Between 1 October 2016 and 31 August 2017, 51 Legionnaires' disease (LD) cases from the United Kingdom, Sweden and the Netherlands were identified with associated travel to Dubai. Cases did not all stay in the same accommodation, indicating that no single accommodation could be the source for all these infections. While local investigations continue into other potential sources, clinicians should remain alert to the possibility of LD among travellers returning from Dubai with respiratory illness

Brandsema, Petra

Cameron, Ross

Dabrera, Gavin

Lofdahl, Margareta

McMenamin, Jim

Naik, Falguni

Pebody, Richard

Phin, Nick

Eurosurveillance

Between 1 October 2016 and 31 August 2017, 51 Legionnaires’ disease (LD) cases from the United Kingdom, Sweden and the Netherlands were identified with associated travel to Dubai. Cases did not all stay in the same accommodation, indicating that no single accommodation could be the source for all these infections. While local investigations continue into other potential sources, clinicians should remain alert to the possibility of LD among travellers returning from Dubai with respiratory illness.</jats:p

Gavin Dabrera

Petra Brandsema

Margareta Lofdahl

Falguni Naik

Ross Cameron

Jim McMenamin

Richard Pebody

Nick Phin

Crossref

Increase in Legionnaires’ disease cases associated with travel to Dubai among travellers from the United Kingdom, Sweden and the Netherlands, October 2016 to end August 2017

