Cuban Ocular Toxoplasmosis Epidemiology Study (COTES): incidence and prevalence of ocular toxoplasmosis in Central Cuba

Prevalence of Ocular Toxoplasmosis in the General Population and Uveitis Patients: A Systematic Review and Meta-Analysis

PURPOSE

The present study aimed to estimate the global prevalence of ocular toxoplasmosis in the general population and patients with uveitis.

METHODS

Four electronic databases were searched and 130 studies for evaluating the prevalence of OT among the general population and uveitis patients were included.

RESULTS

The pooled prevalence of OT among the general population was estimated at 2% (95% CI, 2-3%; 762/486 051). The highest prevalence rate was observed in America 6% (95% CI, 1-11%). In uveitis patients, a prevalence rate of 9% (95% CI, 8-10%; 5668/88 006) was reported. The countries with a lower middle income had higher prevalence rates. The prevalence of OT in posterior uveitis 33% (95%CI, 24-42%) was substantially higher than in panuveitis 7% (95% CI, 5-8%).

CONCLUSION

Our results provide a new perspective on the prevalence of OT. Knowledge of international and regional patterns of disease is essential for the establishment of precise diagnostic protocols and control programs.

Clinical Insights: Antimicrobial Therapy for Infectious Uveitis

Infectious uveitis is a major global cause of vision impairment. Despite the eye's immune privilege, afforded by the blood-ocular barrier that restricts microbial entry, several pathogens such as bacteria, viruses, fungi, and parasites can still infiltrate and cause ocular infections and complications. Clinicians often encounter significant challenges in treating infectious uveitis due to limited or ineffective treatment options. Modern molecular techniques and imaging can aid in diagnosing and assessing intraocular infections. Various antimicrobial therapies exist, spanning topical and systemic treatments, but these are constrained by issues like drug concentration, penetration, effective duration, toxicity, and side effects. Treatment approaches also differ based on the infection's etiology. This review provides recent updates on antimicrobial therapies from a clinical perspective, covering topical, systemic, and regional treatments for infectious uveitis.

The Decreased Treg Cells Number Associated with Retinal Lesion Size in Ocular Toxoplasmosis

Introduction

The imbalance of the immune response is an important factor contributing to the incidence of ocular toxoplasmosis (OT). Regulatory T cells (Treg) play a key role in maintaining the balance between Th1 and Th17 immune responses, while interleukin-27 (IL-27) levels are related to the differentiation of Th17 cells. This study analyzes the differences in the number of Treg cells and the level of IL-27 between OT patients and seropositive individuals without ocular lesions and its correlation with retinal lesion size.

Methods

This analytic observational study, conducted for 8 months, involved 11 OT patients and 10 seropositive individuals without ocular lesions. All subjects underwent a comprehensive ophthalmological examination. Retinal lesions were documented by fundus photographs and the size was measured using Digimizer 4.2.2.0 software. Isolation of peripheral blood mononuclear cells (PBMC) was performed to measure the number of Treg cells using flow cytometry and interleukin-27 levels were assessed using the Sandwich enzyme-linked immunosorbent assay (ELISA) technique. Data were analyzed with SPSS.

Result

The number of Treg cells in the OT group (47.16 ± 15.66%) was lower than in the seropositive group without the ocular lesions (62.86 ± 17.08%) (p = 0.029). The serum IL-27 levels in the OT group were not significantly different from the seropositive group without the ocular lesions (p = 0.360). The number of Treg cells was significantly related to retinal lesion size (p = 0.043), with a correlation coefficient of -0.648, indicating a strong and inverse correlation. There was no significant correlation between serum IL-27 levels and retinal lesion size (p = 0.556).

Conclusion

Ocular toxoplasmosis patients have a low number of Treg cells that are inversely related to the retinal lesion size. The size of the retinal lesion increases as the number of Treg cells decreases.

Clinical and Serological Characteristics of Ocular Toxoplasmosis in the Democratic Republic of Congo

PURPOSE

To describe demographic data, clinical features, and serological profiles in a cohort of Congolese patients with ocular toxoplasmosis (OT).

METHOD

Cross-sectional study, carried out between March 2020 and July 2021 in two ophthalmic clinics in Kinshasa.

RESULTS

The study comprised 95 participants with OT. Fifty-three patients were male (55.8%). The mean age at presentation was 35.6 ± 14.1 years (range 8-69 years); 71 had active OT (74.7%), among them, 33 had primary OT (46.5%), and 38 had recurrences (53.5%). At presentation, 51 patients (53.7%) had visual impairment (VA < 6/18). Retinochoroidal lesions were located in the central retina in 60 patients (63.1%). Patients with primary OT tend to have higher IgG levels than those with recurrent OT (P = .01).

