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

Immune system roles in pathogenesis, prognosis, control, and treatment of Toxoplasma gondii infection

Toxoplasma gondii is the protozoan causative agent of toxoplasmosis in humans and warm-blooded animals. Recent studies have illustrated that the immune system plays a pivotal role in the pathogenesis of toxoplasmosis by triggering immune cytokines like IL-12, TNF-α, and IFN-γ and immune cells like DCs, Th1, and Th17. On the other hand, some immune components can serve as prognosis markers of toxoplasmosis. In healthy people, the disease is often asymptomatic, but immunocompromised people and newborns may suffer severe symptoms and complications. Therefore, the immune prognostic markers may provide tools to measure the disease progress and help patients to avoid further complications. Immunotherapies using monoclonal antibody, cytokines, immune cells, exosomes, novel vaccines, and anti-inflammatory molecules open new horizon for toxoplasmosis treatment. In this review article, we discussed the immunopathogenesis, prognosis, and immunotherapy of Toxoplasma gondii infection.

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.

Screening for common eye diseases in the elderly with Optos ultra-wide-field scanning laser ophthalmoscopy: a pilot study with focus on ocular toxoplasmosis

Purpose

Studies on the occurrence of ocular toxoplasmosis (OT) in a general population are rare. Therefore, we conducted this pilot study to assess whether a nonmydriatic ultra-wide-field (UWF) scanning laser ophthalmoscope (SLO) is suitable for a simple, rapid screening procedure.

Methods

The population of this cross-sectional study was randomly recruited from a cohort of hospital-based patients in an urban geriatric hospital. Ophthalmologic evaluation was performed on 201 eyes from 101 participants through nonmydriatic UWF-SLO (Optos Daytona) and assessed for suspicious lesions and other relevant ocular findings. All images were evaluated by two independent examiners. Individuals who presented lesions with a morphological appearance suggestive of OT underwent fundoscopy and serological analysis of Toxoplasma gondii-specific antibodies.

Results

The mean age of the study group was 76 years, and 63 (62%) were female. Despite many health restrictions, the SLO examination was carried out easily in this geriatric population. Three participants presented findings by SLO suspicious for T. gondii-related injury. Further clinical examination and serological investigation confirmed the diagnosis, with funduscopic evaluation and positive T. gondii ELISA testing. In addition, a high rate of arterial hypertension and dyslipidemias within the cohort led to a high incidence of vascular changes and age-related fundus findings.

Conclusion

In our study, we confirm that UWF-SLO technology is helpful in the rapid detection of peripheral retinal injuries in elderly patients such as OT and may be used as a routine screening tool.

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.