Food Outbreak Scan for Jul 15, 2015

News brief

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

News Scan for Jul 15, 2015

News brief

CDC study maps relentless spread of Lyme disease in US

The number of US counties with a high incidence of Lyme disease grew more than threefold over the 20 years from 1993 through 2012 as the illness spread across the Northeast and Upper Midwest, according to a new report in Emerging Infectious Diseases.

Researchers with the Centers for Disease Control and Prevention (CDC) tallied cases of the tick-borne disease reported at the county level over the 20-year period, totaling the cases for four 5-year periods (1993-97, 1998-2002, 2003-07, 2008-12) to minimize the influence of travel-related cases and short-term changes in surveillance practices.

Counties were defined as having a high incidence of Lyme disease if their observed number of cases was more than twice the number of expected cases on the basis of population and time period.

In the first 5-year period, 69 counties were found to have a high Lyme incidence. Except for 4 counties in the Southeast, all were in the Northeast and Upper Midwest. The number of counties increased to 130 in the second 5 years, with the 4 southeastern counties falling off the list, possibly thanks to improved diagnostics. The counties increased to 197 and 260 in the third and fourth periods.

Over the two decades, the number of northeastern counties with a high incidence increased more than 320%, from 43 to 182. The center of the high-incidence area focus in the Northeast generally moved westward and northward, away from the coast of northern New Jersey and into east-central Pennsylvania, the authors found.

In the Upper Midwest—mainly Wisconsin and Minnesota—the number of counties increased about 250% over the 20 years, from 22 to 78. The geographic center of the high-risk region stayed "relatively stable" in northwestern Wisconsin.

"Our results show that geographic expansion of high-risk areas is ongoing, emphasizing the need to identify broadly implementable and effective public health interventions to prevent human Lyme disease," the report concludes. (See CDC map below.)
Jul 15 Emerg Infect Dis report

Study notes 13% rate of drug-resistant Mycoplasma pneumoniae

About 13% of Mycoplasma pneumoniae samples from six US locations tested positive for resistance to macrolides, a group of antibiotics described as the drugs of choice to treat the disease, according to a separate study today in Emerging Infectious Diseases.

US researchers tested 91 respiratory specimens from hospitals in Chicago; New York City; Seattle; Kansas City, Mo.; Hackensack, N.J.; and Birmingham, Ala., using polymerase chain reaction. The samples were collected from August 2012 through April 2014. Patient ages ranged from 10 months to 66 years, but 91% were children.

The team found that 12 specimens (13.2%) were macrolide-resistant. The CDC found a 10% prevalence in samples from 2006 through 2013, the authors report.

The US findings compare with rates from 2% to 26% in Europe and 30% in Israel, the authors say, adding that some areas of China and Japan now have rates exceeding 90%. Macrolide-resistant M pneumoniae was first identified in Asia in 2000.
Jul 15 Emerg Infect Dis study

Flu vaccine patch induced good immune response in small human trial

In a small clinical trial, an influenza vaccine skin patch studded with 200 tiny, soluble needles induced immune responses comparable to those generated by a conventional subcutaneous flu vaccine, Japanese researchers reported in Biomaterials.

Skin patch vaccines have been in development for several years as a possible way to make flu immunization easier and less painful. The authors, from Osaka University, say they developed a dissolving microneedle patch, called MicroHyala, made of hyaluronic acid, a substance that cushions the joints. In previous studies, "transcutaneous" vaccination using the patch induced strong immune responses against various antigens in mice.

In the new study, the team used a patch vaccine containing 15 micrograms of each of three flu antigens (A/H3N2, A/H1N1, and B). They recruited 40 healthy men and randomly assigned them to receive the patch vaccine or a conventional subcutaneous vaccine containing the same amounts of antigens.

The two vaccines generated equal immune responses to the H3N2 and H1N1 antigens, but the patch vaccine triggered a stronger response against influenza B, the report says. Neither group had any severe local or systemic adverse reactions to the vaccines.

In a press release from Elsevier, the journal's publisher, senior author Shinsaku Nakagawa, PhD, asserted that MicroHyala is the only vaccination system of its kind "that is readily adaptable for widespread practical use. Because the new patch is so easy to use, we believe it will be particularly effective in supporting vaccination in developing countries."

The authors said skin patch vaccines made with silicon or metal and soluble polymers have been tested, mainly in animals, but argued that these devices pose a risk of breaking and leaving fragments in the skin.
July 2014 Biomaterials report
Jul 14 Elsevier press release
Related Jul 19, 2010, CIDRAP News story