RESUMEN
The aim of this study was to investigate risk factors for ocular toxoplasmosis (OT) in patients who received medical attention at a public health service. Three hundred and forty-nine consecutive patients, treated in the Outpatient Eye Clinic of Hospital de Base, São José do Rio Preto, São Paulo state, Brazil, were enrolled in this study. After an eye examination, enzyme-linked immunosorbent assay (ELISA) was used to determine anti-Toxoplasma gondii antibodies. The results showed that 25.5% of the patients were seronegative and 74.5% were seropositive for IgG anti-T. gondii antibodies; of these 27.3% had OT and 72.7% had other ocular diseases (OOD). The presence of cats or dogs [odds ratio (OR) 2.22, 95% confidence interval (CI) 1.24-3.98, P = 0.009] and consumption of raw or undercooked meat (OR 1.77, 95% CI 1.05-2.98, P = 0.03) were associated with infection but not with the development of OT. Age (OT 48.2 ± 21.2 years vs. OOD: 69.5 ± 14.7 years, P < 0.0001) and the low level of schooling/literacy (OT vs. OOD: OR 0.414, 95% CI 0.2231-0.7692, P = 0.007) were associated with OT. The presence of dogs and cats as well as eating raw/undercooked meat increases the risk of infection, but is not associated with the development of OT.
Asunto(s)
Toxoplasmosis Ocular/epidemiología , Adulto , Anciano , Anciano de 80 o más Años , Anticuerpos Antiprotozoarios/sangre , Brasil/epidemiología , Distribución de Chi-Cuadrado , Femenino , Humanos , Masculino , Persona de Mediana Edad , Factores de Riesgo , Factores Socioeconómicos , Encuestas y Cuestionarios , Toxoplasma/inmunología , Toxoplasmosis Ocular/inmunologíaRESUMEN
This study analyzed the synthesis of Interferon gamma (IFN-γ), Tumor Necrosis Factor alpha (TNF-α), and Interleukin 10 (IL-10) in chronically infected patients which developed the symptomatic disease as cerebral or ocular toxoplasmosis. Blood from 61 individuals were divided into four groups: Cerebral toxoplasmosis/AIDS patients (CT/AIDS group) (n = 15), ocular toxoplasmosis patients (OT group) (n = 23), chronic toxoplasmosis individuals (CHR group) (n = 13) and healthy individuals (HI group) (n = 10). OT, CHR, and HI groups were human immunodeficiency virus (HIV) seronegative. The diagnosis was made by laboratorial (PCR and ELISA) and clinical subjects. For cytokine determination, peripheral blood mononuclear cells (PBMC) of each patient were isolated and stimulated in vitro with T. gondii antigen. IFN-γ, TNF-α, and IL-10 activities were determined by ELISA. Patients from CT/AIDS and OT groups had low levels of IFN-γ when were compared with those from CHR group. These data suggest the low resistance to develop ocular lesions by the low ability to produce IFN-γ against the parasite. The same patients, which developed ocular or cerebral toxoplasmosis had higher TNF-α levels than CHR individuals. High TNF-α synthesis contribute to the inflammatory response and damage of the choroid and retina in OT patients and in AIDS patients caused a high inflammatory response as the TNF-α synthesis is not affected since monocytes are the major source this cytokine in response to soluble T. gondii antigens. IL-10 levels were almost similar in CT/AIDS and OT patients but low when compared with CHR individuals. The deviation to Th2 immune response including the production of anti-inflammatory cytokines, such as IL-10 may promote the parasite's survival causing the tissue immune destruction. IL-10 production in T. gondii-infected brains may support the persistence of parasites as down-regulating the intracerebral immune response. All these indicate that OT and CT/AIDS patients produced low levels of IL-10 (Th2 response) and IFN-γ (Th1 response). They produced high TNF-α suggesting a high inflammatory response triggered by the parasite.