No clinical signs or necropsy findings indicating salmonellosis were observed in any of the animals
No clinical signs or necropsy findings indicating salmonellosis were observed in any of the animals. that can later be reactivated, for instance during stress around calving or due to transportation. This study examined nine adult cattle with persistently high antibody responses to S. Dublin O-antigen based lipopolysaccharide for cultivable bacteria in faeces, milk and internal organs before and after transportation, isolation and experimental immunosuppression with dexamethasone sodium phosphate over a period of 7C14 days. Results Clear signs of immunosuppression were seen as expression of leucocytosis and neutrophilia in all animals on day 3C5 after the first injections with dexamethasone sodium phosphate. No clinical signs or necropsy findings indicating salmonellosis were observed in any of the animals. No shedding of S. Dublin was found in faeces (collected four times daily) or milk (collected twice daily) at any point in time during the 7C14 day period. S. Dublin was recovered by a conventional culture method from tissue samples from mammary lymph nodes, spleen and liver collected from three animals at necropsy. Conclusion In this study, immunosuppression by transportation stress or dexamethasone treatment did not lead to excretion of S. Dublin in milk or faeces from infected animals. The study questions the general conception that cattle with persistently Bupropion high antibody levels against S. Dublin O-antigens in naturally infected herds should be considered high risk for transmission and therefore culled as part of effective intervention strategies. It is suggested that the location of S. Dublin infected foci in the animal plays a major role for the risk of excreting bacteria. Background Salmonella enterica subsp. enterica serovar Dublin (S. Dublin) is a zoonotic bacterium which is host adapted to cattle. Although it infects cattle at all ages, severe clinical disease is mostly seen in calves [1]. The bacterium occasionally infects humans where it causes severe illness and high case mortality due to septicaemia [2]. An epidemiologically important feature of S. Dublin is its ability to cause subclinical persistent infection in cattle (carriers) [3]. Such carriers probably harbour the bacterium in cells of the reticular-endothelial system such as the liver and spleen [4] and it is assumed that reactivation of the infection can occur [3,5,6]. It has been hypothesized that reactivation may be caused by stress due to transport or immunosuppression [7-9]. During reactivation animals may shed bacteria and contaminate the environment, thus constituting a source of infection for other animals [10]. Identification of such carriers is assumed to be critical in attempts to control and Bupropion eradicate the infection [11-14]. Bacteriological culture is a common method to diagnose salmonellosis, but due to intermittent shedding of bacteria in milk and faeces by carrier animals, sensitivity of conventional bacteriological culturing is poor in such animals [11,15]. However, serological analyses have indicated that carrier animals elicit a more persistent antibody response to S. Dublin lipopolysaccharide (LPS) than recently infected animals that have eliminated the infection [11,13,16,17]. This has formed the basis for recommendations for control of S. Dublin, i.e. identifying carriers by demonstration of persistently high antibody levels against S. Dublin LPS by ELISA on blood or milk [12,14]. The positive predictive value of the test is, however, questionable, meaning that not all animals detected as carriers based on antibodies are Bupropion truly infected. It has been shown that the bacterium can be isolated at slaughter from around 50% of such persistently seropositive cattle [18]. A low positive predictive value has negative economic implications for the producers, because productive animals may be culled at disadvantageous times. On the other hand, a low negative predictive value would allow for undesired and unknown transmission of infection in the face of a test-and-cull strategy for handling of carrier animals. Effective and cost efficient eradication of S. Dublin infections in cattle requires detailed knowledge about the pathogenesis of prolonged S. Dublin illness, including risk assessment on animals with persistently high antibody titres, and the Bupropion availability of checks with high predictive ideals for large level screenings. The aim of this study was to evaluate if reactivation of a latent illness with S. Dublin happens following transportation and immunosuppression in naturally infected cows with persistently high antibody reactions to S. Dublin O-antigen centered LPS. The study also adds further knowledge to the distribution of S. Dublin bacteria in cells of cows Mouse monoclonal to Caveolin 1 with persistently high antibody reactions. Results and conversation Antibody levels Nine animals from four dairy herds were included in the study. The antibody levels (S. Dublin ODC%) at time of arrival were above 80 for 8 animals, while it was 78 for one cow (No. 2)..