Frequency of anti-Toxoplasma gondii serology, ocular lesions and associated risk factors in Cássia dos Coqueiros, Brazil.

Abstract

Purpose : To describe the frequency of anti-Toxoplasma gondii positive serology, the frequency of presumed ocular toxoplasmosis (OT), and associated risk factors in Cassia dos Coqueiros, Brazil.

Methods : All adults resident in Cássia dos Coqueiros (Southeast Brazil, with an estimated population of 2,591 inhabitants), were invited to participate in the study. Participants were submitted to peripheral blood collection for the detection of IgG and IgM against T. gondii by a chemiluminescent microparticle immunoassay. They were also submitted to ocular examination (indirect ophthalmoscopy and presenting visual acuity testing) and responded a questionnaire to investigate toxoplasmosis-related risk factors. Masked uveitis specialists made the diagnosis of presumed OT by the presence of either focal retinitis or hyperpigmented retinochoroidal scars. Lesions suggestive of OT were documented and then analyzed by three masked and experienced examiners. Lesions considered “presumed toxoplasmosis” by at least two examiners were considered OT in this study, and multivariate analysis was performed.

Results : We included 990 subjects (40% men and 60% women). Frequency of T. gondii IgG+ IgM- and IgG+ IgM+ was 63.0% (n=625) and 2.5% (n=25), respectively. Female sex, older age, lower educational levels, presence of felines at home, consumption of undercooked meat, and previous diagnosis of toxoplasmosis were independently correlated with positive serology. Seven hundred twenty-one individuals were submitted to an eye exam, 490 of those with IgG+ IgM- and 19 IgG+ IgM+ serology. OT was found in 51 subjects (7.0% of those examined). Most individuals presented unilateral (n= 45, 88%), peripheral only (n= 45, 88%) and single lesions (n=37, 65%). Lower socioeconomic status (odds ratio 2.53, p= 0.019) was associated with OT. No differences in the mean visual acuity was found between those with or without OT.

Conclusions : A high percentage of individuals presented IgG+ IgM- serology (63%), indicating past exposure to T. gondii. Preventing practices should target those at a higher risk of exposure, like individuals with lower socioeconomic status. Despite the high frequency of OT in this population (7.0%), the presence of OT was not associated with reduced visual acuity, potentially because most lesions found were peripheral.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.