There were 11 foodborne outbreaks in Scotland this past year with almost 50 people falling ill.

Salmonella and Shiga toxin-producing E. coli (STEC) were the most frequently reported organisms.

Findings come from the Health Protection Scotland (HPS), part of Public Health Scotland (PHS), annual surveillance report on bacterial, protozoal and viral outbreaks of infectious intestinal disease in 2019.

The 11 outbreaks and 49 illnesses in 2019 is down from the 14 outbreaks and 117 illnesses reported in 2018, but in line with the previous five-year average of 13 outbreaks per year. Figures from 2018 include a norovirus outbreak that affected 60 people.

STEC O26 behind largest outbreak
ObSurv is the surveillance system for general outbreaks of Infectious Intestinal Disease (IID) in Scotland. It does not include outbreaks were infection is believed to have been acquired overseas.

In 2019, there were 36 potential outbreaks of infectious intestinal disease in those going back to Scotland from abroad. Turkey was the most frequently country from which people returned with 10 outbreaks. Spain, including the Balearic Islands, was second with nine. Salmonella was the most frequent pathogen linked to overseas outbreaks and was reported from 19 potential incidents.

Four domestic outbreaks of STEC were reported involving three different serogroups; two outbreaks of E.coli O157, one of O26 and one of O125. This was slightly less than the six outbreaks in 2018, and the previous 5-year average of five outbreaks, with a range of three to nine, per year.

E. coli O26 was the largest outbreak with 15 people sick and it was linked to salad leaves. Three people were affected by an E. coli O125 outbreak. An E. coli O157 phage type (PT) 21/28 outbreak had four patients and it was linked to mince. Two people fell ill from E. coli O157 PT31 but the source was not identified.

Salmonella outbreaks part of UK incidents
There were four outbreaks of Salmonella in 2019, involving different serotypes: Java, Mikawasima, Bredeney and Agona. All four were part of United Kingdom-wide outbreaks. This is comparable to the number reported in 2014 to 2018, with an average of five and a range of two to seven outbreaks per year.

Salmonella Mikawasima affected four people, Salmonella Agona sickened three and Salmonella Java just one person. The source was only identified for the Salmonella Bredeney outbreak with two illnesses traced to imported sausage.

Although Campylobacter is the main bacterial cause of infectious intestinal disease, no outbreaks were identified in 2019, highlighting that most cases are sporadic. This is similar to the trend seen in recent years with only one such outbreak reported in the previous five years.

Outbreaks of Listeria are rare in Scotland. In 2019, there was one case, which was part of a larger UK outbreak. The mode of transmission was believed to have been foodborne although the suspect vehicle was not identified.

There was one outbreak of hepatitis A in 2019 with four cases which was multifactorial but not foodborne. There was also one outbreak of Cryptosporidium with 10 cases. Multiple modes of transmission were believed to have been the cause, but not foodborne. There were no outbreaks of norovirus reported in which food was a possible factor.