Toxocaríase: soroprevalência, fatores de risco e avanços no imunodiagnóstico com proteínas quiméricas recombinantes

Abstract

Introduction: Human toxocariasis is among the most neglected helminthic diseases worldwide. Infections by Toxocara spp. are associated with risk factors to which individuals are exposed. Diagnosis of the infection is typically performed through ELISA using excretory-secretory antigens of Toxocara spp. as the gold standard; however, cross-reactivity and variation in precision parameters are some disadvantages of this test. Objective: This study aimed to determine the seroprevalence of toxocariasis in a prospective study (2005-2013); assess the associated risk factors; and produce recombinant chimeric proteins for use in immunodiagnostics. Sera from 926 participants in the SCAALA epidemiological follow-up (2005 and 2013) were immunodiagnosed using indirect ELISA, and associations of the infection with clinical and sociodemographic aspects of the individuals were evaluated. Chimeric proteins (rSHORT and rFULL), based on B-cell epitopes, were expressed and used in the immunodiagnosis of toxocariasis in 232 sera from the Salvador Asthma and Rhinitis Control Program. Results: The prevalence of anti-Toxocara IgG antibodies was 48% in 2005 and 53% in 2013, with 25% of new cases occurring in 2013. Increasing age and exposure to pets were consistent risk factors, while higher maternal education and living on paved streets were protective factors. Positive individuals showed a negative correlation with Skin Prink Test reactivity, while elevated levels of IL-10 and eosinophils in both years were positively associated. The rSHORT protein showed sensitivities of 98.6% and 99.3% in adsorbed and non-adsorbed sera, respectively, while in specificities it reached 94.4% and 97.8%. The rFULL protein showed sensitivities of 93.7% and 89.4%, respectively, and specificities of 86.7% and 81.1%. Conclusion: The infection patterns of Toxocara spp. in our study population were primarily linked to the third age group (≥8 years old) and the presence of cats or dogs at home. Elevating maternal education levels alongside improved housing conditions also emerged as significant factors in mitigating Toxocara spp. infection. Both in Dot Blot and indirect ELISA, the rSHORT protein used as an antigen in the immunodiagnosis of toxocariasis showed superior and more results that are reliable compared to the rFULL protein. Comparatively to TES-26 and CTL-4 molecules, the rSHORT protein demonstrated greater potential to be used as an alternative antigen in the immunodiagnosis of toxocariasis.