RESUMEN
Toxoplasmosis and neosporosis have been recognized as economically important diseases with considerable impact on the livestock industry. Considering the scarce information on the occurrence of Toxoplasma gondii and Neospora caninum infections in sheep from Uberlândia, Minas Gerais State, Brazil, this study aimed to investigate the frequency of antibodies against these parasites in sheep sera from this region by using different serological methods. A total of 155 sheep serum samples were analyzed by the indirect fluorescence antibody test (IFAT) and enzyme-linked immunosorbent assay (ELISA) for the detection of IgG against T. gondii and N. caninum. Seroreactivity by IFAT showed 80% of samples with titers between 512 and 2048 for T. gondii (cutoff ≥ 64) and 78% presenting titers between 50 and 200 for N. caninum (cutoff ≥ 50). Seroreactivity by ELISA showed 75% of samples with ELISA index (EI) between 2.0 and 3.0 for T. gondii (cutoff ≥ 1.3) and 54% presenting EI between 1.3 and 2.0 for N. caninum (cut off ≥ 1.3). Discordant results by both tests were analyzed by immunoblot, resulting in a total seropositivity of 61% for T. gondii and 23% for N. caninum, with 41% to T. gondii only, 3% to N. caninum only, and 20% to both parasites. There was a significant positive association between seropositivity to T. gondii and age over one year (P<0.001), but such association was not found for N. caninum infection. In conclusion, as T. gondii and N. caninum infections are simultaneously present in sheep flocks of this region, it should be emphasized the importance to carry out a regular monitoring of Toxoplasma infection due to its high prevalence, its zoonotic potential and induction of reproductive disorders leading to economic losses. For neosporosis, sheep farmers should be instructed about the presence of the parasite in the flock, its risk factors and potential abortifacient role in sheep. Differential flock management could be valuable tool to establish the association of serological positivity and reproductive disease induced by N. caninum in sheep.
Asunto(s)
Coccidiosis/veterinaria , Neospora/inmunología , Enfermedades de las Ovejas/epidemiología , Toxoplasma/inmunología , Toxoplasmosis Animal/epidemiología , Factores de Edad , Animales , Anticuerpos Antiprotozoarios/sangre , Brasil/epidemiología , Coccidiosis/epidemiología , Coccidiosis/inmunología , Coccidiosis/parasitología , Ensayo de Inmunoadsorción Enzimática/veterinaria , Femenino , Técnica del Anticuerpo Fluorescente Indirecta/veterinaria , Immunoblotting/veterinaria , Inmunoglobulina G/sangre , Masculino , Ratones , Neospora/patogenicidad , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Estudios Seroepidemiológicos , Ovinos , Enfermedades de las Ovejas/inmunología , Enfermedades de las Ovejas/parasitología , Oveja Doméstica , Toxoplasma/patogenicidad , Toxoplasmosis Animal/inmunología , Toxoplasmosis Animal/parasitologíaRESUMEN
This study aimed to determine the pre-patent period and to evaluate the kinetics of cyst elimination and the systemic humoral (IgA, IgG(1), IgG(2a), IgM, IgE) and intestinal secretory (IgA) immune responses in gerbils (Meriones unguiculatus) experimentally innoculated with different doses of Giardia duodenalis trophozoites. Forty-eight animals aged 6-8 weeks were used, equally distributed among six groups, five groups innoculated with different doses of trophozoites (10(1), 10(2), 10(3), 10(4), 10(5)) and one control (non-infected) group. Coproparasitological examinations were carried out daily up to 91 days after inoculation (d.a.i.) to determine the pre-patent period and the kinetics of cyst elimination. Blood and stool samples were weekly collected for antibody assays. The pre-patent period was observed from the 9 d.a.i. onwards, with intermittent elimination of variable quantities of cysts up to 27 d.a.i.. All infected gerbils, irrespective of the dose received, were able to mount systemic humoral immune responses as evidenced by specific IgM titers from 7 to 28 d.a.i., corresponding to the peak of cyst elimination, followed by high and persistent IgG1 titers. Intestinal secretory responses were also seen with two peaks of fecal IgA titers, corresponding to IgM and IgG1 response peaks, respectively. In conclusion, systemic and intestinal humoral immune responses were related to the control of giardiasis in this experimental model.