Salmonella Surveillance Systems in Swine and Humans in Spain: A Review

Abstract

Non-typhoid salmonellosis is a common and problematic foodborne zoonotic disease in which pork and pork products can be an important potential source of infection. To prevent this disease, important efforts to monitor the situation in the main source, livestock, are conducted in most developed countries. In the European Union, European Food Safety Agency (EFSA) and European Center for Disease Control (ECDC) compile information at the member-state level, even though important differences in production systems and surveillance systems exist. Here, Salmonella surveillance systems in one of the main sources of foodborne salmonellosis, swine, and humans in Spain were reviewed to identify potential gaps and discuss potential ways of integration under a "One-Health" approach. Despite the extensive information generated through the surveillance activities, source attribution can be only routinely performed through ad-hoc outbreak investigations, and national reports on human outbreaks do not provide sufficiently detailed information to gain a better understanding of the epidemiology of the pathogen. Human and animal monitoring of Salmonella would benefit from a better exchange of information and collaboration. Analysis of spatio-temporal trends in livestock and humans could help to identify likely sources of infection and to target surveillance efforts in areas with higher prevalence or where specific strains are found.

Keywords: disease control; domestic livestock; foodborne; one health; pig; public health; zoonoses.

Figure 1

Number and distribution of slaughterhouses sampled and results of the Salmonella annual monitoring program in slaughter pigs in Spain. In black, number of total holdings and slaughterhouses (SH) sampled (time period of sampling). In red, positive (+) results to Salmonella. (Self-creation from the information retrieved from the reports in MAPA website).

Figure 2

Distribution by serotype of the proportion of positive holdings to Salmonella (of total holdings tested per year) in slaughter pigs per year. This information is based on the annual Spain country reports (2008–2012).

Figure 3

Salmonella surveillance “from farm to fork” (from pig source). AECOSAN notifies MAPA of the detection of meat contaminated with Salmonella, so that corrective action can be taken (indicated with a dotted line in Figure 1). In addition, the two surveys carried out by EFSA request are indicated, the results of which are kept by MAPA. AMR = antimicrobial resistance.

Figure 4

Salmonella surveillance in suspect patients in Spain (from ingestion of contaminated product or other exposure route). It summarizes the surveillance of Salmonella in humans, which starts with the onset of clinical signs in a suspect patient.