The number of Salmonella and Campylobacter infections remained stable this past year according to data from Health Protection Scotland.

During 2019, there were 756 isolates of human non-typhoidal Salmonella reported to Health Protection Scotland (HPS). This was in line with the 751 reports in 2018 but a decrease on the 840 cases in 2017.

Surveillance of Salmonella relies on reports from the Scottish Salmonella, Shigella and Clostridium difficile Reference Laboratory (SSSCDRL) who receive isolates from all diagnostic microbiology labs in Scotland. These are reported to HPS via Electronic Communication of Surveillance in Scotland (ECOSS).

Top serotypes
Most isolates were reported during the summer months. There was another peak later in October which coincides with the mid-term school break.

Salmonella reports in Scotland

The most common serotypes were Salmonella Enteritidis and Salmonella Typhimurium which accounted for 58 percent of all Salmonella isolates in 2019. Salmonella Enteritidis remains the most common with 297 (40 percent of) reports. This was a rise on the 275 in 2018.

Salmonella Typhimurium decreased slightly in 2019, with 135 (18 percent of) reported illnesses compared to 139 in 2018 and 183 in 2017. Salmonella Newport and Salmonella Infantis were the third and fourth most common serotypes with 26 and 23 cases respectively. Forty-three serotypes were recorded only once.

Rates of infection vary across the population with higher ones in children less than 5 years of age compared with older children. Overall rates were slightly higher in females than males.

Almost half of cases, for whom information was available, were believed to have acquired infection abroad.

Campylobacter rates in Scotland

In 2019, there were four outbreaks of Salmonella reported to ObSurv, the surveillance system for all general outbreaks of infectious intestinal disease in Scotland. This compares with six in 2018. All incidents were part of wider United Kingdom outbreaks.

Campylobacter data
During 2019, 5,975 lab reports of Campylobacter were received by HPS. This was a decrease compared with 6,096 reports in 2018 but and an increase on the 5,795 in 2017.

As seen in previous years, most lab reports were recorded in the spring and summer months with a peak in May and June.

The rate of infection was not uniform across the population. Amongst children and young adults, rates were higher in children less than 5 years of age and amongst adults, rates were highest in those aged 50 years and older.

Overall rates were higher in males but the reasons for that are not well understood, according to the report.

Most cases of Campylobacter infection are apparently sporadic. In 2019, no general outbreaks were reported to ObSurv. The last general outbreak reported was in 2014. Since the system was established in 1996 there have been 35 general outbreaks.

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