An increase in Salmonella infections in Sweden has been linked to the consumption of alfalfa sprouts.
Folkhälsomyndigheten (the Swedish Public Health Agency) said 92 people from 18 regions have been infected with one of 12 genetically closely related Salmonella Typhimurium sequence type (ST) 36 variants.
Patients became ill in early August. There are 60 women and 32 men sick. The cases range in age from 1 to 89 years and the median is 44 years old. Most are in the age groups 0 to 10 and 40 to 50 years.
Folkhälsomyndigheten and regional infection control units conducted a case-control study. Questionnaires about food intake in the week before illness were sent to outbreak cases and responses were compared with responses from healthy controls.
Alfalfa sprouts link
The results available so far show that outbreak cases were more likely to have eaten alfalfa sprouts compared to healthy control subjects. These alfalfa sprouts were purchased in different stores or served in different restaurants or canteens.
An investigation is underway involving regional infection control units, municipalities, the Swedish Food Agency (Livsmedelsverket) and Folkhälsomyndigheten.
In September, an outbreak investigation was opened for people infected with a specific variant of Salmonella Typhimurium ST 36. The initial investigation did not determine what caused the illness and the investigation was closed. However, it was restarted and expanded earlier this month after several new variants of sequence type 36 were identified.
Officials have also alerted EU networks to track any possible spread of Salmonella Typhimurium ST 36 in other European countries.
Campylobacter levels have returned to normal
Meanwhile, Swedish officials have declared the Campylobacter outbreak over after a decline in the number of domestically infected cases.
During the second half of July and August, the number of reported cases of Campylobacter infection was the highest, with 150 to 200 cases per week.
A gradual decline followed from mid-August to the end of October, when the number of cases increased again to around 90 per week. The number of reported infections fell to around 50 cases per week at the end of October.
Seasonal variation is observed annually, with an increase in the number of cases in late summer. The increase coincides with the higher occurrence of Campylobacter in broilers. Poor handling of fresh chicken and inadequate cooking are believed to be common causes of infection.
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