In May 2015 public health officials in Wisconsin investigated an outbreak of Salmonella I 4,[5],12:1:- that occurred among customers of the Supermercado Los Corrales (SLC) located in Kenosha, Wisconsin. Ill persons had purchased food at the store between May 8 and May 11.  The outbreak was detected during a routine interview with a patient diagnosed with Salmonella following a Mother’s Day brunch with extended family members.  Several of the guests were ill with gastrointestinal symptoms.  The family knew of other persons who did not attend their gathering but were also ill.  All ill persons had eaten food prepared at SLC.

Kenosha County Health Department (KCHD) staff worked collaboratively with the Wisconsin Department of Health Services Division of Public Health (DPH) to develop an outbreak specific questionnaire.  Area schools, health care providers and health care facilities were notified that a foodborne outbreak was underway. A “confirmed” case was defined as a person with laboratory confirmation of Salmonella serotype I 4,[5],12:1:- who had exposure to prepared foods from Supermercado Los Corrales during May 8-11, 2015.  A “probable” case was defined as a person who had a diarrheal illness with exposure to prepared foods from Supermercado Los Corrales during May 8-11, 2015.

On May 29, 2015 KCHD and DPH reported 69 outbreak associated cases.  Thirty three were laboratory confirmed with Salmonella serotype I 4,[5],12:1:-. Pulsed field gel electrophoresis (PFGE) analysis showed that patients were infected with one of two closely related genetic strains designated by PulseNet as JPXX01.4356 and JPXX01.4045. There were 33 patients classified as “probable” cases.  There were 3 possible secondary cases.  The first date of purchase was May 7.  Most meals were purchased on May 9 or May 10.  Dates of onset of illness ranged from May 8, 2015 to May 19, 2015.  There were 7 hospitalizations and no deaths.

Kenosha County environmental health specialist, Ryan Lesnjak, conducted the first on-site inspection at SLC on May 14. He interviewed the owner and gathered information about employees and food processes.  None of the food prepared earlier in the week was available for testing.  The next day Mr. Lesnjak and Brad Wozniak interviewed employees and left stool kits which were later collected from three employees. One of the three employees was laboratory confirmed with Salmonella I 4,[5], 12:1:-.

On May 18 the food preparation area and raw meat operations at SLC were closed per order of Kenosha County. Environmental specialists worked with the owner of the SLC and food prep employees to create a “food flow” sheet for carnitas which was the food item implicated as the source of illness.

Based on reports of employee start time and first retail sale of carnitas, investigators doubted there enough time to allow for adequate reheating of the carnitas. This was reported as a proliferation/amplication factor that contributed to the outbreak.

None of the food prepared between May 7-11 was available for testing.  Investigators collected samples of carnitas and salsa prepared on May 18.  Samples were submitted to the Wisconsin Department of Agriculture, Trade and Consumer Protection (WI DATCP) for testing.  None of the samples was positive for Salmonella.  Samples of leftover carnitas collected from two persons who were laboratory confirmed with Salmonella I 4,[45],12:1:- were positive for Salmonella I 4,[5],12:1:- at the WI DATCP laboratory.  The Wisconsin State Laboratory of Hygiene conducted PFGE analysis on these food isolates and determined they were a genetic match to a strain isolated in patients.

On May 22 raw meat operations at SLC were allowed to reopen.  On June 4 no new cases has been reported and the meat preparation area was reopened.

What is Salmonella?

It has long been said that, in 1885, pioneering American veterinary scientist, Daniel E. Salmon, discovered the first strain of Salmonella.  Actually, Theobald Smith, research-assistant to Dr. Salmon, discovered the first strain of Salmonella–Salmonella cholerae suis.  But, being the one in charge, Dr. Salmon got all the credit.  In any case, today the number of known strains of the bacteria totals over two thousand.  In recent years, concerns have been raised, as particular strains of the bacteria have become resistant to traditional antibiotics, in both animals and humans.

