FRI BRIEFINGS: Salmonella Human Illness from Food and Non-food Sources 1 FRI BRIEFINGS White Paper on Human Illness Caused by Salmonella from all Food and Non-Food Vectors M. Ellin Doyle1*, Charles Kaspar1, John Archer2, Rachel Klos2 1Food Research Institute, University of Wisconsin–Madison, Madison WI 53706 2Wisconsin Division of Public Health, Bureau of Communicable Diseases, Communicable Disease Epidemiology Section, Madison WI 53702 Contents Introduction....................................................................................................................................2 Epidemiology of Salmonella spp ...................................................................................................2 Outbreaks and cases ...............................................................................................................2 Reservoirs of Salmonellae......................................................................................................3 Farm Animals ................................................................................................................3 Pets ................................................................................................................................4 Wild Animals ................................................................................................................4 Insect Transport Hosts............................................................................................................5 Serotypes................................................................................................................................5 Antibiotic Resistance and Human Illness...............................................................................6 Routes or Vehicles of Human Infection ................................................................................7 Direct Contact ...............................................................................................................7 Contaminated Food .......................................................................................................8 Contaminated Water ....................................................................................................10 Responses to Salmonella Outbreaks.............................................................................................10 Surveillance..........................................................................................................................10 Human Illness ..............................................................................................................10 Animals .......................................................................................................................12 Food .............................................................................................................................13 Regulations ..........................................................................................................................13 Meat .............................................................................................................................14 Fresh Produce...............................................................................................................14 Juice .............................................................................................................................15 Eggs..............................................................................................................................15 Seafood ........................................................................................................................15 Water ...........................................................................................................................15 Animal Feed ................................................................................................................16 Turtles .........................................................................................................................16 Fairs and petting zoos ..................................................................................................16 Industry Initiatives and Interventions ..................................................................................16 Meat ............................................................................................................................16 Eggs .............................................................................................................................17 Fresh Produce ..............................................................................................................18 Summary and Discussion.............................................................................................................18 Serotypes .....................................................................................................................18 Antibiotic Resistance ...................................................................................................18 Vehicles of Infection ...................................................................................................19 February 2009 Update..................................................................................................................19 Figures .....................................................................................................................................20 Tables .....................................................................................................................................25 Reference List ..............................................................................................................................29 Appendix: Chronological List of Salmonella Outbreaks..............................................................44 Corresponding author: M. Ellin Doyle, Ph.D., [email protected] Food Research Institute, UW–Madison, Dec. 2008/February 2009 http://fri.wisc.edu/docs/pdf/FRI_Brief_Salmonella_Human_Illness_6_09.pdf Funded in part by the American Meat Institute Foundation 2 FRI BRIEFINGS: Salmonella Human Illness from Food and Non-food Sources INTRODUCTION Not all animal sources are farm animals even though consumers frequently think of salmonellae as Salmonella spp. have been recognized as human and associated with poultry. Several kinds of meat- animal pathogens for over a century. Numerous sero- producing animals, baby poultry, many pets (particu- types have been described, but seven of these (Enteri- larly reptiles but also cats and other mammals), and tidis; Typhimurium; Newport; I 4,[5],12:i:-; Javiana; wild animals such as hedgehogs have been reported as Heidelberg; Montevideo) were responsible for 61.6% vehicles for salmonellosis. Fecal material from of human cases in the U.S. in 2007. According to infected humans and animals may be transferred recent data from FoodNet, the incidence of salmonel- directly by contact to humans or may contaminate losis has not diminished significantly over the past ten meat during slaughter, fresh produce in the field, years but some serotypes have increased or decreased foods during preparation, and drinking water. in importance (114). Most serotypes are not host- specific, but a few species are restricted to one kind of animal such as S. Pullorum in chickens and S. Typhi (causative agent of typhoid fever) in humans. With the EPIDEMIOLOGY OF SALMONELLAE exception of typhoid and paratyphoid fevers, cases of salmonellosis generally involve mild to moderate Outbreaks and Cases symptoms of gastroenteritis lasting for about five A majority of Salmonella cases are never linked to days. However, the very young, the old, and the outbreaks. In fact, at FoodNet sites in 2007, Salmo- immunocompromised may contract more severe nella isolates from outbreaks comprised only 5.4% of infections (207). Salmonellae may also cause urinary the total Salmonella cases identified; the remaining tract infections and sometimes migrate out of the 94.6% of cases were sporadic with no known connec- intestine and cause septicemia and reactive arthritis tion to other cases (114). CDC estimates that the true (257;401;437;477). incidence of Salmonella infections in the U.S. is about Several large outbreaks of salmonellosis have 38-fold greater than the number of cases actually occurred during the past year. S. Typhimurium present reported. This is because most people experience in municipal tap water affected over 400 people in moderate symptoms and do not seek medical care. Colorado (56) and S. Typhimurium, believed to be Even if a doctor is consulted, clinical samples may not carried in pork, has made more than 1000 people ill in be sent for analysis unless symptoms are severe or a Denmark (175). Perhaps the most noteworthy out- recognized outbreak is in progress. Although most break in 2008 was the nationwide illness caused by reported cases of salmonellosis are sporadic and not S. Saintpaul that extended for several months while specifically related to an identified outbreak, this investigators sought to pinpoint the fresh produce review emphasizes disease outbreaks because there is vehicles of infection (113). more epidemiological information available about Salmonella spp. are estimated to cause about 1.4 potential sources and transmission of salmonellae. million non-typhoidal infections in humans per year in Salmonellosis is typically not fatal, but about the U.S., and it has been estimated that 95%