Molecular Tools for Monitoring and Source-Tracking Salmonella in Wildlife and the Environment

Salmonella causes an estimated 1.2 million cases of gastroenteritis per year (Scallan et al. 2011) or 16.42 illnesses per 100,000 persons (Gilliss et al. 2013). Salmonellosis is also associated with the largest incidence of food-associated hospitalizations and deaths (Gilliss et al. 2013). Furthermore, no significant change in the incidence of Salmonella infections has occurred since the beginning of surveillance during 1996–1998 (Gould et al. 2013; Gilliss et al. 2013). Many foodborne diseases, including salmonellosis, were once classified as strictly zoonotic infections because they were mostly attributed to meats and products derived from domesticated animals (Chisholm et al. 1999; van Duijkeren et al. 2002). However, recent outbreaks of salmonellosis from produce grown on farms with minimal or no contact with domesticated livestock exemplify the contribution of environmental reservoirs of infections (Gould et al. 2011; Hanning et al. 2009; Danyluk et al. 2007). In fact, the number of illnesses per outbreak is often greater for produce than for any other food product (Franz and van Bruggen 2008). Therefore, wildlife as a source of preharvest contamination of produce with human pathogens is under consideration, including reptiles, amphibians, and birds that may harbor potentially virulent strains of Salmonella (Gorski et al. 2013; Reche et al. 2003; Pfleger et al. 2003).