On March 23, 2010, the national food surveillance system in Denmark reported a steady occurrence of positive isolates of S. Typhimurium, of unknown phage type and resistant to ampicillin, streptomycin and sulphamethoxazole, in samples from mainly pork meat and products.

Researchers from Denmark and Sweden report in Epidemiology and Infection that several isolates originated from a specific pig slaughterhouse A or a closely associated cutting plant. At this point, although no human cases had yet been identified, an investigation was initiated with the focus on food contamination. On 20 April, a total of 14 human cases with the outbreak type had been confirmed.

A case-control study was undertaken to confirm an association between illness in a subgroup of patients and consumption of teewurst or tea sausage, a spreadable sausage made from fresh salted and smoked pork and beef which is fermented but not heat-treated. The producer of the teewurst had received pork from slaughterhouse A during the period that the outbreak strain had been isolated.

Herds delivering pigs to slaughterhouse A were identified by a unique herd identification number given to all animal herds in Denmark.

From March 2010 and onwards, the outbreak strain was identified in a total of 113 samples; four environmental samples from slaughterhouse A and 109 meat
samples, mainly pork, of which 96 were sampled directly at slaughterhouse A or could be traced back there. Positive meat types included mainly minced pork, pork belly, pork loin and loin back ribs.

Investigation of slaughterhouse A showed positive discovery of the outbreak strain in swabs from equipment and meat samples, even after closing down production for thorough cleaning and disinfection. It was concluded that the establishment was most likely contaminated. Repeated cleaning and disinfection was performed and alterations in equipment and procedures were implemented, From the beginning of July, no further positive samples of the outbreak strain were found at slaughterhouse A.

On 8 July, a press statement was issued jointly by the DVFA and SSI, notifying the public about the salmonellosis outbreak and the link to consumption of pork meat from slaughterhouse A. In addition to describing the outbreak investigation and the action taken to control the outbreak, the statement also contained detailed guidelines on how to prevent infection with Salmonella.

A total of 172 cases of S. Typhimurium U323 were reported between March and September 2010 in Denmark demonstrating how a combination of typing Salmonella isolates from farm-to-fork and from the human population can provide early warning of a salmonellosis outbreak. It also highlights the importance of national Salmonella surveillance which allowed identification of the slaughterhouse contamination and provided the COMG with valuable information to initiate investigative measures. In spite of the existence of these systems, tracing pork meat that has entered the production chain still poses a significant challenge. If feasible, adoption of a standardized automated system across the EU, with detailed product and distribution information, for tracing products might prove worthwhile.

Currently, this is not possible in the EU and such systems are only as good as the data provided by the operators. At present, by the time enough evidence has been gathered to issue a product recall, products with a short shelf-life (such as fresh meat) are most likely to have been consumed.

In this outbreak, early warnings from the Salmonella surveillance system were not sufficient to prevent the outbreak from lasting almost 7 months.

State-of-the-art surveillance, typing, epidemiology and food traceback allowed us to firmly establish the source of the outbreak and, in essence, solve it almost before it became evident; however, legislative measures and some delays in traceback did not allow for sufficient control, resulting in one of the longest lasting Salmonella outbreaks in Denmark.

Foodborne disease outbreaks caused by imported food appeared to rise in 2009 and 2010, and nearly half of the outbreaks implicated foods imported from areas which previously had not been associated with outbreaks, according to research from the U.S. Centers for Disease Control and Prevention, presented today at the International Conference on Emerging Infectious Diseases in Atlanta.

“It's too early to say if the recent numbers represent a trend, but CDC officials are analyzing information from 2011 and will continue to monitor for these outbreaks in the future,” said Hannah Gould, Ph.D., an epidemiologist in CDC’s Division of Foodborne, Waterborne and Environmental Diseases and the lead author.

CDC experts reviewed outbreaks reported to CDC’s Foodborne Disease Outbreak Surveillance System from 2005-2010 for implicated foods that were imported into the United States. During that five-year period, 39 outbreaks and 2,348 illnesses were linked to imported food from 15 countries. Of those outbreaks, nearly half (17) occurred in 2009 and 2010. Overall, fish (17 outbreaks) were the most common source of implicated imported foodborne disease outbreaks, followed by spices (six outbreaks including five from fresh or dried peppers). Nearly 45 percent of the imported foods causing outbreaks came from Asia.