The term Salmonella refers to a group or family of bacteria that variously cause illness in humans.  The taxonomy and nomenclature of Salmonella have changed over the years and are still evolving.  Currently, the Centers for Disease Control and Prevention (CDC) recognizes two species which are divided into seven subspecies.  These subspecies are divided into over 50 serogroups based on somatic (O) antigens present.  The most common Salmonella serogroups are A, B, C, D, E, F, and G.  Serogroups are further divided into over 2,500 serotypes, which are typically identified through a series of tests of antigenic formulas listed in a document called the Kauffmann-White Scheme published by the World Health Organization Collaborating Centre for Reference and Research on Salmonella.[1]

Three serotypes – Enteriditis, Typhimurium, and Newport – have persisted as the serotypes most often isolated in patients and reported to the CDC over the last decade.  In 2009,  these three serotypes accounted for 42% of all reported cases of Salmonella.[2]

Where Does Salmonella Come From?

Salmonella is an enteric bacterium, which means that it lives in the intestinal tracts of humans and other animals, including birds.  Salmonella bacteria are usually transmitted to humans by eating foods contaminated with animal feces or foods that have been handled by  infected food service workers who have practiced poor personal hygiene.  Contaminated foods usually look and smell normal and are often of animal origin, such as beef, poultry, milk, or eggs, but all foods, including vegetables, may become contaminated.  Many raw foods of animal origin are frequently contaminated, but thorough cooking kills Salmonella.  But the food handler who neglects to thoroughly wash his or her hands with soap and warm water after using the bathroom may contaminate foods that have otherwise been properly prepared.

What are the Symptoms of Salmonellosis?

Once in the lumen of the small intestine, the bacteria penetrate the epithelium, multiply, and enter the blood within 24 to 72 hours.  Variables such as the health and age of the host and virulence differences among the serotypes affect the nature of the diagnosis.  Infants, the elderly, individuals hospitalized, and the immune-suppressed are the populations that are the most susceptible to disease and suffer the most severe symptoms.

The majority of persons infected with Salmonella have diarrhea, fever, and abdominal cramps within 12-72 hours after exposure.  The illness usually lasts four to seven days, and the majority of persons recover without treatment.  MMWR Weekly, supra at 684.  However, much longer incubation periods of 120 hours to 31 days have been documented in previous Salmonella outbreaks.[3]

The acute symptoms of Salmonella gastroenteritis include the sudden onset of nausea, abdominal cramping, and bloody diarrhea with mucous.  As already noted, there is no real cure for a Salmonella infection; treatment, therefore, tends to be palliative – although prescription of antibiotics is common, even if usually contraindicated.

Medical treatment is acutely important if the patient becomes severely dehydrated or if the infection spreads from the intestines.  Persons with severe diarrhea often require re-hydration, usually with intravenous fluids.  Antibiotics are not necessary or indicated unless the infection spreads from the intestines, and then it can be treated with ampicillin, gentamicin, trimethoprim/sulfamethoxazole, or ciprofloxacin.  Unfortunately, some Salmonella bacteria have become resistant to antibiotics.

Medical Complications

Reactive Arthritis

The term reactive arthritis refers to an inflammation of one or more joints, following an infection localized at a site distant from the affected joints.  The predominant site of the infection is the gastrointestinal tract.  Several bacteria, including Salmonella, induce septic arthritis.[4]  The resulting joint pain and inflammation can resolve completely over time or permanent joint damage can occur.[5]

The reactive arthritis associated with Reiter’s may develop after a person eats food that has been tainted with bacteria.  In a small number of persons, the joint inflammation is accompanied by conjunctivitis (inflammation of the eyes), and uveitis (painful urination).  Id.  This triad of symptoms is called Reiter’s Syndrome.[6]  Reiter’s syndrome, a form of reactive arthritis, is an uncommon but debilitating syndrome caused by gastrointestinal or genitourinary infections.  The most common gastrointestinal bacteria involved are Salmonella, Campylobacter, Yersinia, and Shigella.  Although Reiter’s syndrome is characterized by a triad of arthritis, conjunctivitis, and urethritis, not all three symptoms occur in all affected individuals.[7]

Even though the initial infection may not be recognized, reactive arthritis can still occur.  Reactive arthritis typically involves inflammation of one joint (monoarthritis), or four or fewer joints (oligoarthritis), preferentially affecting those of the lower extremities; the pattern of joint involvement is usually asymmetric.  Inflammation is common at the places where ligaments and tendons attach to bone (enthuses), especially the knee and the ankle.

