Salmonellosis, 2008

During 2008, 755 culture-confirmed cases of Salmonella infection (14.5 per 100,000 population) were reported. This represents a 22% increase from the median annual number of cases reported from 1998 to 2007 (median, 619 cases; range, 576 to 725) (Figure 2) and the highest incidence and number of cases identified in the state since active laboratory surveillance was initiated in 1996. Of the 92 serotypes identified in 2008, five serotypes, S. Enteritidis (167 cases), S. Typhimurium (135 cases), S. Montevideo (52 cases), S. I 4,[5],12:i:- (46 cases), and S. Saintpaul (45 cases) accounted for 59% of cases. Salmonella was isolated from stool in 677 (90%), urine in 27 (4%), and blood in 41 (5%) case-patients. There were 7 cases of S. Typhi infection. Two of the S. Typhi case-patients traveled internationally (India and Indonesia), one was a recent refugee from Thailand, and one was an international student from Nepal. Twenty-five percent of salmonellosis case-patients were 11 years of age or younger. Twenty-eight percent of case-patients were hospitalized for their infection. Of the 666 case-patients who were interviewed, 101 (15%) traveled internationally during the week prior to their illness onset. Eight case-patients died: a 3-year-old case-patient died of hyperleukocytosis (leukemia) 5 days after Salmonella was isolated from a blood specimen; a 70-year-old case-patient died of a pulmonary embolism 5 days after Salmonella was isolated from a stool specimen; a 72-year-old case-patient died of end-stage lung cancer the same day Salmonella was isolated from a stool specimen; a 77-year-old case-patient died of a Clostridium difficile infection 51 days after Salmonella was isolated from a stool specimen; a 78-year-old case-patient died after a diabetic coma 15 days after Salmonella was isolated from a stool specimen; an 85-year-old case-patient died of respiratory failure 20 days after Salmonella was isolated from a stool specimen; an 87-year-old case-patient died of congestive heart failure 9 days after Salmonella was isolated from a blood specimen; and a 90-year-old case-patient died of an upper gastrointestinal bleed/peptic ulcer 18 days after Salmonella was isolated from a urine specimen.

One hundred thirty-nine cases were part of 13 outbreaks of salmonellosis identified in 2008. Nine of the outbreaks involved foodborne transmission, including seven outbreaks with cases in multiple states. Two outbreaks involved contact with animals or food for animals; both had cases in multiple states. Two outbreaks were the result of person-to-person transmission. Nine S. Montevideo cases (6 cases in 2007 and 3 in 2008) with isolates of the same PFGE subtype were part of an outbreak associated with a grocery store deli in Wadena County. The outbreak subtype was the same as that from an earlier outbreak in 2007 associated with contact with chickens. The chicken contact outbreak evidently resulted in infection of deli workers, leading to foodborne transmission to deli patrons. Two deli employees tested positive for the outbreak subtype of S. Montevideo, and one of the employees owned back-yard chickens. Infected foodworkers were most likely the source of contamination; after the two positive employees were restricted from their duties in food service, no additional cases were identified in the area.

As of January, 3 cases (1 in 2007 and 2 in 2008) with the same PFGE subtype of S. Agona were identified and found to have a connection with the same assisted living facility in Anoka County. Based on onset dates collected through case interviews, this outbreak was determined to be the result of person-to-person transmission. The initial source of infection was not identified.

In January, 1 case of S. Agona infection was part of a multi-state outbreak that resulted in 28 cases in 15 states. Puffed rice and puffed wheat cereals of the same brand were implicated as the vehicle. The outbreak subtype of S. Agona was also isolated from a production plant that manufactured the implicated brand of puffed cereals. This investigation resulted in a recall of the implicated product.

Two cases with the same PFGE pattern of S. Hadar were identified from January to April, and both had attended the same daycare facility. The outbreak was determined to be the result of person-to-person transmission.

In February, an outbreak of S. Enteritidis infections was found to be associated with a restaurant in Hennepin County. Eleven culture-confirmed and 4 probable patron-cases were identified. Two restaurant employees tested positive for the outbreak subtype of S. Enteritidis; both denied having a history of gastrointestinal symptoms. One of these employees had begun working at the restaurant shortly before the first reported meal date and had assisted in the preparation of items known to have been consumed by cases. Environmental samples tested negative for Salmonella. In this investigation, one food worker was identified as the ultimate source of contamination.

