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Assessment of serologic response of chickens against Salmonella Gallinarum/Pullorum and S. enteritidis by enzyme-linked immunosorbent assays (ELISA)

Abstract

Avian salmonellosis are diseases caused by bacterial members of genus Salmonella. These bacteria can cause three different infections in birds. S.enterica subspecie enterica serovars Pullorum and Gallinarum are the causative organisms, respetively, of Pullorum disease and fowl thyphoid. Paratyphoid infections are caused by any other salmonela serovars. The epidemiology of the fowl typhoid has been very related with that of the Pullorum disease. Among the decades of 70 and 90, the incidence of the disease in Brazil affected commercial breeders and laying hens, resulting in decrease in egg production and increased mortality. The enzyme linked immunosorbent assay (ELISA) has been used to detect serological responses against Salmonella, although the bacteriologic monitoring is traditionally the main support to detect an infection in the flock. However, researchers demonstrated that nor all the birds showing serologic evidence of infection present fecal excretion of salmonellas, but all the positive birds in bacteriologic exams present antibody titers in ELISA. The industrial aviculture exists in function of its acceptance as food source, then the control strategies have been elaborated in order to avoid the avian salmonellosis and the bird as infection source for humans. Due to liberation of the vaccine against S. Enteritidis for comercial breeders, the traditional rapid slide agglutination test in vaccinated flocks becomes inappropriate. The ELISA using S. Gallinarum as antigen distinguished serologic reactions against serovars Gallinarum/Pullorum and Enteritidis. In that way, the present study aims to investigate the presence of serologic responses in commercial birds against etiological agents of the fowl thyphoid / Pullorum disease as well as S.Enteritidis, to obtain information regarding the occurrence of these infections in commercial flocks and also to analyse the applicability of the test in natural situations. (AU)