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Surveillance Report

06 June 2017

Gastro-intestinal and Foodborne Infections: Overseas outbreaks of infectious intestinal disease

This report has been generated from the surveillance system that HPS uses to collect and disseminate information on potential outbreaks of infectious intestinal disease believed to have been acquired abroad. A potential outbreak of infectious intestinal disease occurring abroad is defined as two or more confirmed cases of infection or at least one confirmed case where others are alleged to have been ill. Such outbreaks are usually reported to HPS by the NHS board health protection teams. They may also, however, be identified by the reference laboratories. This is particularly the case where phage types or molecular profiles rarely seen in Scotland are involved and/or where the individuals affected are resident in disparate regions of Scotland.

Information on the organism responsible, number positive, number of others suspected to be affected, country, town/resort, hotel or other accommodation, catering (full board/half board/self catering) holiday start and end dates, date of first onset, tour operator, flight details (if applicable) and any other relevant data are disseminated by HPS to the NHS board public health teams in Scotland so that other linked cases can be identified. Where possible, the national surveillance centre in the country where infection is thought to have been acquired is informed directly to enable them to facilitate any investigations or control measures they believe to be necessary. Where HPS does not have direct contacts with the country concerned, information is copied to the Foreign and Commonwealth Office for onward circulation to the relevant country. Where subsequent cases arise in Scotland or where further relevant details emerge after these initial contacts, the relevant national surveillance centres will be updated in order to facilitate local investigations.

In 2016, information was circulated concerning 47 potential outbreaks of infectious intestinal disease in persons returning to Scotland from abroad. This was a decrease compared to the 61 potential overseas outbreaks reported in 2015. Between 2003 and 2016 the average number of potential overseas outbreaks has been 59 per year but with considerable year-on-year variation (Figure 1).

In 2016, Spain (including the Balearic Islands) and Turkey were the two countries generating most frequent reports. In 2016, seven countries were each associated with one potential outbreak.

Salmonella was the most frequently identified pathogen associated with potential overseas outbreaks in 2016 and was reported from 21 (45%) potential outbreaks. While this is in contrast to 2015 when Cryptosporidium was the most frequently reported pathogen, it is consistent with the four years prior to that (2011-2014) when Salmonella was again the most frequently reported. In 2016, Cryptosporidium was reported from 18 potential outbreaks (38%) (Figure 2).

The largest single overseas outbreak reported in 2016 was of Cyclospora among travellers returning from Mexico, with 182 cases reported in Scotland and cases also reported in other parts of the UK. Information for travellers about Cyclospora is available at

To date in 2017, information has been circulated on three potential overseas outbreaks, two of Salmonella and one of E. coli O157. The majority of potential overseas outbreaks are reported during the main summer holiday period.

Verotoxigenic E. coli infection believed to have been acquired outside Scotland.

Due to the potentially serious complications associated with infection with E. coli O157 and other verotoxigenic serogroups of E. coli, HPS operates a similar system to that for outbreaks of infectious intestinal disease for single cases of VTEC infection who report travel outside Scotland in the 14 days prior to the onset of symptoms.

During 2016, HPS disseminated information on six cases of E. coli O157 who had travelled outside Scotland in the 14 days prior to onset of symptoms.

HPS would like to thank all the members of the health protection teams, environmental health officers and microbiologists who contribute to these systems.

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Author(s): Prepared by: GIZ team Vol: 51 No: 22 Year: 2017 Page: