**1. Introduction**

Salmonellosis or *Salmonella* infection caused by nontyphoid strains is the most common foodborne disease reported from population-based, active laboratory surveillance in the United States (U.S.) (Figure 1). The overall incidence of laboratory confirmed *Salmonella* 

Fig. 1. Total number of laboratory-confirmed bacterial and parasitic infection cases and hospitalizations by pathogen in the United States (CDC, 2011).

The Burden of Salmonellosis in the United States 3

years lost (QALYs), and \$3.3 billion in total medical expenditures and lost productivity each

*Salmonella* gastroenteritis is usually a self-limited disease in which the symptom of fever typically resolves within 48 to 72 hours and diarrhea within three to seven days. Complications from the infection may include severe dehydration, shock, collapse, and/or septicemia. Symptoms are usually more severe among infants, young children, elderly, and

Although there are many serotypes of *Salmonella* that are pathogenic to both humans and animals (i.e., approximately 2,500 serotypes have been identified), the vast majority of human *Salmonella* isolates are serotype *S. enterica* subsp. *enterica* (Heymann, 2008)*. S*erovars Typhi and Paratyphi of this serotype, *S. enterica* subsp. *enterica,* are the etiologic agents that cause typhoid and paratyphoid fevers. These types are also common, but are generally found in developing countries, such as those in South America, Africa, and parts of Asia (Heymann, 2008). In developed countries where there is active, coordinated foodborne disease surveillance, other

Sixty to eighty percent of all human salmonellosis cases in the United States occur intermittently and sporadically throughout the population. Clusters of large outbreaks in restaurants, institutions for children, hospitals, and nursing homes have occurred recently and remain major public health threats. These outbreaks are usually the product of contamination from a production source, such as chicken farms, feed blending mills, and slaughterhouses. One of the more well-known *Salmonella* outbreaks in the United States occurred in 2010. This outbreak resulted from contamination in the food production chain, leading to a massive egg recall of over half a billion eggs and more than 2,000 reported cases of *Salmonella*-related illness (Hutchison, 2010). Although less common, outbreaks from food handling by an ill person or carrier have been reported in recent years (Cruickshank et al., 1987; Khuri-Bulos et al., 1994). For instance, in 2000 an ill food handler in a bakery that supplied hamburger buns to restaurants was found responsible for an outbreak among several burger restaurants across Southern California and Arizona. This outbreak was atypical in that it resulted from consumption of commercially distributed bread, which is a

highly unusual vehicle for most foodborne infectious agents (Kimura et al., 2005).

for hand washing likely facilitated the transmission to infants (Boehmer, 2009).

**2.2 Salmonellosis incidence – FoodNet data** 

Outbreaks from person-to-person transmission can also be of particular concern, especially among hospital workers who have the potential to spread the bacterium with their hands or through contaminated instruments. Outbreaks of *Salmonella* infection have occurred in places like maternity wards where staff members with contaminated hands and/or the use of contaminated medical instruments result in the transmission of *Salmonella* to babies and mothers (Rowe et al., 1969). In 2008, an outbreak strain of *Salmonella* serotype Tennessee occurred in a neonatal intensive care unit in the United States, where limited access to sinks

Based on FoodNet surveillance data (*see section 4.1*) for nine selected foodborne pathogens from 10 states and three federal agencies (CDC, U.S. Food and Drug Administration, and U.S. Department of Agriculture), a total of 19,089 laboratory-confirmed cases of foodborne infections, 4,247 hospitalizations, and 68 deaths were identified for the year 2010 in the U.S.

year (Batz et al., 2011).

**2.1 Clinical manifestations, serotypes, and outbreaks** 

those who are immune-compromised (Scallan et al., 2011).

serovars such as Typhimurium and Enteritidis are frequently reported.

infection was 17.6 cases per 100,000 persons in 2010. This was more than twice the U.S. Healthy People 2010 objective of 6.8 cases per 100,000 persons (Figure 2) (Matyas et al.,2010). Moreover, a recent report released by the Centers for Disease Control and Prevention (CDC) revealed that the incidence of *Salmonella* infections in 2010 was significantly higher than during 2006-2008 representing an increase of about 10% (95% Confidence Interval (CI), 4- 17%). However, other foodborne infections, such as *Campylobacter*, *Listeria*, *Shigella*, STEC O157, *Vibrio*, and *Yersinia*, have all actually decreased during this same period (CDC, 2011). The disease burden of salmonellosis has remained substantial in the United States in spite of ongoing public health and regulatory efforts to prevent and control this infectious disease.

The present chapter discusses the trends in morbidity, mortality, and years of potential life lost attributed to human salmonellosis in the United States. In addition, this chapter provides a snapshot of U.S. public health measures and control policies that are currently in place to protect the public against *Salmonella* infection.
