One person has died in a multi-country Salmonella outbreak linked to salad from Italy.
A foodborne outbreak with about 200 Salmonella Umbilo cases occurred between July and September 2024 in nine European countries. Germany was the most affected with 118 infections.
Salmonella Umbilo was detected in rocket salad (also known as arugula or rucola), and later in baby spinach. According to a study published in the journal Eurosurveillance, both food items came from the same company in Italy.
In mid-August, the Robert Koch Institute (RKI), the national public health agency rocket saladin Germany, observed an unusual increase of clinical Salmonella Umbilo isolates and case notifications. Typing revealed that isolates were genetically closely related. From the end of July to early September, 16 to 21 cases fell ill per week.
In August, Germany alerted other countries about the increase of Salmonella Umbilo cases via EpiPulse, the surveillance portal for infectious diseases of the European Centre for Disease Prevention and Control (ECDC), and, in late September, via the Early Warning Response System (EWRS) of the European Commission.
Major outbreak in several countries
Denmark and Austria also reported Salmonella Umbilo cases in response to Germany’s EpiPulse alert. Up to mid-October, Denmark and Austria had identified 22 and 19 outbreak cases, respectively, and six other European countries reported between one and 20 cases each.
Public health institutes in Germany, Denmark, and Austria collaborated in the outbreak investigation by exchanging information about results from case interviews and other work.
The first reported date of disease onset was July 1 and the latest was Oct. 4. The median age of cases was 37 with a range of 1 to 91 years old. Male and female individuals were equally affected. Of 129 cases with complete information, 36 were hospitalized because of a Salmonella infection and one person was reported to have died due to salmonellosis.
In Germany, 42 cases were interviewed. Of these, 37 consumed leafy green salads in the three days before disease onset, and 24 ate rocket salad.
In Austria, all 18 interviewed cases reported consumption of leafy green salads in the seven days before onset of illness, and 12 mentioned eating rocket salad. Backward tracing along the supply chain of rocket salad served at a café in mid-August revealed it had been distributed by one company and originated from one production region in Italy.
In Denmark, 12 of 14 patients reported having different types of leafy green salads. Eight reported consumption of rocket salad and 10 consumed either rocket salad or baby spinach in the seven days before their illness began.
Traceback work
In Austria, nine samples of rocket salad were collected by authorities from a café and food business mentioned during case interviews. Two different rocket samples distributed by one company from Italy tested positive for Salmonella Umbilo. Sequencing confirmed these isolates belonged to the outbreak cluster.
In Germany, Salmonella was detected in a sample of organic baby spinach collected at the end of August at a supermarket as part of routine monitoring. This was later found to belong to the outbreak cluster and was also distributed by the Italian company.
After being alerted by Austria in September, Italian authorities stopped distribution of rocket salad and all products containing rocket from certain producers in the affected region, and ordered a recall from these producers. It is not yet known how the rocket salad and baby spinach were contaminated.
In Austria, some wholesalers halted all distribution of rocket salad from the implicated company and switched suppliers. By the time positive laboratory results were confirmed, the batch in question was no longer available on the market.
Salmonella Umbilo and other Salmonella serotypes have since been found in additional lots of rocket salad, including a batch from the affected region in Italy, which was sampled in mid-October from a supermarket in Germany. Scientists said the situation requires further attention to ensure that no more cases of salmonellosis occur due to contaminated rocket or other leafy green salads.
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