The Epidemiology And Public Health Implications Of Salmonellosis In Dairy Cattle
Salmonella enterica is an important zoonotic pathogen that is estimated to cause approximately 94 million illnesses and 155,000 deaths annually throughout the world. Dairy cattle are considered a key source of several Salmonella serovars that cause human disease, and transmission may occur via either foodborne exposure or direct contact with infected cattle. Several previous studies have described the prevalence of fecal Salmonella shedding among asymptomatic dairy cattle, using either cross-sectional or longitudinal designs. However, there is very little in the literature regarding the epidemiology of clinical disease due to Salmonella infection (salmonellosis) in cattle. This dissertation has addressed this gap, both in the field and in a hospital setting, and has emphasized the relevance to public health. The research included herein has shed light on a number of facets of Salmonella epidemiology in dairy cattle, including (1) incidence of salmonellosis in the northeastern United States, along with the serovars and antimicrobial resistance patterns of isolates shed by cattle with clinical illness; (2) prevalence and risk factors for fecal Salmonella shedding among cattle presenting to a teaching hospital; (3) duration of Salmonella shedding following clinical disease in cattle; (4) prevalence of Salmonella shedding among dairy herds with clinical vs. subclinical infections; and (5) emergence of a previously sporadic pathogen (Salmonella Cerro) as a presumptive cause of widespread clinical disease in New York. This work supports the view that dairy cattle with salmonellosis present a greater threat to public health than cattle that are asymptomatically shedding Salmonella organisms; efforts to reduce this threat may thus be facilitated by clinical disease surveillance in dairy cattle populations.
dissertation or thesis