Norovirus was responsible for the most foodborne outbreaks in Norway this past year, according to a recent report.

The Norwegian Institute of Public Health (Folkehelseinstituttet) found it caused 17 outbreaks while enterohemorrhagic E. coli (EHEC) and Salmonella were both behind four incidents each.

The number of foodborne outbreaks increased to 52 in 2018 from 36 in 2017. A total of 1,109 people reported illness linked to the outbreaks in 2018. The number of cases ranged from two to 148 per outbreak with a median of 13.

Norovirus was also the most common agent in foodborne outbreaks between 2014 and 2016 in Finland.

Outbreaks and people ill
In all the Norway norovirus outbreaks 584 people fell ill, while 23 people were sick in the four EHEC events. Two outbreaks of Salmonella spp. had 11 cases, one of Salmonella Enteritidis included 16 people and five cases were part of a Salmonella Typhimurium outbreak.

Two outbreaks of Yersinia enterocolitica were reported, one of Enterococcus spp led to 57 cases and one due to Listeria monocytogenes included 13 patients.

An outbreak of Campylobacter spp. sickened seven people while cryptosporidium led to six illnesses. For 17 outbreaks with 322 cases the agent of infection was not known.

The strain identified in the Salmonella Enteritidis outbreak had not previously been seen in Norway. based on patient interviews, spices and vegetables were implicated but no certain source was uncovered.

The same outbreak strain was also found in Germany with around 200 cases and one each in Scotland and Luxembourg. An investigation by German authorities indicated egg products or salad could be behind the outbreak.

Two outbreaks with 93 ill were linked to drinks including bottled water but not juice. Products such as shrimp, crustaceans, shellfish and mollusks caused two outbreaks with 18 cases. Vegetables and products thereof including juice caused one outbreak with 28 cases.

The place of infection for most foodborne outbreaks were restaurants, cafes and other eateries. A total of 22 outbreaks with 408 people sick were linked to restaurants, cafes, pubs or bars and fast food outlets.

Eight outbreaks with 233 infections were from hotels and other accommodations, five with 187 cases were from catering businesses and the same number of outbreaks but with 152 people ill were recorded as from private households.

Pathogen trends in Norway
In another report, FHI found the number of food and waterborne infections in 2018 was around the same level as the year before.

Reported cases of campylobacteriosis was lower and salmonellosis was about the same as 2017. Campylobacteriosis fell from 3,883 in 2017 to 3,669 last year and salmonellosis dropped from 992 to 961 last year.

Of the Campylobacter cases, 1,215 were infected in Norway and 1,828 got sick abroad, while this was unknown for 626 cases. Among cases infected in Norway, 362 were hospitalized.

Of the 961 Salmonella cases, 230 were infected in Norway, 587 abroad, and for 144 cases it was not reported. Of all reported cases, 258 were admitted to hospital. Enteritidis was the most common serotype, followed by typhimurium, monophasic S. Typhimurium, Stanley and Newport.

Listeriosis went up to 24 infections from 17 in 2017 and Yersiniosis jumped from 67 to 105 infections.  After several years of increasing parasitic infections giardiasis and cryptosporidiosis, there was a slight decline in 2018.

Twenty three Listeria cases were infected in Norway, while this data was unknown for one person. All of them needed hospital treatment. The increase was mainly due to an outbreak with 13 cases caused by contaminated rakfisk.

For Yersinia, 70 cases were infected in Norway, 18 abroad, and no information was available for 17 people. All reported cases were caused by Yersinia enterocolitica and 29 were admitted to hospital. The increase in 2018 was due to two national outbreaks – one with 20 cases and the other with six.

For EHEC, the number has increased steadily in the last 10 to 15 years and in 2018, 494 cases were reported compared with 406 in 2017 and 239 in 2016.

Of the 494 cases, 268 were infected in Norway, 159 abroad, and information was not known for 67 of them.

Among those infected in Norway, most (24) were in the age groups 0 to 9 years, there were 16 cases in the 70 to 79 years old bracket and 14 infections in the 60 to 69 age group. Infection led to hospitalization for 112 patients, 24 of these in the age group 0 to 9.

Eight children developed hemolytic uremic syndrome (HUS). Three were diagnosed with serogroup O145, three others with O157 and O26 was detected in one child. No deaths were recorded.