Salmonella has been the most frequently studied bacteria associated with reactive arthritis.  Overall, studies have found rates of Salmonella-associated reactive arthritis to vary between 6 and 30%.[8]  The frequency of postinfectious Reiter’s syndrome, however, has not been well described.  In a Washington State study, while 29% developed arthritis, only 3% developed the triad of symptoms associated with Reiter’s syndrome.[9]  In addition, individuals of Caucasian descent may be more likely those of Asian descent to develop reactive arthritis,[10] and children may be less susceptible than adults to reactive arthritis following infection with Salmonella.[11]

A clear association has been made between reactive arthritis and a genetic factor called the human leukocyte antigen (HLA) B27 genotype.  HLA is the major histocompatibility complex in humans; these are proteins present on the surface of all body cells that contain a nucleus, and are in especially high concentrations in white blood cells (leukocytes).  It is thought that HLA-B27 may affect the elimination of the infecting bacteria or an individual’s immune response.[12]  HLA-B27 has been shown to be a predisposing factor in one-half to over two-thirds of individuals with reactive arthritis.[13]  While HLA-B27 does not appear to predispose to the initial infection itself, it increases the risk of developing arthritis that is more likely to be severe and prolonged.  This risk may be slightly greater for Salmonella and Yersinia-associated arthritis than with Campylobacter, but more research is required to clarify this.[14]

Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a chronic disorder characterized by alternating bouts of constipation and diarrhea, both of which are generally accompanied by abdominal cramping and pain.[15]  In one recent study, over one-third of IBS sufferers had had IBS for more than ten years, with their symptoms remaining fairly constant over time.[16]  IBS sufferers typically experienced symptoms for an average of 8.1 days per month.[17]

A recently-published study surveyed the extant scientific literature and noted that post-infectious irritable bowel syndrome (PI-IBS) is a common clinical phenomenon first-described over five decades ago.[18]  The Walkerton Health Study further notes that:

Between 5% and 30% of patients who suffer an acute episode of infectious gastroenteritis develop chronic gastrointestinal symptoms despite clearance of the inciting pathogens.[19]

In terms of its own data, the “study confirm[ed] a strong and significant relationship between acute enteric infection and subsequent IBS symptoms.”[20]  The WHS also identified risk-factors for subsequent IBS, including: younger age; female sex; and four features of the acute enteric illness—diarrhea for > 7days, presence of blood in stools, abdominal cramps, and weight loss of at least ten pounds.[21]

As would be expected from a chronic disorder with symptoms of such persistence, IBS sufferers required more time off work, spend more days in bed, and more often cut down on usual activities, when compared with non-IBS sufferers.[22]  And even when able to work, a significant majority (67%), felt less productive at work because of their symptoms.[23]  IBS symptoms also have a significantly deleterious impact on social well-being and daily social activities, such as undertaking a long drive, going to a restaurant, or taking a vacation.[24]  And although a patient’s psychological state may influence the way in which he or she copes with illness and responds to treatment, there is no evidence that supports the theory that psychological disturbances in fact cause IBS or its symptoms.[25]


[1]           Grimont, PAD, Weill, F.  Antigenic formulae of the Salmonella serovars, 2007, 9th Edition.  WHO Collaborating Centre for Reference and Research on Salmonella. Paris: Pasteur Institute.

[2] , Table 1.

[3]           O’ Mahony, et al.  An outbreak of Salmonella Heidelberg infection associated with a long incubation period.  J. Public Health (1990) 12 (1): 19-21;  Abe, et al.  Prolonged Incubation Period of Salmonellosis Associated with Low Bacterial Doses.  J. Food Protection (2004) Vol. 67, No. 12; 2735-2740.