CONCLUSION

We report the largest cohort of patients with OT in sub-Saharan Africa. In our setting, most patients had recurrent OT with multiple, extensive, and central retinochoroidal lesions.

Protein kinases on carbon metabolism: potential targets for alternative chemotherapies against toxoplasmosis

The apicomplexan parasite Toxoplasma gondii is the causative agent of toxoplasmosis, a global disease that significantly impacts human health. The clinical manifestations are mainly observed in immunocompromised patients, including ocular damage and neuronal alterations leading to psychiatric disorders. The congenital infection leads to miscarriage or severe alterations in the development of newborns. The conventional treatment is limited to the acute phase of illness, without effects in latent parasites; consequently, a cure is not available yet. Furthermore, considerable toxic effects and long-term therapy contribute to high treatment abandonment rates. The investigation of exclusive parasite pathways would provide new drug targets for more effective therapies, eliminating or reducing the side effects of conventional pharmacological approaches. Protein kinases (PKs) have emerged as promising targets for developing specific inhibitors with high selectivity and efficiency against diseases. Studies in T. gondii have indicated the presence of exclusive PKs without homologs in human cells, which could become important targets for developing new drugs. Knockout of specific kinases linked to energy metabolism have shown to impair the parasite development, reinforcing the essentiality of these enzymes in parasite metabolism. In addition, the specificities found in the PKs that regulate the energy metabolism in this parasite could bring new perspectives for safer and more efficient therapies for treating toxoplasmosis. Therefore, this review provides an overview of the limitations for reaching an efficient treatment and explores the role of PKs in regulating carbon metabolism in Toxoplasma, discussing their potential as targets for more applied and efficient pharmacological approaches.

The disease burden of ocular toxoplasmosis in Denmark in 2019: Estimates based on laboratory testing of ocular samples and on publicly available register data

Background

Toxoplasma gondii is an important zoonotic protozoan parasite with worldwide distribution. Information on the contribution of ocular toxoplasmosis to the disease burden caused by this parasite is limited or lacking from many countries.

Methods

We estimated the minimum occurrence of ocular toxoplasmosis in Denmark using results from direct detection of T. gondii DNA with qPCR and determination of the Goldmann-Witmer coefficient on ocular samples submitted by ophthalmological clinics and departments to the national reference laboratory in 2003–2019. In addition, we inferred incidence estimates using retrospective data that are publicly available in the National Patient Register, and we used unstructured expert elicitation as the basis for sensitivity analyses. We estimated the disease burden of ocular toxoplasmosis in 2019 in disability-adjusted life years (DALYs).

Findings

Ocular samples from 263 individuals (median age 57 years, range 2–88) had been tested with at least one of the methods during 2003–2019, and 42 (16%) tested positive (median age 65 years, range 14–85). In 2019, five (16%) of 31 tested individuals were positive, giving a minimum annual incidence estimate of 0.09 per 100.000 population. From this, we calculated a disease burden of at least 4 DALYs (95% confidence interval, 3–5). The age range suggested that this figure represented postnatally acquired ocular toxoplasmosis. The disease burden of ocular toxoplasmosis due to congenital toxoplasmosis has been previously estimated to be at least 12 DALYs, resulting in an estimated minimum total disease burden due to ocular toxoplasmosis of 16 DALYs. In 2005–2018, the mean annual number of diagnoses of ocular toxoplasmosis reported to the National Patient Register was 186, and the corresponding disease burden estimate was 134 DALYs (95% confidence interval, 113–158). Sensitivity analyses focusing on incidence and severity resulted in disease burden estimates in the range of 9–523 DALYs.

Interpretation

Because most diagnoses of ocular toxoplasmosis are based on clinical observations, ophthalmoscopy, and serology without confirmatory testing, the disease burden caused by ocular toxoplasmosis is likely substantially higher than our minimum estimates. Our results indicate that ocular toxoplasmosis contributes to the disease burden caused by T. gondii in Denmark, but uncertainty about the incidence and severity precludes reliable estimation of its importance.

Seroprevalence of Toxoplasma gondii and associated risk factors in domestic pigs raised from Cuba

A cross-sectional study was carried out to determine the seroprevalence of Toxoplasma gondii and associated risk factors in pigs in the largest pork-producing region in Cuba. Serum samples from 420 pigs, including 210 sows and 210 post-weaning pigs, were tested for antibodies against T. gondii using a commercial indirect enzyme-linked immunosorbent assay. Anti-T. gondii antibodies were detected in 56 animals (13.3%, 95% CI: 10.1–16.6). A generalized estimating equations model revealed that the risk factors associated with higher seropositivity in pigs were altitude (higher in farm’s location < 250 m above sea level (masl) versus ≥ 250 masl) and age (higher in sows compared to post-weaning pigs). The results indicated that this protozoan parasite is widely distributed on pig farms in the study area, which is a public health concern since the consumption of raw or undercooked pork meat products containing tissue cysts is considered one of the main routes of T. gondii transmission worldwide. Control measures should be implemented to reduce the risk of exposure to T. gondii in pigs in Cuba.