Web-based Archive of RIVM Publications

1www.eurosurveillance.orgRapid communicationsIncrease in Legionnaires’ disease cases associated with travel to Dubai among travellers from the United Kingdom, Sweden and the Netherlands, October 2016 to end August 2017G Dabrera ¹ , P Brandsema ² , M Lofdahl ³ , F Naik ¹ , R Cameron ⁴ , J McMenamin 4 , R Pebody ¹ , N Phin ¹ 1. 1. Centre for Infectious Disease Surveillance and Control, National Infection Service, Public Health England, London, United Kingdom2. Epidemiology and Surveillance of infectious diseases, Centre for Infectious Disease Control Netherlands, National Institute for Public health and the Environment (RIVM), Bilthoven, The Netherlands3. Surveillance and Coordination, Folkhalsomyndigheten, Stockholm, Sweden4. Health Protection Scotland, NHS National Services Scotland, Glasgow, United KingdomCorrespondence: Gavin Dabrera (legionella@phe.gov.uk)Citation style for this article: Dabrera G, Brandsema P, Lofdahl M, Naik F, Cameron R, McMenamin J, Pebody R, Phin N. Increase in Legionnaires’ disease cases associated with travel to Dubai among travellers from the United Kingdom, Sweden and the Netherlands, October 2016 to end August 2017. Euro Surveill. 2017;22(38):pii=30618. DOI: http://dx.doi.org/10.2807/1560-7917.ES.2017.22.38.30618 Article submitted on 04 September 2017 / accepted on 21 September 2017 / published on 21 September 2017Between 1 October 2016 and 31 August 2017, 51 Legionnaires’ disease (LD) cases from the United Kingdom, Sweden and the Netherlands were identified with associated travel to Dubai. Cases did not all stay in the same accommodation, indicating that no single accommodation could be the source for all these infec-tions. While local investigations continue into other potential sources, clinicians should remain alert to the possibility of LD among travellers returning from Dubai with respiratory illness.In December 2016, the European Centre for Disease Prevention and Control (ECDC) reported an increase in Legionnaires’ disease (LD) cases associated with travel to Dubai, United Arab Emirates (UAE) [1] based on cases reported to ELDSNet (European Legionnaires’ disease surveillance network), an ECDC–operated sur-veillance system among European Union (EU) coun-tries, Iceland and Norway [2] for laboratory-confirmed, travel-associated LD (TALD) cases who stayed in com-mercial accommodation site(s) (e.g. hotels) during the 2–10-day incubation period. As this increase in Dubai-associated TALD cases continues, we describe cases reported with symptom onset between 1 October 2016 and 31 August 2017 among residents from the United Kingdom (UK), Sweden and the Netherlands (the three countries that were initially reporting the largest num-bers of cases). We describe the ongoing situation as at 18 September 2017 to provide further insight into the observed increase and create awareness among phy-sicians and travellers returning with compatible symp-toms to consider legionella as a differential diagnosis [1].Case definitionCases were classified as any person resident in the UK, Sweden or the Netherlands with clinical or radiologi-cal evidence of pneumonia, laboratory confirmation of Legionella infection and stay in Dubai during the 2–10 days before symptom onset. Laboratory confir-mation included methods fulfilling the EU confirmed case definition (culture testing, urine antigen testing or serology) or the detection of Legionella spp. by PCR [3]. All patients meeting the case definition with symp-tom onset between 1 October 2016 and 31 August 2017, were described by age, sex, tobacco smoking status, presence of underlying medical conditions, laboratory confirmation method and where available, sequence-based typing.SurveillanceThe LD surveillance systems in our countries have been described elsewhere [4-7]. In brief, LD must be notified by medical practitioners to public health authorities, who interview the patient or close family members to identify potential legionella exposures during the incubation period, including any travel away from the patient’s main residence (national and/or foreign travel).Description of casesThere were 51 laboratory-confirmed LD cases associ-ated with travel to Dubai with symptom onset between 1 October 2016 and 31 August 2017. Of these, 36 were reported from the UK, eight from Sweden and seven from the Netherlands. Over two thirds of cases were men (36/51). The median age for all cases was 2 www.eurosurveillance.org66 years (interquartile range (IQR): 57.5−72.0; range: 36−84 years). For cases with available information, 23/43 were smokers or ex-smokers and 18/44 had at least one long-term underlying medical condition. Just over a quarter of cases with hospitalisation informa-tion (10/36), required critical care admission. Figure 1 shows the distribution of cases by symptom onset date, and indicates cases concentrated in October 2016, with continuing elevated numbers in November, early December 2016, February and April 2017.The most frequently used diagnostic method was uri-nary antigen testing (45/51 cases) with PCR methods used in 17/51 cases and culture in 7/51 cases; 14 cases were diagnosed using more than one type of labora-tory test. Most cases were speciated as Legionella pneumophila (50/51), while the remaining case was Legionella spp. unknown. Serogroup was known for 16 cases: 13 were serogroup 1, two serogroup 13 and one serogroup 2–14. Full sequence-based typing (ST) was available for nine cases (6 cases