The Value of the Antibody Detection in the Diagnosis of Ocular Toxocariasis and the Aqueous Cytokine Profile Associated With the Condition

Neurobehavioral Disorders and Pathological Changes in the Brain of Mice Are Caused by Chronic Toxocara canis Larval Invasion with Low to Moderate Inoculum

Toxocara canis larvae are one of the most overlooked agents of nervous system infection in paratenic hosts. Previous studies in mouse models have shown that infection with various (mainly high) numbers of larvae leads to neurobehavioral disturbances and pathological changes. Our study investigated whether the infection with low and moderate numbers of larvae could affect the physical condition, motor skills, and pathogenesis in the brains of experimentally infected mice.Two groups of BALB/c mice were orally infected with 10 and 100 T. canis larvae per animal and examined regularly until the 97th week after infection. General appearance, specific antibody responses, and motor/balance skills were assessed. The number and viability of larvae in the liver, spleen, lungs, and brain were assessed by quantitative compressed biopsy technique, while the pathological changes of the brain infection were studied histologically.As a result, changes were observed in overall appearance, activity, as well as motor and balance ability. The infections were associated with an increased IgG antibody response to the specific anti-T. canis excretory/secretory antigen and tissue damage in the brain characterized by necrosis, cell infiltrations, including foamy cells, and hemorrhages.The study demonstrated the effects of low and moderate T. canis infection in a paratenic host during the chronic phase of infection, which lasted up to 97 weeks for the first time.

Ocular Toxocariasis in Adult Caucasian Patients: Clinical Presentations and Treatment Outcomes

PURPOSE

To report the clinical features and treatment outcomes in adult Caucasians with ocular toxocariasis (OT) and investigate their prognosis depending on their serological status.

METHODS

Retrospective observational cohort study (2016-2021) including consecutive adults with uveitis and positive western blot (WB) in the aqueous humor or vitreous. The presence of serum antibodies was not necessary for inclusion, allowing to compare the outcomes depending on the serological status.

RESULTS

Seventeen eyes of 15 patients were included. Mean age at diagnosis was 51.9 years. Vitreous inflammation was the most frequent sign (100%). Vitreoretinal tractions (41.2%) and chorioretinal granulomas (58.8%) were less prevalent. Atypical features were: spontaneous intravitreal hemorrhage (23.5%), exudative retinal detachment (11.8%), isolated macular edema (17.6%), papillitis (29.4%) and vasculitis (47.1%). Twenty percent of patients had a positive serum serology. Baseline clinical features did not differ statistically depending on the serological status; however, the degree of inflammation was numerically higher in patients with negative serology. Overall, macular thickness, anterior and posterior segment inflammation improved significantly after treatment with oral albendazole, systemic ± local corticosteroids. Vitrectomy (47.1%) was performed in case of persistent vitritis (62.5%), retinal detachment (12.5%) and intravitreous hemorrhage (25%).

CONCLUSION

OT has no pathognomonic sign and atypical presentations were not infrequent in this adult Caucasian cohort. Serum antibodies were rarely positive, stressing on the importance of ocular sample analysis, especially in case of atypical features. Serum antibodies may prove useful in forecasting the rapidity of inflammation clearance. Antiparasitic and anti-inflammatory treatment was safe and efficient in most cases.