Denmark reports record low number of outbreaks

By Joseph James Whitworth

- Last updated on GMT

©iStock . Norovirus was the most frequent cause with 16 outbreaks
©iStock . Norovirus was the most frequent cause with 16 outbreaks

Related tags National food institute Foodborne outbreaks Salmonella

Denmark has reported the lowest number of foodborne outbreaks since central tracking began over 10 years ago.

Only 39 foodborne outbreaks were registered in 2015, with 1,233 cases of which 63 were con­firmed in the laboratory.

This includes three Listeria outbreaks from 2014 that had an additional eight cases in 2015.

It is the lowest number since the introduction of the central registration of outbreaks in the Food- and Waterborne Outbreak Database (FUD) in 2005.

The decrease was mainly seen in outbreaks caused by Norovirus, Salmonella and Listeria but there was no single explanation, according to the report.

“Some of the decrease in Listeria outbreaks may be due to the intensive focus and efforts at the production sites investigating presence of Listeria in both products and en­vironment,”​ it added.

The annual report on zoonoses in Denmark in 2015 is from the National Food Institute, Technical University of Denmark, Statens Serum Institut and the Danish Veterinary and Food Administration (for full report open PDF referenced here​).

Highest number of Campylobacter cases ever

The gap between the true number of cases caused by contaminated foods and what is captured by public health surveillance systems can be easily explained, said the report.

“For a case to be identified, the ill person must seek medical care; the doc­tor must request a sample; the causative pathogen must be identified at a laboratory; and the results must be reported to public health officials. Any failure in this process leads to under-diagnosis and under-reporting,”​ it added.

As in previous years Norovirus was the most frequent cause (16 outbreaks) and 530 people were affected.

However, it decreased which may be due to focused campaigns towards restaurants and catering establishments especially during seasonal festive events and holidays, said the report.

Campylobacter continued to be the cause of most registered foodborne infections with 4,348 cases of illness representing a 15% increase from 2014 and is the highest number of cases ever recorded.

A large outbreak caused by a lunch catering company involved 110 people. The source was never identified, but a questionnaire pointed to leafy greens as the probable source.

However, it cannot be concluded whether they were the original source of Campylobacter or the vehicle due to cross con­tamination from other food items in the kitchen.

Historic low for Salmonella

For the first time since the Danish Salmonella source account (1988) no cases were attributed to domestic table eggs and for the fourth time in five years none were attributed to domestic broilers.

There is a zero-tolerance of Salmonella in Danish produced broiler meat.

Birgitte Helwigh, senior scientific officer at the National Food Institute, said the results regarding Danish eggs and poultry are ‘very encouraging’ but Salmonella still constitutes a risk.

“Therefore it is important to maintain the preventive measures that researchers, governments and industry have jointly implemented over the years to ensure that salmonella is kept out of Danish products."

For cases attributed to domestic pork a reduc­tion from 15.4% of cases in 2014 to 3.7% in 2015 was observed. This decrease can partly be ex­plained by the absence of outbreaks related to domestic pork in 2015 for the first time since 2009, said the report.

In contrast to the past three years, where Danish produced pork was the most important food source of human salmonellosis in Denmark, imported pork took the lead in 2015, estimated to account for 6.6% of the total number of cases.

A total of 925 human cases of salmonellosis were reported in 2015, which is the lowest number since the beginning of the 1980s.

Highlights from other pathogens

For each reported human infec­tion of Salmonella, Campylobacter and vero-toxin producing E. coli (VTEC) seven, 12 and 19 people were estimated to be infected and ill, respectively.

This led to an estimate of between 7,800-9,600 cases of salmonellosis, 45,500-52,600 cases of campylobacteriosis, and 2,800-3,900 of VTEC infections annually between 2013-15.

In 2015, 228 episodes of VTEC were registered. VTEC isolates were obtained from 174, of which 33 (19%) were caused by O157 and 19 (11%) by O26 and 17 (10%) by O103.

Clostridium perfringens was associated with 11 foodborne outbreaks affecting 423 people compared to 7, 16, and 8 outbreaks in 2014, 2013 and 2012 respectively.

In September, an increase of Yersinia biotype 4, serotype 3 in Mid Jutland was seen. Interviews revealed an outbreak had occurred after a handball cup with boys and girls 13-14 years. In all, 375 participated and 60 got ill but the source was not identified.

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