The number of foodborne infections went up in the Netherlands in 2021 but is still below pre-Coronavirus levels, according to a new report.

The Zoonoses Report is published annually by the National Institute for Public Health and the Environment (RIVM) and Netherlands Food and Consumer Product Safety Authority (NVWA). Zoonoses are infectious diseases transmitted from animals to humans and vice versa.

The number of people infected with Salmonella and Campylobacter remained below historic levels. In 2021, measures were again taken to prevent the spread of COVID-19, such as the temporary closure of bars and restaurants, foreign travel restrictions and an increased focus on hand hygiene. The slightly higher incidence compared to 2020 is likely because measures were less strict and for a shorter period of time, found the report.

Campylobacter and Salmonella
It is estimated the number of campylobacteriosis cases in 2021 was 4,219 compared to 3,942 in 2020. More than 90 percent were Campylobacter jejuni, seven percent were Campylobacter coli and the rest were other Campylobacter species. Five foodborne outbreaks with 11 patients were reported, which is a drop from past years.

In 2021, a three-year project on Campylobacter surveillance in the Netherlands began. The aim is to map the clustering of campylobacteriosis cases, and to determine to what extent sources of human clusters can be traced. A total of 57 clusters were detected with a median size of 2 and range of 2 to 14 isolates.

The number of laboratory-confirmed Salmonella infections was estimated to be 1,062 cases compared to 888 in 2020.

As in previous years, the serotypes Enteritidis, Typhimurium and monophasic Typhimurium were the most common causes of salmonellosis. There were 42 clusters of human Salmonella Enteritidis isolates with a median size of 6 but range of 2 to 79 cases. Of the Salmonella Typhimurium isolates, there were 50 clusters with a median size of 3 and range of 3 to 39. Of other Salmonella types, 72 clusters were found with a median size of 2 isolates and a range of 2 to 41.

Six outbreaks affected 159 people. One was the international Salmonella Braenderup outbreak traced to melons from Honduras and another was linked to eggs with 26 cases since 2018. Eleven people were sick in a Salmonella Bovismorbificans outbreak linked to Kosterworst (a dried sausage). The source was not found for two Salmonella Typhimurium clusters with 30 and 32 patients and a Salmonella Montevideo outbreak with 22 patients.

Listeria and E. coli
This past year, 94 Listeria infections were recorded, which is similar to the year before. Eleven people aged 56 to 87 years old died in 2021.

A dozen patients were pregnant at the time of Listeria infection. Two babies were stillborn and one woman had a miscarriage.

The largest cluster consisted of five patients, who fell ill in December, along with nine isolates from previous years and 16 food isolates. There was a microbiological link to a German outbreak with contaminated salmon suspected. Listeria was found several times between 2017 and 2021 at the producer’s factory at low levels. Corrective actions have now been taken.

A total of 483 patients with an STEC infection were reported in 2021, which is up from the year before. Only 33 of 470 patients were thought to have contracted the infection abroad.

Forty percent of E. coli O157 patients were hospitalized compared to 31 percent of non-O157 patients. Two women older than 65 died as a result of E. coli infection. For non-O157, E. coli O26 was the most common, followed at a distance by E. coli O103 and E. coli O63. A total of 29 different O-groups were found.

Hemolytic Uremic Syndrome (HUS) was reported in 25 patients, including 11 children up to the age of 10.

One patient was infected with Brucella melitensis, who may have contracted the infection through consumption of raw camel milk in Ethiopia. This woman was hospitalized as a result of infection.

Pathogens and dairy cattle
Meanwhile, a study at 185 dairy farms found Campylobacter at 91 percent of them.

Every year, RIVM, the NVWA and Wageningen Food Safety Research investigate how often certain pathogens occur in various sectors of livestock farming. In 2021, scientists looked at the manure of cows and calves at Dutch dairy farms and examined whether 107 farmers, family members and employees were carriers of these pathogens. 

Listeria and E. coli was found in manure. Cryptosporidium and Salmonella was detected in young calves and on farms. Campylobacter was found in one person. Two human participants carried Listeria and one carried STEC.

Humans can lower the risk of infection by not consuming raw milk or raw milk products, such as cheese. It is also important to only eat beef that has been thoroughly cooked, said researchers.

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