More than 30 people have been confirmed sick in Sweden with Salmonella infections since early October.
The national monophasic Salmonella Typhimurium outbreak has affected 33 people. Whole genome sequencing has shown that patients have the same strain of Salmonella Typhimurium, so are suspected of having been infected by a common source of infection.
Affected local infection control units, the Swedish Food Agency (Livsmedelsverket) and the Public Health Agency of Sweden (Folkhälsomyndigheten) are investigating the outbreak.
The source of infection has not been found but is believed to be a food with a wide distribution in Sweden.
Cases range in age from 2 to 89 years old with a median age of 29. They live in seven different regions of Sweden.
Sixteen people younger than age18 and 13 more older than 60 have been infected. Women make up 21 cases and 12 men are ill.
Monophasic Salmonella Typhimurium was in the top three for the causes of Salmonella patients infected in Sweden in 2020.
Campylobacter levels back to normal
Meanwhile, the number of people getting sick from Campylobacter has returned to normal levels after increasing twice.
A rise in the number of Campylobacter infections was seen from the beginning of July until mid-August when 179 to 191 cases were reported per week.
After one month of gradual decline, the number of reported cases increased again in late September and early October before going back down once more. This pattern was seen across the country.
The spike in human cases was preceded by an increase of Campylobacter in broiler flocks, according to data from the National Veterinary Institute (SVA).
Previous studies have shown that infections are often linked to insufficiently cooked chicken. Officials believe it is likely that the increased presence of Campylobacter in chicken flocks was behind the rise in human cases.
The Public Health Agency of Sweden has collected some samples from cases within the microbiological monitoring program to identify potential common sources of infection. Other work involves comparing the types of Campylobacter detected in patients with those found in chickens.
(To sign up for a free subscription to Food Safety News, click here.)