[4]           See J. Lindsey.  “Chronic Sequellae of Foodborne Disease,” Emerging Infectious Diseases, Vol. 3, No. 4,    Oct-Dec, 1997.

[5]           Id.

[6]           IdSee also, Dworkin, et al.  “Reactive Arthritis and Reiter’s Syndrome following an outbreak of gastroenteritis caused by Salmonella enteritidis,” Clin. Infect. Dis., 2001 Oct. 1;33(7): 1010-4; Barth, W. and Segal, K.  “Reactive Arthritis (Reiter’s Syndrome),” American Family Physician, Aug. 1999, online at

[7]           Hill Gaston JS, Lillicrap MS.  (2003).  Arthritis associated with enteric infection.  Best Practices & Research Clinical Rheumatology.  17(2):219-239.

[8]           Id.

[9]           Dworkin MS, Shoemaker PC, Goldoft MJ, Kobayashi JM.  “Reactive arthritis and Reiter’s syndrome following an outbreak of gastroenteritis caused by Salmonella enteritidis.”  Clin. Infect. Dis. 33(7):1010-1014.

[10]          McColl GJ, Diviney MB, Holdsworth RF, McNair PD, Carnie J, Hart W, McCluskey J.  “HLA-B27 expression and reactive arthritis susceptibility in two patient cohorts infected with Salmonella Typhimurium,”  Australian and New Zealand Journal of Medicine.  30(1):28-32 (2001).

[11]          Rudwaleit M, Richter S, Braun J, Sieper J.  “Low incidence of reactive arthritis in children following a Salmonella outbreak,” Annals of the Rheumatic Diseases, 60(11):1055-1057 (2001).

[12]          Hill Gaston and Lillicrap, supra Note 7.

[13]          Id.; Barth WF, Segal K., “Reactive arthritis (Reiter’s syndrome).” American Family Physician, 60(2):499-503, 507 (1999).

[14]          Hill Gaston and Lillicrap, supra Note 7.

[15]          A.P.S. Hungin, et al.  Irritable Bowel Syndrome in the United States: Prevalence, Symptom Patterns and Impact, Aliment Pharmacol. Ther., 2005:21 (11); 1365-75.

[16]          Id. at 1367.

[17]          Id.

[18]          J. Marshall, et al.  Incidence and Epidemiology of Irritable Bowel Syndrome After a Large Waterborne Outbreak of Bacterial Dysentery, Gastro., 2006; 131;445-50 (hereinafter “Walkerton Health Study” or “WHS”).  The WHS followed one of the largest E. coli O157:H7 outbreaks in the history of North America.  Contaminated drinking water caused over 2,300 people to be infected with E. coli O157:H7, resulting in 27 recognized cases of HUS, and 7 deaths.  Id. at 445.  The WHS followed 2,069 eligible study participants.  Id.  For Salmonella specific references, see Smith, J.L., Bayles, D.O., Post-Infectious Irritable Bowel Syndrome: A Long Term Consequence of Bacterial Gastroenteritis.  Journal of Food Protection, 2007:70(7);1762-1769.

[19]          Id. at 445 (citing multiple sources).

[20]          WHS, supra note 34, at 449.

[21]          Id. at 447.

[22]          Id. at 1368.

[23]          Id.

[24]          Id.

[25]          Amy Foxx-Orenstein, DO, FACG, FACP.  IBS—Review and What’s New.  General Medicine, 2006:8(3) (Medscape 2006) (collecting and citing studies).  Indeed, PI-IBS has been found to be characterized by more diarrhea but less psychiatric illness with regard to its pathogenesis.  See Nicholas J. Talley, MD, PhD.  Irritable Bowel Syndrome: From Epidemiology to Treatment, from American College of Gastroenterology 68th Annual Scientific Meeting and Postgraduate Course (Medscape 2003).