Submitted to: International Symposium on Epidemiology and Control of Salmonella in Pork
Publication Type: Proceedings
Publication Acceptance Date: 6/18/1999
Publication Date: N/A
Technical Abstract: Salmonella Choleraesuis, the etiologic agent of swine paratyphoid is responsible for more than 90% of swine salmonellosis cases in the United States. Asymptomatic carriers are thought to play a critical role in the spread of this disease through vertical as well as horizontal transmission of this host-adapted pathogen. While this carrier state of swine has been investigated experimentally in weaned pigs, few studies have been done with pigs infected shortly after birth. Presently, we report on the long term fecal shedding, as determined by daily culture of rectal swabs, following experimental infection via oral gavage of 2 day old piglets (n=12) with 2 x 107 colony forming units of a novobiocin and nalidixic acid resistant strain of Salmonella Choleraesuis. Shedding of Salmonella Choleraesuis was most frequent prior to weaning at 14 days of age and for the 7 days immediate post weaning. Contrary to that expected, commingling of piglets previously penned separately and hauling of pigs had little effect on incidence of fecal shedding. At necropsy (85 days post challenge), Salmonella Choleraesuis was recovered from cecal contents of 2 pigs, from spleen and tonsil specimens of 1 and 7 pigs, respectively, but not from colonic contents or either lung or ileocolic lymph node specimens of any of the pigs. Throughout the study, only one pig exhibited respiratory distress and then only after 66 days post challenge. Our results show that Salmonella Choleraesuis can infect neonatal pigs and that these pigs may become long term carriers capable of shedding the pathogen for up to 87 days of age.