In Finland, an average of eight food- and waterborne outbreaks are investigated each month
Municipal outbreak investigation teams notify and investigate suspected food- and waterborne outbreaks in the Finnish Food Authority’s register information system (RYMY). Once the outbreak investigation has been completed, the Finnish Institute for Health and Welfare (THL) and the Finnish Food Authority jointly assess the evidence obtained regarding the causative agent of the outbreak, the vehicle food, and the underlying causes of the outbreak. In recent years, outbreak suspicions have most frequently been reported in December and June.
| Month | Reports |
|---|---|
| 2023 | |
| January | 5 |
| February | 12 |
| March | 11 |
| April | 8 |
| May | 3 |
| June | 9 |
| July | 4 |
| August | 12 |
| September | 5 |
| October | 11 |
| November | 7 |
| December | 10 |
| 2024 | |
| January | 9 |
| February | 11 |
| March | 14 |
| April | 5 |
| May | 6 |
| June | 14 |
| July | 5 |
| August | 2 |
| September | 2 |
| October | 6 |
| November | 4 |
| December | 20 |
| 2025 | |
| January | 7 |
| February | 11 |
| March | 8 |
| April | 4 |
| May | 15 |
| June | 14 |
| July | 5 |
| August | 6 |
| September | 5 |
| October | 7 |
| November | 8 |
| December | 8 |
| 2026 | |
| January | 9 |
| February | 6 |
| March | 9 |
More information on the numbers and causative agents of food- and waterborne outbreaks can be found in the Finnish Food Authority’s Open Data service. The service includes statistics only on outbreaks for which food- or waterborne transmission has been confirmed during the investigation.
Open Data (Finnish Food Authority, in Finnish)
Waterborne outbreaks
During 2023–2026, a total of five outbreaks associated with household water were reported. In 2023, three outbreaks were reported, affecting a total of 152 people. In 2024, two household water–related outbreaks were reported (108 people affected). No household waterborne outbreaks were reported in 2025. The notification procedure for household waterborne outbreaks was introduced in 1997; since then, 110 outbreaks have been reported, with a total of more than 31,000 people affected.
During 2023–2026, a total of six bathing water–related outbreaks were reported. In 2023, four outbreaks were reported (110 people affected). In 2024, two outbreaks were reported in the RYMY system: one related to natural bathing waters and one to pool waters (a total of 11 people affected). No bathing water–related outbreaks were reported in 2025. Notifications of bathing water–related outbreaks have been recorded in the RYMY system since 2012; by 2026, a total of 22 suspected bathing water–related outbreak cases have been registered.
| Household waterborne outbreaks | 2023 | 2024 | 2025 | 2026 |
|---|---|---|---|---|
| Number of outbreaks | 3 | 2 | 0 | 0 |
| Number of people affected | 152 | 108 | 0 | 0 |
| Swimming pool / bathing water outbreaks | 2023 | 2024 | 2025 | 2026 |
|---|---|---|---|---|
| Number of outbreaks | 4 | 2 | 0 | 0 |
| Number of people affected | 110 | 11 | 0 | 0 |
Norovirus is the most common cause of food- and waterborne outbreaks
| Pathogens | % |
|---|---|
| EHEC | 2 |
| Yersinia | 2 |
| Listeria monocytogenes | 2 |
| Clostridium perfringens | 3 |
| Bacillus cereus | 4 |
| Salmonella | 5 |
| Campylobacter | 5 |
| Others | 9 |
| Norovirus | 33 |
| Unknown | 36 |
The causative agent remains unidentified in approximately 36% of outbreaks, most often because patient and/or food samples have not been taken.
Norovirus
Norovirus is the most common cause of food- and waterborne outbreaks. However, it is also frequently transmitted directly from person to person or via contaminated surfaces. Based on the evidence obtained in outbreak investigations, some norovirus outbreaks cannot be classified as food- or waterborne.
National Infectious Diseases Register statistical database – cases, norovirus
Campylobacter
Campylobacter is the most common bacterial cause of gastrointestinal infections in Finland. Campylobacter is usually transmitted through food or water contaminated with human or animal faeces. Transmission from person to person is also possible but not typical.
National Infectious Diseases Register statistical database – cases, Campylobacter
Salmonella
Salmonella is the second most common cause of gastrointestinal infections and the most frequently identified cause of foodborne outbreaks in the European Union. In Finland, Salmonella is the third most common cause of food- and waterborne outbreaks. The outbreaks are often associated with vegetables and plant-based products, with contaminated raw materials acting as the vehicle.
National Infectious Diseases Register statistical database – cases, Salmonella
Listeria monocytogenes
Listeria (Listeria monocytogenes) is a bacterium commonly found in soil and water. Listeria can cause a serious disease in humans, known as listeriosis, through contaminated food.
National Infectious Diseases Register statistical database – cases, listeria
Yersinia
Yersinia bacteria (especially Yersinia enterocolitica and Yersinia pseudotuberculosis) cause gastrointestinal and systemic infections in humans. Yersinia is usually transmitted via contaminated food.
- National Infectious Diseases Register statistical database – cases, Yersinia enterocolitica
- National Infectious Diseases Register statistical database – cases, Yersinia pseudotuberculosis
EHEC
EHEC (enterohaemorrhagic Escherichia coli) is a bacterium transmitted through contaminated food or water. Infection can also occur through direct contact with animals or via hands from another person.
National Infectious Diseases Register statistical database – cases, EHEC
Further information
In addition to the pathogens mentioned above, toxins produced by bacteria (Bacillus cereus, Clostridium perfringens, Staphylococcus aureus, Clostridium botulinum) as well as, more rarely, the protozoan Cryptosporidium and hepatitis A and E viruses, cause food- or waterborne outbreaks in Finland. Depending on the pathogen, the National Infectious Diseases Register statistical database provides weekly or monthly updated data on case numbers. Data can also be viewed by region.
For information on outbreaks caused by food- and waterborne transmission, data are available from the Finnish Food Authority’s Open Data service.
- National Infectious Diseases Register – cases and statistics
- Open Data (Finnish Food Authority, in Finnish)
Reporting services
National Infectious Diseases Register statistical database – cases
Background information
Privacy notice of the National Infectious Diseases Register
Physician’s notification of an infectious disease (in Finnish)
Laboratory notification of an infectious disease (in Finnish)
Sources
The statistics are based on data from the National Infectious Diseases Register and the Finnish Food Authority’s RYMY system.
Description of statistics
THL maintains the national infectious diseases register in accordance with the Communicable Diseases Act and Decree.
Description of the National Infectious Diseases Register
Update schedule
The information on this page will be updated next in autumn 2026.