From March through July, 13 cases with the same PFGE subtype of S. Montevideo were associated with contact with chickens and ducks or their environment. The cases reported purchasing the poultry from a single hatchery in Iowa. The outbreak strain was also isolated from environmental samples taken from two case households. The association of cases infected with this subtype of S. Montevideo and contact with poultry originating from the same hatchery was also seen in 2007.

From February to April, 7 cases of S. Enteritidis with the same PFGE subtype were identified. All cases had consumed the same brand of frozen, pre-browned, single-serving, stuffed chicken product in the week prior to illness onset. Five of the 7 cases cooked the product in the microwave, even though microwave instructions had been removed from the packaging. The same subtype of S. Enteritidis was isolated from a product which one of the cases had purchased at the same time as the products consumed before illness onset, as well as from three retail samples. MDH issued a press release notifying Minnesota consumers about the outbreak, and strongly advising against cooking these types of products in a microwave. In addition, USDA FSIS issued a consumer alert. This was the fifth outbreak of Salmonella infections in Minnesota associated with eating frozen, pre-browned, single-serving, stuffed chicken products.

An outbreak of S. Enteritidis infections associated with contact with snakes was identified in April. Two cases in Minnesota had the same PFGE subtype of S. Enteritidis as 7 cases in five other states that also reported snake contact. It was determined through interviews that feeder mice used by cases in different states originated from a common distributor in Illinois. Subsequent interviews revealed that 5 additional cases from other states with the same subtype of S. Enteritidis that did not have snake contact reported contact with pet mice from the same distributor. Samples collected from these mice tested positive for S. Enteritidis.
An outbreak of S. Saintpaul infections associated with jalapeño peppers served at a restaurant in Ramsey County was identified in June. On June 7, 2008 the U.S. Food and Drug Administration (FDA) issued a national health advisory warning consumers to avoid consumption of Red Round and Roma tomatoes. This advisory followed a case-control study conducted in two states in response to a recent increase in S. Saintpaul infections of a specific PFGE subtype. Following the advisory, multiple cases of the same subtype were identified in Minnesota. Overall, there were 33 cases with the same PFGE pattern identified in the state and over 1,400 cases identified nationwide. Of the 33 total cases in Minnesota, 28 were associated with a single restaurant in Roseville. A case-control study revealed that diced jalapeño peppers were the only ingredient independently associated with illness among restaurant patrons. Following the results of this investigation, the outbreak strain was also found on a pepper and in irrigation water on a farm in Mexico. It is likely that jalapeños, not tomatoes, were responsible for the entire national outbreak.

Another outbreak associated with stuffed chicken products resulted in illnesses starting in June. This time cases were infected with the same PFGE pattern of S. I, 4, 12: i:-. Sixteen cases were identified, and nine reported eating the same brand of stuffed chicken product. The same PFGE subtype of Salmonella was isolated from three products that a case purchased at the same time as products consumed before illness onset, as well as from one retail sample. Additionally, S. Enteritidis, S. Infantis, S. Kentucky and S. Typhimirium were isolated from products. MDH issued a press release notifying Minnesota consumers about the outbreak, and strongly advising against cooking these types of products in the microwave. USDA FSIS issued a consumer alert reminding consumers of the importance of following package instructions and taking the internal temperature of the product with a thermometer.

Six cases of S. Hadar infection with the same PFGE pattern were identified from June to August, and were part of a multi-state outbreak that resulted in 61 cases in 28 states. Illness was associated with consumption of various turkey products, and the outbreak strain was found in product collected from a case household and retail samples. USDA FSIS conducted an inspection of production facilities and provided recommendations on how procedures could be improved to minimize contamination in the future.

A S. Hadar outbreak associated with a family gathering held at a private home in Wisconsin occurred in August. Two culture-confirmed cases and four probable cases were identified. A case-control study was conducted among nine attendees of the family gathering to identify the source of illness. Although no food items were statistically associated with illness, homemade ice cream made with raw, unpasteurized eggs may have been the source. This was the only food item consumed by all ill attendees.

Forty-four cases of S. Typhimurium infection in Minnesota residents with onset of illness from November 2008 to March 2009 were part of a multi-state outbreak associated with consumption of peanut butter and peanut butter-containing products. As of January 2009, isolates of S. Typhimurium of the outbreak subtypes were collected from 529 ill persons in 35 states. In Minnesota, 16 cases were hospitalized and 3 of these died. The outbreak strains of S. Typhimurium were found in both peanut butter and intact packages of peanut butter crackers. The implicated peanut butter and prepackaged peanut butter crackers were recalled, and the production facility is no longer in operation.

• For up to date information see>> Salmonellosis (Salmonella)
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2008