On-farm risk factors associated with Salmonella in pig herds

In the pig production Salmonella infections are cause of concern for two major reasons. The first is the clinical disease in pigs and the second is that pigs can be infected with a broad range of Salmonella serotypes which can potentially contaminate pork products and pose a threat to human health. In Europe, salmonellosis is the second most frequent zoonoses for number of confirmed human cases and number of hospitalizations. After eggs, the consumption of contaminated pork meat and meat-product is the major cause of human outbreaks. According to the most recent survey conducted on pig farms in the EU in 2008, Italy was among the top five countries with the highest prevalence around 51.2% in breeding farms and 43.9% in production farms. These finding highlighting the need to investigate the risk factors in pig farms that should be managed to maintain a low prevalence. Pigs are susceptible to most Salmonella serotypes and although S. Typhimurium and its monophasic variants are the most common, a large variety of other serotypes are also reported in surveillance studies at farm level. Low Salmonella prevalence in pig herd is associated with a lower contamination pressure at the slaughterhouse reducing the occurrence of cross-contamination of carcasses during the slaughter process and, subsequently, the likelihood that human cases of salmonellosis will occur. This review focuses on risk factors in farms and biosecurity measures that can help to control pig important pathogens at the same time as reducing the within-farm prevalence of Salmonella. The main factors influencing Salmonella infection in pigs can be grouped into four different categories: farm hygiene, feeding practices, herd and health management. However, there is no universal protocol that all pig herds can put into place to minimize the risk of disease introduction or spread. Each farm is unique for host susceptibility, management, facilities, and other influential factors. Biosecurity measures, cleaning and disinfection, feed practices, as well as vaccination are often mentioned as the intervention categories with the greatest potential to reduce Salmonella prevalence in pig farms. The information included in this review may persuade the farmers that improving good hygiene practices and animal management would result in economic rewards. The efforts to control Salmonella in farms could also help to reduce infection by other porcine pathogens.