Outbreak investigations

The National Food Institute, Technical University of Denmark, is part of the national contingency plan for food- and waterborne outbreaks of human disease. Investigations of food and waterborne outbreaks are carried out in close cooperation between the Danish Veterinary and Food Administration, Statens Serum Institut and the National Food Institute.

The National Food Institute has permanent representation on the Central Management Outbreak Group, which coordinates outbreak investigations in Denmark.

Tracing the direct link between patients and the source of infection can be difficult. The cases are often described as sporadic even though they in fact belong to an outbreak.

Tracing tools

In a specific outbreak the number of ill persons is identified by means of different microbiological typing methods (serotyping, antimicrobial resistance typing and DNA typing). The results are used together with information on onset of illness as well as what and where the patients have eaten etc.

Typing results from patients are compared with typing results from food sources, which are very important tools in outbreak investigations.

In most outbreaks it is assumed that only a fraction of the people exposed to illness are reported to the central Food- and waterborne Outbreak Database. There are several reasons for this:

Not everyone exposed becomes ill; only some of the people that become ill go to the doctor; and only some of the patients that go to the doctor have a sample taken for diagnosis

More information on outbreak investigations in Denmark is available at Statens Serum Institut's website.

Suspected Foodborne Outbreaks

A suspicion of an outbreak can occur both centrally and locally:

  • Local suspicion of a foodborne outbreak is reported to the local public health medical officer or the regional veterinary and food authorities, who thereby become aware of a restaurant, a dinner party or the like, which may be the source of illness in several people
  • Central suspicion where Statens Serum Institute observe an increase in the number of cases with a certain type of bacteria. The cases may be confined to a particular geographic area
  • Veterinary suspicion where the National Food Institute or the Danish Veterinary and Food Administration suspect something might be wrong in a herd, a slaughter house or factory.

Suspicion of a food or waterborne outbreak can be reported to the regional veterinary and food authorities under the Danish Veterinary and Food Administration (information in Danish only).


Jette Sejer Kjeldgaard
National Food Institute
+45 35 88 62 69