More than 60 foodborne outbreaks with 1,600 patients were reported in Denmark this past year, according to recently released data.

Three large incidents caused one quarter of the outbreak illnesses. In 2017, 63 outbreaks were reported but only 1,151 people got sick.

Norovirus was the most common cause in 2018 with 21 outbreaks involving 839 cases, a substantial increase compared to 2017 but at the same level as 2016.

The number of people affected by 64 foodborne outbreaks was 1,600 with a median of 12 per outbreak and a range of 2 to 150. Fourteen outbreaks were national, of which two were part of international events. The largest, involving 150 people, was a local outbreak caused by norovirus.

The most frequent setting was restaurants with 20 outbreaks affecting 435 people. Twelve in workplace canteens and through catering also affected a high number with 671 people sick, an average of 56 per outbreak.

Composite meals with 15 outbreaks and buffet meals with nine combined were the top types of foods associated with outbreaks and most often they were caused by norovirus.

Hepatitis A, botulism, Clostridium perfringens investigations
Clostridium perfringens was associated with five outbreaks affecting 107 people compared to eight, seven and 11 outbreaks in 2017, 2016, and 2015.

A large outbreak of hepatitis A infections with 31 sick was linked to dates from Iran. A botulism outbreak involved nine patients caused by a homemade, savory jelly dish. Four became seriously ill requiring intensive care and mechanical ventilation and were hospitalized for up to eight weeks.

Luise Müller, an epidemiologist from Statens Serum Institut, said the figures show Denmark still experiences serious outbreaks that need to be investigated and stopped.

“The successful investigations of the large national outbreak of hepatitis A from Iranian dates and the local botulism outbreak show the importance of Denmark’s interdisciplinary preparedness, which can handle such unforeseen incidents.”

Campylobacter continued to be the most common bacterial foodborne illness in the country, with 4,546 confirmed cases. Two regional outbreaks were reported; one caused by consumption of raw milk with 20 people ill.

Salmonella resulted in 1,168 laboratory confirmed infections, which is a slight increase compared to 1,067 infections in 2017. As in previous years, the two most common serotypes were Salmonella Typhimurium, including monophasic strains, and Salmonella Enteritidis.

Nineteen outbreaks were registered and nine of them related to travel abroad to places such as Egypt, Morocco and Turkey. Six domestic outbreaks were caused by Salmonella Typhimurium or its monophasic variant: O:4,[5],12:i:-. The source was revealed for five outbreaks and four were related to pork meat or pork meat products.

Increase in STEC
The number of registered Shiga toxin-producing E. coli (STEC) cases has increased every year since 2015, and doubled from 2014 to 2018 with 281 cases in 2014 and 495 in 2018. The most common serotype last year was O26, followed by O157 and O103.

A STEC O26:H11 outbreak sickened 39 people and was linked to cured dried beef sausage.

From 2014 to 2018, 55 cases of STEC were associated with Hemolytic Uremic Syndrome (HUS), corresponding to 3.4 percent of all STEC cases. In 2018, 21 cases were registered, which was the highest number ever. Seventy-five percent were reported from June to September.

An outbreak affecting 129 people took place in Jutland at an event for former students at a high school. The causative agent was Enterotoxigenic E. coli O25 (ETEC). An investigation pointed to a common meal at the time of exposure but it was not possible to establish the source or way of transmission.

Lectins in beans caused four outbreaks of which two were large with 50 and 40 illnesses respectively. Dried legumes naturally contain lectins which can cause nausea, vomiting and diarrhea from one to seven hours after consumption.

Two Listeria outbreaks were detected in 2018. Two patients with isolates of Listeria monocytogenes ST20 were linked by WGS to a third isolate from 2016. However, no common link or exposure was identified.

From March to December, four cases of Listeria monocytogenes ST8 were identified and linked by WGS to an additional isolate from 2017. The source was suspected to be different items from a firm producing meat products for catering. A total of 47 cases were reported last year compared to 58 in 2017.

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