ST616, 3 cases ST1327) and three cases had partial ST profiles.The median number of days within the incubation period that cases spent in Dubai was six (IQR: 4−8, range 2–9 days). Eleven cases spent the whole incuba-tion period in Dubai. Four cases also travelled to other emirates within UAE; six had foreign travel to four dif-ferent countries in addition to UAE, during the incuba-tion period.In relation to potential aerosol exposures in Dubai, 44 of 48 cases with available information had used show-ers, while 29 of 45 recalled exposures to fountains and water features. Use of swimming pools (12/40) and spa pools (5/39) was less frequent among cases. Other activities for cases included boat trips (7 cases), foun-tain shows and visits to the gold souk (3 cases each).The 51 cases were associated with 45 individual accom-modation sites. Most (43/51) cases stayed in commer-cial accommodation: 27/43 in single accommodation (sites where there were no other associated cases in the previous two years), 15/43 in cluster accommoda-tion (sites where there were two or more associated cases in a two-year period) and 1/43 in a commercial accommodation with limited information (preventing the identification of associated cases in the previ-ous two years); seven stayed in private accommoda-tion and for one case the accommodation type was unknown. Significantly, in addition to the seven pri-vate accommodation sites, there were 27 different commercial accommodation sites not previously asso-ciated with LD cases (i.e. not part of clusters them-selves). Three of the 51 cases were associated with a foreign-travel related cluster in other countries. The cases for whom sequence-based typing was available were all linked to different accommodations sites. The average case numbers recorded for each month by onset date between October and August for 2013−14, 2014−15, 2015−16 and - separately for October 2016 to August 2017 for our three countries, are summarised in the Table, which shows that during the investigation period, the number of Dubai-associated TALD cases was higher than the rounded average case numbers of 3−12 cases for the equivalent 11-month period for each of our countries between 2013 and 2016.Figure 2 shows that cumulative case numbers for all three countries were particularly elevated from September 2016 onwards, compared with average monthly cumulative case numbers reported for 2013–15. This was sustained for all three countries through to August 2017.DiscussionHere we report an increase in Dubai-associated TALD cases, above the historical averages for each of our Figure 1Cases of Legionnaires’ disease associated with travel to Dubai in residents of the United Kingdom, Sweden and the Netherlands, 1 October 2016−31 August 2017 (n=51)01234501 Oct8 Oct15 Oct22 Oct29 Oct5 Nov12 Nov19 Nov26 Nov03 Dec10 Dec17 Dec24 Dec31 Dec07 Jan14 Jan21 Jan28 Jan04 Feb11 Feb18 Feb25 Feb11 Mar04 Mar18 Mar25 Mar01 Apr08 Apr15 Apr22 Apr29 Apr06 May13 May20 May27 May03 Jun10 Jun17 Jun24 Jun01 Jul08 Jul15 Jul22 Jul29 Jul05 Aug12 Aug19 Aug26 AugNumber of cases2016 2017Date of symptom onsetUnited Kingdom Sweden The Netherlands3www.eurosurveillance.orgthree countries. As our countries’ travellers accounted for the majority of the increase when first observed by ECDC [1], they provide an important insight into this situation.The hypothesis of increased LD risk related to travel to Dubai rather than increased risk in the countries of res-idence is supported by the simultaneous peak in cases occurring from September 2016 onwards for all three countries (Table). Additionally, there were no changes in LD surveillance and no community outbreaks in our countries that provide an alternative explanation. Six cases were typed as ST616, a strain observed in our surveillance only in cases associated with travel to Dubai. In addition, ST1327 has been associated with travel to Dubai for all but one case in our surveillance (data not shown). Furthermore, 11 cases spent their entire incubation period in Dubai. These findings sup-port the assertion that these infections occurred within Dubai.There are several potential explanations for the observed increase in cases associated with travel to Dubai; one could be changes in patient-level risk fac-tors for infection. However, this is unlikely to explain the increase as patient-level risk factors such as under-lying medical conditions, current or previous smoking status were reported for 36 cases, which is consistent with almost three quarters among LD cases, previously reported in England and Wales in 2015 [7].Another potential explanation is an increase in travel-lers, although overall changes in traveller numbers do not solely explain the scale of the observed increase. UK traveller numbers to Dubai increased by 5% for the calendar year from 2015 to 2016 [8] while travellers to UAE from the Netherlands increased by 9% between November 2016 and April 2017 compared with the same time period one year earlier (data not shown); however, the proportion of the latter dataset related to Dubai specifically is unknown. Due to the incomplete availability of Dubai-specific travel data for all three countries as well as the limited comparability of these available data sources, we have not specifically esti-mated an incidence rate for LD cases associated with travel to Dubai.Another explanation is one or more new legionella source(s) in Dubai, although there is limited informa-tion available from local investigations. TALD