Salmonellosis, 2017

In 2017, 916 Salmonella cases (16.6 per 100,000 population) were reported. This is a 24% increase from the median annual number of cases reported from 2007 to 2016 (median, 739 cases; range, 578 to 975).

Of the 92 serotypes identified in 2017, 5 serotypes, S. Enteritidis (233), S. Typhimurium (97), S. I 4,[5],12:i:- (96), S. Heidelberg (53), and S. Newport accounted for 58% of cases. One large outbreak accounted for 44 of the S. Heidelberg cases. Salmonella was isolated from stool in 820 (90%), urine in 46 (5%), and blood in 41 (4%) cases. Other specimen sources included wound (2), gallbladder (2), genitals, aortic graft tissue, perianal abscess, abdominal abscess, and skin culture of groin.

Two hundred seven (23%) cases were hospitalized; the median length of hospital stay was 4 days (range, 1 to 30 days). Three culture-confirmed cases died; a 94 year-old who died of sepsis and urinary tract infection 1 day after S. Newport was isolated from a urine specimen; a 91 year-old who died of dementia with contributing factors including “gastrointestinal bleed” 3 days after S. Heidelberg was isolated from stool; and a 47 year- old who died of sepsis and probable aspiration pneumonia and Salmonella bacteremia 3 days after S. Enteritidis was isolated from stool.

Of the 831 cases with known travel history, 152 (18%) had travelled internationally during the week prior to their illness onset. There were 7 S. Typhi cases; 1 had traveled to or emigrated from India, 1 to Guatemala, 1 to Kenya, and 4 did not report any travel. There were 2 S. Paratyphi B cases; 1 travelled to Peru, and 1 to Pakistan.

In 2015, culture-independent tests (CIDTs) became commercially available for the detection of Salmonella nucleic acid in stool. In 2017, 43 patient specimens that were positive by a CIDT conducted at a clinical laboratory were not subsequently culture- confirmed, and therefore did not meet the surveillance case definition for inclusion in MDH case count totals.

One hundred twenty-three cases were part of 18 Salmonella outbreaks in 2017, including 3 cases that were part of three national outbreaks with no exposures in Minnesota, and 1 case that was part of an outbreak that began in 2016. Eight of the 14 Minnesota outbreaks involved foodborne transmission, 1 involved animal contact, and 5 were due to person-to-person transmission. Eight of the outbreaks, including the 3 non- Minnesota outbreaks, involved cases in multiple states. The 18 outbreaks resulted in a median of 3 culture- confirmed cases per outbreak (range, 1 to 44). Six culture-confirmed cases and 1 probable case of S. Enteritidis infection were associated with ground beef purchased from a grocery store in Minneapolis. A subset of cases were exposed at a private party where the beef was served raw or medium rare.

Twelve culture-confirmed cases and 1 probable case of S. Enteritidis infection were part of an outbreak at a restaurant. A vehicle was not identified. Transmission occurred over 2 weeks. Multiple Salmonella-positive food workers, and opportunities for cross-contamination were identified. One of the culture-confirmed cases was the result of a subsequent laboratory exposure. Two culture- confirmed cases of S. I 4,5,12:i:- infection were identified who both ate tuna salad at a Minnesota restaurant. No specific ingredient or source of contamination was identified. Over a 5 month period, 44 culture-confirmed cases and 10 probable cases of S. Heidelberg infection were part of an outbreak at two Minnesota locations of a burger chain fast food restaurant with common ownership. Beef patties were associated with illness, but a specific ingredient was not identified. Eight of the confirmed cases were food workers, who may have contributed to transmission.

Over a 7 month period, 3 culture- confirmed S. Newport cases were identified who resided at the same long-term care facility and were likely exposed via person-to-person transmission. Five culture-confirmed cases and 6 probable cases of S. I 4,5,12:i:- infection among residents (and 4 probable cases among staff) who lived in the same unit of a long- term care facility were identified.

The outbreak was likely caused by person-to-person transmission from contaminated hands of staff and/or contaminated environment.

Three culture-confirmed cases of S. I 4,5,12:i:- infection were reported from a child care center; the outbreak was suspected to be caused by person-to-person transmission. Two culture- confirmed case of S. Typhimurium infection were identified who attended the same in-home child care facility.

Three culture-confirmed and 8 probable cases of S. Infantis infection were associated with an outbreak at a child care center.

One culture-confirmed case of S. Livingston infection in a Minnesota resident was part of a restaurant outbreak in Arizona. One Minnesota case of S. Montevideo infection was part of a casino restaurant outbreak in Iowa.

Over a 5 month period, 22 culture- confirmed cases of Salmonella infection (S. Enteritidis, n = 14; S. Typhimurium, n = 4; S. Braenderup, n = 3; S. Indiana, n = 1) were part of a multi-state outbreak linked to live poultry contact. Nationally, 1,120 cases from 48 states in this outbreak were infected with 10 Salmonella serotypes. National tracebacks identified five likely source hatcheries in five states.

One culture-confirmed case of S. Newport infection in Minnesota was part of an outbreak of cases nationally who were exposed to ground beef in Mexico.

Ten culture-confirmed S. Enteritidis cases were part of a multi-state outbreak of 151 cases from 36 states that was associated with romaine lettuce. State and national tracebacks did not identify a single brand, supplier, or growing region.

One culture-confirmed case of S. Kiambu infection and 3 culture- confirmed cases of S. I 6,7:-:1,5 (a monophasic variant of S. Thompson) infection were part of a multi-state outbreak of 220 cases in 23 states. The outbreak was associated with Maradol papayas imported from Mexico. Two culture-confirmed cases of S. Newport infection were part of a multi-state outbreak of 20 cases in 9 states. The suspected vehicle was watermelon; however, a common grower or distributor was not identified. One culture-confirmed case of S. Infantis infection in Minnesota was part of a multi-state outbreak of 48 cases in 14 states; mangoes from Mexico were the suspected vehicle.

• For up to date information see>> Salmonellosis (Salmonella)
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2017