Food Outbreak Scan for Jul 15, 2015

Salmonella from raw fish
A decade of E coli O157 data

Minnesota adds two cases to raw fish Salmonella outbreak

Minnesota health officials yesterday linked two recent Salmonella infections to an unusual multistate outbreak tied to raw tuna. The outbreak, first announced by the US Centers for Disease Control and Prevention (CDC) on May 21, involves Salmonella Paratyphi B variant L(+) tartrate(+). As of Jun 5, the CDC had received reports of 53 cases from 9 states.

The two sick Minnesotans are from the Twin Cities area and are in their 30s. Their illness onsets were on Jun 21 and Jun 30, and the Minnesota Department of Health (MDH) said both cases are linked to spicy tuna rolls purchased from a grocery store or a workplace cafeteria.

The MDH added that the outbreak strain was found in sealed bags of raw tuna from the same lot that was used to make the spicy tuna rolls eaten by one of the patients. The contaminated tuna came from Indonesia and was distributed by Osamu Corporation, Gardena, Calif.

The CDC's last update on Jun 5 said state health departments were continuing to test raw tuna products, but the outbreak strain had so far not been detected, so Minnesota's findings appear to be the first to definitively tie the outbreak strain to the tainted tuna.

On May 27 Osamu recalled two lots of its frozen ground yellowfin tuna imported from Indonesia due to possible Salmonella contamination. Tests by Arizona officials had identified Salmonella Newport in one sample and Salmonella Weltevreden in another. The lots recalled by the company are 88569 and 98569. However, the lot linked to the positive finding in Minnesota is from a different one: 68568.

The outbreak strain doesn't cause paratyphoid, enteric, or typhoid fever. It typically causes diarrhea, fever, and abdominal cramps that start 12 to 72 hours after exposure. So far 10 people have been hospitalized, but no deaths have been reported.
Jul 14 MDH news release
Jun 5 CDC outbreak update


Report profiles E coli O157:H7 outbreaks from 2003 to 2012

More Escherichia coli O157:H7 outbreaks were reported in the decade from 2003 through 2012 than in the preceding two decades, probably because of better surveillance, but the share of foodborne outbreaks attributed to beef declined, according to a report today in Emerging Infectious Diseases.

CDC scientists identified 390 E coli O157:H7 outbreaks over the 10 years involving 4,928 illnesses, 1,272 hospitalizations, and 33 deaths. Food led the list of sources, accounting for 255 outbreaks (65%). Others were person-to-person contact (39 outbreaks, 10%), contact with animals (39, 10%), and water (15, 4%), while 42 outbreaks (11%) had a different or unknown mode of transmission.

Although the decade brought more outbreaks than the previous 20 years, they were smaller, with a median of 6 illnesses versus 8, the report says. The hospitalization rate was higher in the later period (27% versus 17%), and the hemolytic uremic syndrome rate was slightly higher (6% versus 4%).

The 65% of outbreaks attributed to food was an increase from 52% in the previous 20 years. Ground beef accounted for 69% of beef-related outbreaks, with steak accounting for 10%. The percentage of all foodborne outbreaks tied to beef was 31%, down from 47% in the earlier period.

The differences between the two time periods "might be partly attributable to continued improvements in surveillance, including the maturation of the national molecular subtyping network, PulseNet, which supported earlier detection of more outbreaks, as well as improved outbreak investigations and systematic, electronic reporting of outbreaks of all transmission modes," the report states.

In other findings, the authors said:

  • Beef and leafy vegetables, taken together, were the source of more than 25% of all reported outbreaks and more than 40% of related illnesses.
  • Outbreaks attributed to foods generally consumed raw caused higher hospitalization rates than those attributed to foods generally consumed cooked (35% versus 28%).
  • The vast majority of waterborne E coli outbreaks (87%) occurred in states along the Mississippi River.

Jul 15 Emerg Infect Dis report

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