In what has become a major international health concern, a widespread Salmonella outbreak has affected nearly 100 individuals across various countries, with the United States now added to the list of affected nations. Since August 2022, authorities have recorded a total of 92 cases of Salmonella Senftenberg, leading to 12 hospitalizations and tragically claiming one life in Germany. The outbreak has raised alarm bells globally due to its rapid spread and cross-border implications.

Of the reported cases, most patients are female, with 28 being male, and infections have been found in all age groups. Germany has borne the brunt of the outbreak, accounting for 26 patients, followed by France with 16 cases, Finland with 12, and Sweden with 11. The United States, while only reporting two cases, is now on high alert for further potential infections.

The initial U.S. case surfaced in October 2022, affecting a 47-year-old female. Subsequently, a 42-year-old male, who had a history of immunocompromisation and had undergone a liver transplant in 2022, fell ill with the disease in April 2023. Health authorities in the United States are closely monitoring the situation to prevent further spread.

The origin of the outbreak has been traced back to a mixed salad that contained cherry tomatoes and green leafy vegetables, prepared in mid-August 2022. However, this particular salad was not ultimately served to airline customers. The contamination likely occurred before the salad reached consumers, raising concerns about the safety of the food supply chain.

The Salmonella Senftenberg strain is relatively uncommon in salmonellosis cases. Over the previous years, the European Centre for Disease Prevention and Control (ECDC) had reported significantly fewer cases - 36 in 2020 and 75 in 2021. The current outbreak, with nearly 100 cases in less than a year, has been far more severe and persistent.

Thirteen countries have reported cases of this outbreak, with Austria, Belgium, the Czech Republic, Estonia, Ireland, the Netherlands, Norway, and the United Kingdom among those affected. The ECDC and the European Food Safety Authority (EFSA) have noted that most cases were reported between October 2022 and March 2023, indicating a concentrated period of infection.

Investigations into the source of the outbreak have pointed to tomatoes as a likely culprit. Interviews with 21 patients from Austria, France, Germany, and Sweden revealed that 20 of them had consumed tomatoes, with 12 also reporting the consumption of iceberg lettuce. National authorities in France and Austria suspected tomatoes as the infection vehicle, tracing the contaminated produce back to wholesalers in Germany, the Netherlands, and Spain, as well as growers in the Netherlands, Spain, and Morocco. However, no conclusive microbiological evidence from tomatoes has been obtained to definitively establish the exact source of contamination.

The intermittent reporting of cases between August 2022 and June 2023 has led experts to believe that contaminated food from a common source has been circulating in the European Union and the UK for about ten months. The fact that linked cases have been identified in the United States suggests either a common source of infection or the possibility of infected individuals traveling to Europe during the outbreak period.

In light of the situation, the ECDC emphasizes the importance of identifying the root cause of microbial contamination in vegetables within the food chain. Such knowledge is critical to ensure appropriate handling and preventive measures are taken by growers, producers, wholesalers, retailers, and consumers, thus mitigating the risk of foodborne illnesses caused by exposure to Salmonella-contaminated vegetables.

Health authorities worldwide are closely monitoring the outbreak and coordinating efforts to contain its spread. The affected countries are implementing strict measures to safeguard public health, and the investigation continues to identify the precise source of the contamination. Consumers are advised to stay informed about official health updates and take necessary precautions to protect themselves from potential infection.