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 consider 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, when additional cases are identified in Scotland and additional information becomes available, this information is also passed to the relevant national surveillance centre in order to facilitate local investigations.
In 2014, information was circulated concerning 30 potential outbreaks of infectious intestinal disease in persons returning to Scotland from abroad. This was an increase compared to the 20 potential overseas outbreaks reported in 2013, but is still lower than the other years 2003-2013. Since 2003, information has been circulated on a total of 714 potential overseas outbreaks.
In 2014, Spain (including the Balearic Islands) and Turkey were the two most frequently reported countries – each associated with seven (23%) of the 30 potential outbreaks. By contrast, Egypt, which had in 2013 been the most frequently reported country accounting for seven (35%) of the outbreaks, was in 2014 associated with only three (10%). In 2014, ten countries and a cruise were each associated with one potential outbreak.
Salmonella was the most frequently identified pathogen associated with potential overseas outbreaks in 2014 and was reported from 12 (40%) potential outbreaks. This is consistent with trends in recent years with Salmonella also the most frequently reported pathogen in 2013, 2012 and 2011, when it accounted for 60%, 41% and 58% of outbreaks respectively. There were also ten potential outbreaks of Cryptosporidium, three of Escherichia coli, two of Shigella and one each of norovirus and cylospora and one where the pathogen had not been confirmed at the time of reporting.
To date in 2015 information has been circulated on four potential overseas outbreaks, one each of Cryptosporidium, Shigella, Salmonella and 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 2014, HPS disseminated information on seven such cases of E. coli O157 while, in 2015 to date, a further three cases have been reported.
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.