The number of Campylobacter, E. coli, and Salmonella infections all increased in Norway this past year.

Overall, there were more food and waterborne infections in 2019 compared to 2018, according to the Norwegian Institute of Public Health (Folkehelseinstituttet). For information on outbreaks see our previous article.

Campylobacteriosis went past 4,000 cases and, as in previous years, was by far the most common food and waterborne infection. Salmonellosis was slightly higher in 2019 breaking the 1,000 marks but was still below the average for the past 10 years, and continues a downward trend since 2009.

For enterohemorrhagic E. coli (EHEC), the number has gone up in the past 10 to 15 years. Of EHEC cases in 2019, 27 percent and 22 percent were classified as suspected high-virulence and high-virulence, respectively, while 51 percent were classed as low-virulence variants. Reports of other types of E. coli were higher in 2019 compared to 2018.

The 183 cases of tularemia in 2019 were far higher than the 58 in 2018 and exceeded the previous peak year of 2011. There was an increase in parasitic infections giardiasis and cryptosporidiosis compared to the past two years.

Botulism, Brucella, Campylobacter, and cryptosporidium
In 2019, one domestic case of botulism was reported and the suspected source was rakfisk. Four cases of brucellosis were recorded, of which three had been infected abroad and one had an unknown place of infection. Patients were three men and one woman aged 30 to 69 years old.

A total of 4,154 cases of campylobacteriosis were reported compared to 3,669 in 2018. Of these, 1,547 were infected in Norway and 1,873 abroad. In addition, 734 cases had an unknown place of infection.

The predominant type was Campylobacter jejuni with 1,564 cases, but Campylobacter coli at 85 cases and Campylobacter upsaliensis with 12 were also reported. For almost 2,500 cases, the type of Campylobacter was not specified. Of those infected abroad, most were in Spain including the Canary Islands and Mallorca (391 cases), Turkey (170), and Thailand (97). Among those infected in Norway, most were reported in June and August. In total, 545 people were hospitalized.

In 2019, 378 cases of cryptosporidiosis were reported, of which 194 were infected in Norway, 122 abroad, and this was unknown for 62. The total was up from 327 in 2018. After a marked increase in 2016 and 2017, the number has stabilized at about the same level as 2017. The most common countries of infection were Spain, Portugal, and Sweden. Seventy people needed hospital treatment.

E. coli, Giardia and Hepatitis A
Cases of EHEC rose to 511 compared to 494 in 2018 and 406 in 2017. Of the 2019 total, 265 people were infected in Norway, 162 abroad, and for 84 this data was not known. As in previous years, most cases were reported from summer until autumn, mainly in August, July, and September. Most cases were in the age groups 0-9 years (109 cases), 20-29 years (80) and 60-69 years (56).

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EHEC infection led to hospitalization for 112 patients including 22 aged 0-9 years old. Among the 511 cases, 10 developed hemolytic uremic syndrome (HUS), and seven were children aged 0 to 9 years old. Seven HUS cases were infected in Norway, two abroad and this was not known for one person. Three HUS cases were part of an outbreak while two each had O157 and O26.

E. coli O26 was the most common serotype in domestic infections, followed by O157, O63, O128, and O146. O157 was the main type for infections abroad followed by O26, O91, O146, and O63.

In 2019, 578 Giardia cases were reported, of which 264 were infected abroad. The main countries of infection were Uganda for 42 cases, India had 23 and Thailand nine. For 132 cases, no site of infection was specified, and 182 were infected in Norway. The total in 2018 was 465. Of all cases, 81 were hospitalized. Most infections were in age groups 0-9 years, 40-49 years and 30-39 years. In total, 245 cases were women and 333 were men.

Thirty-seven cases of hepatitis A were reported and 27 were hospitalized. Of cases, 10 were infected in Norway, 23 abroad, and for four people the place of infection was not stated. Most were infected in December and September. There were more cases in the age groups 0-9 years, 10-19 years, and 20-29 years. Thirty-two infections were reported in 2018.

Listeria and Salmonella
In 2019, 27 cases of listeriosis were reported, 23 were infected in Norway while four had an unknown place of infection. Most were reported in January, August and June. All cases were hospitalized and two people died. They were mostly in the age groups 70-79 years (13 cases), 80-89 years (seven) and 60-69 years (four).

The number of listeriosis cases was up from 23 in 2018. This can be partly explained by an outbreak that started before Christmas 2018 and continued into 2019. It affected 12 people with seven diagnosed in 2018 and five in 2019. The source was contaminated rakfisk. In Europe, there is also an increasing trend, but the cause of this is unknown.

A total of 1,094 Salmonella cases were reported in 2019. Of these, 318 were infected in Norway, 646 abroad, and for 130 place of infection was not stated. Main countries of infection were Thailand (84 cases), Spain (82) and Turkey (78). Most were reported in August, July and October. Of all reported cases, 314 were hospitalized. Most were reported in the age groups 50-59 years (175 cases), 20-29 years (170) and 60-69 years (155).

The number of patients was slightly higher than 962 in 2018, but still below the average for the last 10 years of 1,013 cases. This represents a continuation of the trend with lower annual numbers seen since 2009. The number of domestic infections has been stable since 2014 and accounted for 29 percent of cases in 2019.

Salmonella Enteritidis was the top serotype in Norway, followed by Agbeni due to an outbreak, Typhimurium, Typhimurium monophasic variant, and Stanley. Enteritidis was also the most common for infections abroad followed by Typhimurium, Typhimurium monophasic variant, Stanley, Java, and Newport.

Vibrio becomes a notifiable disease
In 2019, 133 Shigella cases were reported, of which 36 were infected in Norway, 85 abroad, and for 12 this data was not stated. The most common countries of infection were Egypt and Spain with six cases each and Cape Verde with five. Most were reported in December, September, and November. A total of 30 people were hospitalized. There were most cases in the age groups 30-39 years (24 cases), 20-29 years, and 50-59 years (both 23). The main species were Shigella sonnei (86 cases) and Shigella flexnerii (36). The number of infections was higher than the 102 in 2018.

Forty-nine cases of vibrio infections were reported of which 21 were in Norway, 18 were infected abroad, and for 10 cases no site of infection was stated. Reported cases were largely caused by Vibrio alginolyticus with only a few due to Vibrio parahaemolyticus, Vibrio harveyi or Vibrio fluvialis. Most cases were reported in July and August. Nine people were hospitalized. Cases were 0 to 76 years old with an average age of 36. Vibrio infection was made notifiable in June 2019.

In 2019, 85 cases of yersiniosis were reported, of which 47 were infected in Norway, 22 were infected abroad, and for 16 this was not stated. They were caused by Yersinia enterocolitica, except for one due to Yersinia pseudotuberculosis. Most were reported in December, January, and February. Of all reports, 25 were hospitalized. There were most cases in the age groups 20-29 years (21 cases), 0-9 years (14), and 40-49 years (12).

The number of reported cases was lower compared to 105 in 2018. There were no outbreaks in 2019, but one in early 2020. Although it was notified in January, nine of 11 sick became ill in December 2019. Cases were residents in Eastern Norway. Despite interviews with all of them and the collection of purchase information, the source of infection was not identified.