Researchers have revealed that almost 100 people fell sick in a Salmonella outbreak linked to cantaloupe melon toward the end of 2023.

In September 2023, the UK Health Security Agency (UKHSA) identified cases of Salmonella Saintpaul in England, Scotland, and Wales. Other ill people were noted in Portugal following an alert by the United Kingdom.

Overall, 98 cases were identified, 93 in the UK and five in Portugal, and almost half were under 10, according to the Epidemiology and Infection journal study.

Information on the UK incident was shared via the European Centre for Disease Prevention and Control’s (ECDC) EpiPulse system in late October 2023. This revealed cases in other countries. ECDC confirmed to Food Safety News that two cases had been reported in Denmark.

Young people are mainly affected

Most patients lived in England, but Scotland had ten and Wales five, with sample receipt dates from Sept. 28 to Nov. 30, 2023.

Cases had a median age of 20 from 10 months to 89 years old; 28 percent were under 5, and 43 percent were under 10. Almost two-thirds were female. Five sick people were identified in Portugal, with sample dates from Oct. 4 to 24, 2023. Patients ranged in age from 2 to 8 years old, and 80 percent were female. 

The outbreak investigation included a case-control study. Among the 25 UK cases included in the study, 13 reported blood in stool, and five were hospitalized.

One hundred controls were recruited via a market research panel. Analysis of food exposures in cases and controls identified a strong association with cantaloupe consumption. Melon consumption was reported by 13, or 52 percent of cases, compared with 24, or 24 percent, of controls.

It was not possible to obtain samples of cantaloupe for microbiological testing. Due to factors including the rapid end of the outbreak and the short shelf life of melons, public health control measures such as product recalls were not taken. Food traceback investigations on the source of the produce are ongoing.

In the UK, supply chains for fresh fruit show seasonal variation, which may account for the sharp rise and tail of the outbreak, said scientists.

Clues point to melon as a source

Broader epidemiological investigations provided additional evidence for a link to cantaloupe. All five cases confirmed melon consumption in initial hypothesis-generating interviews, and three reported having cantaloupe.

Of the three educational settings attended by some sick people, they all served melon in the week preceding symptom onset. Two confirmed they had served cantaloupe.

Ten cases also provided details of the supermarket’s loyalty card for the same supermarket. Three reported cantaloupe consumption in targeted questionnaires. Purchasing information for seven cases revealed they had purchased cantaloupe before symptom onset.

“Epidemiological analysis provides evidence for a link with cantaloupe. In light of this and other recent large outbreaks of Salmonella linked to melon consumption, cantaloupe, and other melon varieties should be considered as potential sources of infection during future Salmonella outbreaks,” said researchers.