This report presents information on 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 information is disseminated by HPS to the NHS board public health teams in Scotland, so that other linked cases can be identified. Where possible information is also sent directly to the national surveillance centre in the country where infection is thought to have been acquired, enabling 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. After the initial information has been disseminated, if additional cases are identified in Scotland or additional information becomes available, this information is passed to the relevant national surveillance centre in order to facilitate local investigations.
In 2015, information was circulated concerning 61 potential outbreaks of infectious intestinal disease in persons returning to Scotland from abroad. This was an increase compared to the 30 potential overseas outbreaks reported in 2014, and is very similar to the average for the previous 12 years (2003-2014) of 59 potential overseas outbreaks, but with considerable year-on-year variation.
In 2015, Spain (including the Balearic Islands), Egypt and Turkey were the three most frequently reported countries; these are the same three most frequently reported countries the previous year. In 2015, ten countries were each associated with one potential outbreak.
Cryptosporidium was the most frequently identified pathogen associated with potential overseas outbreaks in 2015 and was reported from 26 (43%) potential outbreaks, this is in contrast to the previous four years during which Salmonella was the most frequently reported pathogen. Salmonella did nonetheless account for 36% of potential overseas outbreaks in 2015, no major change from the 40% of outbreaks it was associated with in 2014.
To date in 2016 information has been circulated on four potential overseas outbreaks, three of Salmonella and one of E. coli. 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 reports not only on outbreaks of infectious intestinal disease but also on single cases of VTEC infection who report travel outside Scotland in the 14 days prior to the onset of symptoms.
During 2015, HPS disseminated information on 11 cases of E. coli O157 and two non-O157 cases, who had travelled outside Scotland in the 14 days prior to onset of symptoms.
To date in 2016 information has been disseminated on four cases of E. coli O157 with travel outside Scotland 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. Further information on the overseas outbreak surveillance system can be obtained from Alison Smith-Palmer.