Frequency and visual outcomes of ocular toxoplasmosis in an adult Brazilian population

Although ocular toxoplasmosis is a leading cause of posterior uveitis worldwide, there is scarce information about the real-life frequency of ocular lesions, visual outcomes, and risk factors for poor prognosis. We conducted a community-based cross-sectional study with 721 adults living in Cássia dos Coqueiros, Southeast Brazil, consisted of visual acuity measurement, dilated ocular examination, a risk-factor questionnaire, and peripheral blood collection for anti-T. gondii serology. Presumed toxoplasmic lesions were recorded on video and analyzed by experienced and masked ophthalmologists. Ocular toxoplasmosis was determined if at least one suspected lesion was appointed by two graders in the presence of positive anti-T. gondii serology. Forty-eight eyes (n = 42 participants; 6.7% among those with positive anti-T. gondii serology) with ocular toxoplasmosis were found. Most lesions were single (n = 28; 58.3%), peripheral (n = 34; 77.1%) and unilateral (85.7% of participants); no active lesions were found. Older age was associated with lesions larger than one-disc diameter (p = 0.047), and lower social stratum (OR: 2.89; CI 1.2-6.97; p = 0.018) was associated with the presence of toxoplasmic lesions. Although there were no differences in visual acuity between participants and eyes with or without ocular lesions (p > 0.05), unilateral blindness associated with ocular toxoplasmosis was identified in a reduced number of individuals.

Ocular toxoplasmosis: background and evidence for an antibiotic prophylaxis

PURPOSE OF REVIEW

The purpose of this review was to provide an overview of current data on antibiotic prophylaxis in ocular toxoplasmosis.

RECENT FINDINGS

Studies showing the prophylactic effect of long-term antibiotics are discussed. Prophylaxis seems to be justified in patients with a high risk of recurrence because of antibiotic's potential side-effects. Therefore, predisposing factors leading to a higher risk of recurrence and the time period during which an antibiotic prophylaxis is most appropriate are reviewed. Finally, a patient-individualized treatment recommendation is summarized.

SUMMARY

In the current literature, two prospective, randomized case-control studies exist, which show the protective effect of an antibiotic prophylaxis. Hematologic, gastrointestinal and dermatologic complications are potential side-effects. Especially during the first year after suffering a recurrence, an antibiotic prophylaxis seems to be justified. The risk of a recurrence is inter alia influenced by the duration of the disease, the immune status of the host and the patient's age. Therefore, an antibiotic prophylaxis should be considered for patients who have recently been infected with ocular toxoplasmosis, for middle-aged and elderly patients and patients with a compromised immune system. This should be discussed with each patient individually, especially if the lesion is close to the macula.

MHC Class I Chain-Related Gene A Polymorphisms and Linkage Disequilibrium with HLA-B and HLA-C Alleles in Ocular Toxoplasmosis

This study investigated whether polymorphisms of the MICA (major histocompatibility complex class I chain-related gene A) gene are associated with eye lesions due to Toxoplasma gondii infection in a group of immunocompetent patients from southeastern Brazil. The study enrolled 297 patients with serological diagnosis of toxoplasmosis. Participants were classified into two distinct groups after conducting fundoscopic exams according to the presence (n = 148) or absence (n = 149) of ocular scars/lesions due to toxoplasmosis. The group of patients with scars/lesions was further subdivided into two groups according to the type of the ocular manifestation observed: primary (n = 120) or recurrent (n = 28). Genotyping of the MICA and HLA alleles was performed by the polymerase chain reaction-sequence specific oligonucleotide technique (PCR-SSO; One Lambda®) and the MICA-129 polymorphism (rs1051792) was identified by nested polymerase chain reaction (PCR-RFLP). Significant associations involving MICA polymorphisms were not found. Although the MICA*002~HLA-B*35 haplotype was associated with increased risk of developing ocular toxoplasmosis (P-value = 0.04; OR = 2.20; 95% CI = 1.05–4.60), and the MICA*008~HLA-C*07 haplotype was associated with protection against the development of manifestations of ocular toxoplasmosis (P-value = 0.009; OR: 0.44; 95% CI: 0.22–0.76), these associations were not statistically significant after adjusting for multiple comparisons. MICA polymorphisms do not appear to influence the development of ocular lesions in patients diagnosed with toxoplasmosis in this study population.