Illnesses have been reported since September and four people, including three children, have also been affected by hemolytic uremic syndrome (HUS), a condition affecting the kidney.
The cases were connected using whole genome sequencing (WGS) and authorities believe the outbreak to have ended.
Interviews with people who are ill showed a connection to fresh kebab and minced beef skewers with more than five people mentioning these types of products.
Shiga toxin-producing E. coli (STEC) also referred to as Verocytotoxin-producing E. coli (VTEC) or enterohemorrhagic E. coli (EHEC).
EHEC O157 clade 8 is not one of the most common strains but is commonly associated with more severe illness.
Symptoms such as stomach pains and diarrhoea appear typically after two to four days but it can take up to 12 days.
“Ground beef is a product risk since bacteria on the surface can be mixed into the meat when it is ground. Wash hands thoroughly after taking in raw meat and hold separate raw meats and other foods when cooking,” said Mats Lindblad, Livsmedelsverket infection control coordinator.
Livsmedelsverket with Jordbruksverket (Agriculture Department) traced the suspected food throughout the chain back to the farm level.
Analyses from the Folkhälsomyndigheten (Public Health Agency) and the Statens veterinärmedicinska anstalt (SVA) found it was the same variant of O157 in sick people as at the farm during sampling.
Based on the findings of the sampled farms livestock owners have received hygiene advice, guidelines and recommendations from Jordbruksverket on measures to get rid of the infection.
Mitigation measures include repeated sampling and the slaughter process being slowed down.
Infection can be spread through contact with animals or manure but also through contaminated food, water or the environment around the infected animals.
The relevant county council infectious disease units, NFA, National Veterinary Institute, Agriculture and the Public Health Agency worked together to investigate the outbreak.
NRLs for E. coli
The 11th annual workshop of the National Reference Laboratories (NRLs) for E. coli in the EU was held in Rome last week.
Karin Johansson, of the European Centre for Disease Prevention and Control (ECDC), gave an update on the Epidemic Intelligence Information System for Food- and Water-borne diseases (EPIS-FWD).
The use of NGS for characterization and typing of pathogenic E. coliand metagenomics to study STEC infections was presented by speakers from the Istituto Superiore di Sanità which hosts the European Union Reference Laboratory for E. coli (EURL-VTEC).
A STEC and EPEC foodborne outbreak in Finland linked to rucola (a type of salad) from Denmark via Sweden in August and the Romanian O26 VTEC outbreak were also discussed.