More than 4,000 foodborne outbreaks causing almost 22,000 illnesses and 13 deaths were recorded in the Netherlands during a 12-year period.

A total of 4,155 outbreaks, with 21,802 ill people, were registered from 2006 to 2017. The top pathogens were norovirus, Salmonella and Campylobacter.

In 580 outbreaks, with 8,441 sick, a pathogen was found in food, the environment and/or patients. Norovirus, with 172 outbreaks and 3,691 sick was the most commonly reported, followed by Salmonella in 168 outbreaks with 3,125 sick and Campylobacter at 130 outbreaks with 554 sick.

The main pathogens identified in 138 strong evidence outbreaks were Bacillus cereus, Salmonella and norovirus. No pathogen was detected or reported in 86 percent, or 3,575, food-related outbreaks involving 13,361 of those sick.

Most pathogens were found in meats such as beef and chicken, composite products including Asian dishes, and seafood like oysters.

Large 2012 outbreak
The Netherlands Food and Consumer Product Safety Authority (NVWA) and Dutch Municipal Public Health Services (GGDs) register and study food-related infections and poisoning. The National Institute for Public Health and the Environment (RIVM) combines and analyzes the figures.

RIVM said research on food-related outbreaks can provide insight into causes, pathogens, food products, transmission routes and trends.

The number of outbreaks reported through the GGDs is much lower than through NVWA, but with an average of more sick per outbreak.

The average number of patients per outbreak was highest in 2012, caused by one large national outbreak with 1,149 infections due to smoked salmon contaminated with Salmonella Thompson. In second place is 2014 because of several larger outbreaks. Except for 2009 and 2011, there were one to three outbreaks each year with a hundred or more sick.

Hospital admissions were reported for 582 patients out of the 6,418 people for which this data was known. They were highest for Listeria monocytogenes. Thirteen deaths related to a food outbreak were reported: 12 with a Salmonella infection and one with a Campylobacter infection.

Salmonella and Campylobacter outbreaks
A total of 58 food-related outbreaks were caused by Bacillus cereus, Clostridium spp. and/or Staphylococcus aureus with 545 patients. Of eight outbreaks involving multiple pathogens, Bacillus cereus and Clostridium perfringens and Bacillus cereus and Staphylococcus aureus caused two each.

Overall, 170 outbreaks were due to Salmonella with 3,141 patients. There were 91 outbreaks caused by 15 different serotypes, with Salmonella Enteritidis the most common with 51, followed by Salmonella Typhimurium with 23 outbreaks.

Outbreaks linked to the latter are on average larger (33 sick per outbreak) than Salmonella Enteritidis (13 sick per outbreak). Fifteen of the 27 Salmonella outbreaks with a clear link to food were traced to meat, mainly beef, veal, and pork. Four Salmonella Enteritidis outbreaks were due to egg products and two Salmonella Typhimurium outbreaks to milk products.

Overall, 132 outbreaks were caused by Campylobacter with 565 patients. A link with food for 10 outbreaks found they were mainly related to chicken and raw cow, sheep and goat milk.

A total of 173 outbreaks were because of norovirus with 3,700 sick. The main food group responsible is seafood such as oysters with eighteen of the 22 outbreaks that had food links.

Hepatitis A, Listeria, STEC figures
Hepatitis A virus caused eight outbreaks with 79 patients. Two outbreaks were traced to fruit, two to sundried tomatoes and one to mussels. Eleven outbreaks caused by histamine were registered with 75 patients. All cases concerned fish products, mostly tuna but once salmon sashimi.

Nine outbreaks caused by Listeria monocytogenes sickened 31 people. Fish was linked to three outbreaks and chicken to two.

Eleven outbreaks caused by Shiga toxin-producing E. coli (STEC) were registered with 109 patients. STEC O157 was detected in fillet américain in one outbreak and linked to this product in another incident. Pre-packed lettuce and vegetables were behind one outbreak and 11 Dutch patients were part of the huge STEC O104 outbreak from fenugreek sprouts in 2011.

Seven outbreaks were caused by Shigella with 203 patients but a clear link to a food product was not made on any occasion. Vibrio parahaemolyticus from shrimp was behind an outbreak in 2009 and Yersinia enterocolitica caused two outbreaks in 2008 and 2016 but the source was not found.

In food and/or environmental samples, mainly norovirus and Bacillus cereus were found, while in patients Salmonella and Campylobacter were the most common.

All types of meat account for 27 percent of the outbreaks with an identifiable source, with beef, veal and chicken being the main sources. Composite products are in second place with 17 percent and in third are crustaceans and shellfish, mainly oysters and mussels, with 15 percent.

Preparation site was unknown in 104 outbreaks and had a suspected source abroad for 63 incidents. From the other 3,988 outbreaks restaurants and cafes at 63 percent and cafeteria and fast food at 15 percent accounted for more than three-quarters of reports.