More than 50 people have fallen ill in a national outbreak of Salmonella in Sweden with the source yet to be identified.

A total of 54 confirmed cases of Salmonella Typhimurium have been reported from 20 different regions in the country from Sept. 17 to Oct. 5.

Patients are aged between 8 and 86 years old; 31 of them are women.

Cases have been connected by whole genome sequencing of patient samples. This means they are suspected of having been infected by a common source, according to the Public Health Agency of Sweden (Folkhälsomyndigheten).

Local infection control units, the Swedish Food Agency (Livsmedelsverket) and Folkhälsomyndigheten are investigating the outbreak to identify the source of infection, which is suspected to be a food with wide distribution in Sweden.

Patient interviews to compile information about what those sick have eaten before falling ill are ongoing. Answers will be used to form a hypotheses about the source and compared to what people in a control group that are not part of the outbreak have eaten.

The incident doesn’t appear to be connected to a Salmonella Typhimurium outbreak that is ongoing in Denmark. Officials believe the outbreak in Sweden is caused by a different source because the strains don’t cluster.

In Denmark, 14 cases have been recorded between Aug. 15 and Sept 16. Patients are seven men and seven women aged between 4 and 84 years old, with a median age of 61. 

The Statens Serum Institut (SSI), Danish Veterinary and Food Administration (Fødevarestyrelsen) and DTU Food Institute are investigating to find the source of the outbreak.

about Salmonella
Food contaminated with Salmonella bacteria does not usually look, smell, or taste spoiled. Anyone can become sick with a Salmonella infection. Infants, children, seniors, and people with weakened immune systems are at higher risk of serious illness because their immune systems are fragile, according to the U.S. Centers for Disease Control and Prevention.

Anyone who has developed symptoms of Salmonella food poisoning should seek medical attention. Sick people should tell their doctors about the possible exposure to Salmonella bacteria because special tests are necessary to diagnose salmonellosis. Salmonella infection symptoms can mimic other illnesses, frequently leading to misdiagnosis.

Symptoms of Salmonella infection can include diarrhea, abdominal cramps, and fever within 12 to 72 hours after eating contaminated food. Otherwise, healthy adults are usually sick for four to seven days. In some cases, however, diarrhea may be so severe that patients require hospitalization.

Older adults, children, pregnant women, and people with weakened immune systems, such as cancer patients, are more likely to develop a severe illness and serious, sometimes life-threatening conditions. Some people get infected without getting sick or showing any symptoms. However, they may still spread the infections to others.