. Significant differences were found for size of active lesions, unilateral macular involvement, unilateral visual impairment, vitreous inflammation, synechiae, and vasculitis, with higher values observed throughout for Colombian patients. Multilocus PCR-DNA sequence genotyping was only successful in three Colombian patients revealing one type I and two atypical strains. The Colombian OT patients possessed heterogeneous atypical serotypes whereas the French were uniformly reactive to type II strain peptides. The protein patterns recognized by intraocular antibodies and the cytokine patterns were strikingly different between the two populations. Intraocular IFN-γ and IL-17 expression was lower, while higher levels of IL-13 and IL-6 were detected in aqueous humor of Colombian patients. Our results are consistent with the hypothesis that South American strains may cause more severe OT due to an inhibition of the protective effect of IFN-γ.

A rapid diagnostic test for toxoplasmosis using recombinant antigenic N-terminal half of SAG1 linked with intrinsically unstructured domain of gra2 protein

Toxoplasma gondii is an apicomplexan parasite with a broad host range of most warm-blooded mammals including humans, of which one-thirds of the human population has been infected worldwide which can cause congenital defects, abortion, and neonatal complications. Here, we developed a rapid diagnostic test (RDT) for T. gondii infection. Antigenic N-terminal half of the major surface antigen (SAG1) was linked with intrinsically unstructured domain (IUD) of dense granule protein 2 (GRA2). The recombinant GST-GRA2-SAG1A protein was successfully expressed and purified as 51 kDa of molecular weight. Furthermore, antigenicity and solubility of the rGST-GRA2-SAG1A protein were significantly increased. The overall specificity and sensitivity of GST-GRA2-SAG1A loaded RDT (TgRDT) were estimated as 100% and 97.1% by comparing with ELISA result which uses T. gondii whole cell lysates as the antigen. The TgRDT tested with Uganda people sera for field trial and showed 31.9% of seroprevalence against T. gondii antibody. The TgRDT is proved to be a kit for rapid and easy to use with high accuracy, which would be a suitable serodiagnostic tool for toxoplasmosis.

Long-term consequences of foodborne infections

Foodborne infections with Campylobacter, E. coli O157:H7, Listeria monocytogenes, Salmonella, Shigella, Toxoplasma gondii, and other pathogens can result in long-term sequelae to numerous organ systems. These include irritable bowel syndrome, inflammatory bowel disease, reactive arthritis, hemolytic uremic syndrome, chronic kidney disease, Guillain-Barré Syndrome, neurological disorders from acquired and congenital listeriosis and toxoplasmosis, and cognitive and developmental deficits due to diarrheal malnutrition or severe acute illness. A full understanding of the long-term sequelae of foodborne infection is important both for individual patient management by clinicians, as well as to inform food safety and public health decision making.

Ocular manifestations of systemic disease: toxoplasmosis

PURPOSE OF REVIEW

To provide an overview of ocular toxoplasmosis, the leading cause of infectious posterior uveitis, focusing on recent trends of disease epidemiology, pathogenesis, diagnosis, therapy and prevention.

RECENT FINDINGS

Novel aspects of epidemiology, including growing importance of water transmission are discussed. The historical controversy of congenital versus postnatally acquired toxoplasmosis is revisited. Recent insights into pathogenesis of ocular toxoplasmosis are also reviewed, tipping the delicate balance between parasite virulence and host immunity. Diagnosis of ocular toxoplasmosis is also discussed in the light of serological, molecular and imaging tools. Finally, a critical analysis of current and emerging therapies for ocular toxoplasmosis is made. Preventive aspects are also commented upon.

SUMMARY

Waterborne toxoplasmosis is increasingly recognized in outbreaks and in endemic areas. The importance of postnatally acquired toxoplasmosis is now well established, but should not lead to underestimation of congenital disease. Genetic determination of parasite virulence/individual susceptibility might correlate with disease outcomes. Serological, molecular and imaging tools may improve the diagnosis and follow-up of individuals with ocular toxoplasmosis. Despite emergence of alternative therapeutic regimens, including intravitreal antibiotics, classical therapy with sulfadiazine/pyrimethamine is still standard for toxoplasmic retinochoroiditis. Adequate prophylaxis is expected to have an effect in ocular burden of toxoplasmosis.

The impact of the waterborne transmission of Toxoplasma gondii and analysis efforts for water detection: an overview and update

The ubiquitous protozoa Toxoplasma gondii is now the subject of renewed interest, due to the spread of oocysts via water causing waterborne outbreaks of toxoplasmosis in different parts of the world. This overview discusses the different methods for detection of Toxoplasma in drinking and environmental water. It includes a combination of conventional and molecular tools for effective oocyst recovery and detection in water sources as well as factors hindering the detection of this parasite and shedding light on a promising new molecular assay for the diagnosis of Toxoplasma in environmental samples. Hopefully, this attempt will facilitate future approaches for better recovery, concentration, and detection of Toxoplasma oocysts in environmental waters.