Eyob Mazengia

Project title: Public Health Impacts of Salmonella from Raw Poultry: Prevalence, Exposure and Epidemiological Links to Cases

Degree: PhD | Program: Environmental and Occupational Hygiene (EOHY) | Project type: Thesis/Dissertation
Completed in: 2013 | Faculty advisor: John Meschke


Infections with Salmonella is a global public health concern. The majority of Salmonella infections are believed to be acquired as results of the consumption of contaminated foods. The ubiquitous nature of Salmonella in the environment, birds, amphibians, reptiles, farm and wild animals, have made source attribution challenging. Salmonella prevalence studies have frequently reported poultry products to have several magnitudes of order higher contamination rates than other animal food products. Therefore, poultry products have been often cited as the major source of salmonellosis in the population and have resulted in numerous efforts to reduce the overall prevalence of Salmonella on raw poultry products through advancement in the industry and governmental initiatives. Despite substantial reduction in the prevalence of Salmonella on poultry products, the incidence of salmonellosis in the population has not declined. The lack of correlation between the prevalence of Salmonella on raw poultry products and that of the incidence of salmonellosis in the population has spurred serious discussion whether or not; there are other major sources of Salmonella, the utility of reducing the prevalence on raw poultry, the responsibility of consumers and whether or not direct links to the incidence of salmonellosis can be made. While there have been numerous prevalence studies conducted over the years, very few have had large sample size, focused on a particular geographical location, sampled over an extended period of time and most importantly were not able to quantify the levels of Salmonella on positive carcasses. Therefore, these studies have not been able to make direct associations between the serotypes and the genetic profiles of those isolates from raw poultry to those of clinical cases reported in the same geographical locations. Therefore, three independent studies were conducted to help bridge the current knowledge gaps. The objectives of the three studies were: Study I) Obtain the prevalence, concentration, antibiotic sensitivities, and the serotypes of Salmonella on raw poultry from retail stores in Seattle, Washington. Study II) Through direct observations, identify the major risk factors leading to cross contaminations during raw poultry handling in domestic kitchens. Study III) Characterize the genetic profiles of the Salmonella isolates recovered from raw poultry and that of cases from the same geographical area.