“As our food supply becomes more global, people are eating foods from all over the world, potentially exposing them to germs from all corners of the world, too,” Gould said. “We saw an increased number of outbreaks due to imported foods during recent years, and more types of foods from more countries causing outbreaks.”

According to a report by the Department of Agriculture's Economic Research Service (ERS), U.S. food imports grew from $41 billion in 1998 to $78 billion in 2007. Much of that growth has occurred in fruit and vegetables, seafood and processed food products. The report estimated that as much as 85 percent of the seafood eaten in the United States is imported, and depending on the time of the year, up to 60 percent of fresh produce is imported. ERS also estimated that about 16 percent of all food eaten in the United States is imported. The types of food causing the outbreaks in this analysis aligned closely with the types of food that were most commonly imported.

I sorta cringe, or maybe sigh, every time someone faithfully repeats the dogma that factory-farmed cattle are the source of E. coli O157:H7 and other shiga-toxin producing E. coli (STEC).

All ruminants carry STEC naturally, and there are well-documented and tragic outbreaks involving deer, goats, sheep, elk and others.

German researchers report on the occurrence of STEC in deer in Germany in the current issue of Epidemiology and Infection.

Deer poop has been directly or indirectly linked to several outbreaks:

• 1 dead and 14 sickened from E. coli O157:H7 from deer feces contaminating strawberries in Oregon in Aug. 2011;

• deer feces were a possible source of E. coli O157 in Oregon hazelnuts that sickened 8 in March 2011;

• 29 Minnesota high school students sickened with E. coli O103 and E. coli O145 after butchering and processing deer into venison in 2010;

• deer meat was involved in at least two recognized E. coli outbreaks; and,

• an E. coli O157:H7 outbreak in Oct. 1996 that killed a 16-month-old and sickened 76 others who drank juice which contained unpasteurized apple cider that was probably contaminated with deer feces.

In the current study, the Germans studied the virulence genes eae, e-hlyA and saa, thestx subtypes, pulsed-field gel electrophoresis (PFGE) patterns and serovars. In total, 120 samples of 60 animals were screened by real-time polymerase chain reaction (PCR). The PCR results showed a high detection rate of stx genes (83%). Mainly faecal samples, but also some lymphatic tissue samples, tested stx-positive. All isolates carried stx2, were eae-negative and carried e-hlyA in 38% and saa in 9% of samples. Serovars (O88:[H8], O174:[H8], O146:H28) associated with human diseases were also identified. In some animals, isolates from lymphatic tissue and faecal samples showed undistinguishable PFGE patterns. The examined deer were shown to be relevant reservoirs of STEC with subtype stx2b predominating.

The complete paper is available at http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8501556.

From this week’s Eurosurveillance, Mughini-Gras et al. describe trends in the occurrence of acute infectious gastroenteritis (1992 to 2009) and food-borne disease outbreaks (1996 to 2009) in Italy.

In 2002, the Piedmont region implemented a surveillance system for early detection and control of foodborne disease outbreaks; in 2004, the Lombardy region implemented a system for surveillance of all notifiable human infectious diseases. Both systems are Internet based.

We compared the regional figures with the national mean using official notification data provided by the National Infectious Diseases Notification System (SIMI) and the National Institute of Statistics (ISTAT), in order to provide additional information about the epidemiology of these diseases in Italy. When compared with the national mean, data from the two regional systems showed a significant increase in notification rates of non-typhoid salmonellosis and infectious diarrhea other than non-typhoid salmonellosis, but for foodborne disease outbreaks, the increase was not statistically significant.

Although the two regional systems have different objectives and structures, they showed improved sensitivity regarding notification of cases of acute infectious gastroenteritis and, to a lesser extent, food-borne disease outbreaks, and thus provide a more complete picture of the epidemiology of these diseases in Italy.