investi-gations generally focus on accommodation sites [2]. However, these accommodation sites seem an unlikely explanation as only 15 cases were associated with clus-ter sites. Therefore, wider environmental investigations in addition to commercial accommodation sites are required to identify and control the source of infection.ECDC reported that there has been no increase in pneu-monia notifications locally in Dubai between October and December 2016 [9]. This could be explained by an environmental source where foreign travellers are more frequently exposed than local residents. Alternatively, the local Dubai population is predominantly young, with only 8.7% in the ≥50 age group in 2016, and there-fore is potentially at lower LD risk [10].Several public health actions have been undertaken. To support local investigations, anonymised epidemio-logical information collected by the public health agen-cies in the EU countries has been shared with public health authorities in Dubai by ECDC and the World Health Organization (WHO). This supplements our rou-tine international TALD case reporting via ELDSNet. Similar information sharing for 17 TALD cases from dif-ferent countries was successful in controlling an out-break in Lazise, Italy, in 2011 [11].Although the absolute numbers of Dubai-related TALD cases are low in comparison to annual visitor numbers, information for travellers about LD symptoms to be aware of has been published on websites of national public health institutes and on websites for travel health [12-14].This investigation highlights the benefits of interna-tional TALD surveillance (such as ELDSNet) in facilitat-ing identification and alerting of increases in cases related to specific destinations; in addition, ascertain-ment of cases linked to private accommodation, as well as commercial accommodation, through such surveil-lance, would be important to determine the full scale of TALD in this particular situation. It should be noted that there would be an inherent delay in reporting to ECDC due to the time taken for diagnosis and collation of relevant epidemiological data.Figure 2Cumulative number of Legionnaires’ disease cases associated with travel to Dubai in residents of the United Kingdom, Sweden and the Netherlands, January 2016−August 2017 compared to the average for 2013−150Jan Feb Mar Apr510152025303540Number of casesMay Jun Jul Aug Sep Oct Nov DecMonth of symptom onsetAverage 2013–1520162017Cumulative numbers for year to date, shown for 2016 and January–August 2017, with average cumulative numbers for 2013–15 for United Kingdom, Sweden and the Netherlands, combined.4 www.eurosurveillance.orgSeasonal trends in travel to Dubai highlight the poten-tial for further cases occurring in the coming months; for instance travel from the UK is particularly high dur-ing the winter and spring seasons [8]. Thus further environmental investigations remain important. While local public health authorities in Dubai conduct pub-lic health investigations and implement controls, clini-cians should remain vigilant for LD symptoms among returning travellers, to aid prompt diagnosis and treatment.AcknowledgementsWe are grateful for the contributions of Lena Sundqvist, Michael Devine, Robert Smith and other microbiology and public health colleagues to the investigation and surveil-lance of Legionnaires’ disease cases within our countries.Conflict of interestNone declared.Authors’ contributionsGD led the drafting of the article; GD, FN, ML, PB, RC con-tributed to description of cases. All authors contributed to development and refinement of this manuscript.References1. European Centre for Disease Prevention and Control (ECDC). Increase of cases of Legionnaires’ disease in EU travellers returning from Dubai, October−December 2016. Stockholm: ECDC. [Accessed 20 Jul 2017]. Available from: http://ecdc.europa.eu/en/publications/_layouts/forms/Publication_DispForm.aspx?List=4f55ad51-4aed-4d32-b960-af70113dbb90&ID=1623#sthash.AzaJAuyA.dpuf2. de Jong B, Payne Hallström L, Robesyn E, Ursut D, Zucs P, ELDSNet (European Legionnaires’ Disease Surveillance Network). Travel-associated Legionnaires’ disease in Europe, 2010.Euro Surveill. 2013;18(23):20498.PMID: 237871283. European Commission. Commission Implementing Decision of 8 August 2012 amending Decision 2002/253/EC laying down case definitions for reporting communicable diseases to the Community network under Decision No 2119/98/EC of the European Parliament and of the Council. Luxembourg: Publications Office of the European Union. L262. 27 Sep 2012. Available from: http://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32012D0506&qid=1428573336660&from=EN#page=174. Cameron RL, Pollock KGJ, Lindsay DSJ, Anderson E. Comparison of Legionella longbeachae and Legionella pneumophila cases in Scotland; implications for diagnosis, treatment and public health response.J Med Microbiol. 2016;65(2):142-6. DOI: 10.1099/jmm.0.000215 PMID: 267042975. Brandsema PS, Euser SM, Karagiannis I, Den Boer JW, Van Der Hoek W. Summer increase of Legionnaires’ disease 2010 in The Netherlands associated with weather conditions and implications for source finding.Epidemiol Infect. 2014;142(11):2360-71. DOI: 10.1017/S0950268813003476 PMID: 245764866. Folkhälsomyndigheten [Swedish Public Health Agency]. Sminet: elektronisk anmälan av smittsamma sjukdomar. [Sminet: electronic notification of communicable diseases]. Stockholm: Folkhälsomyndigheten. [Accessed 10 Jul 2017]. Swedish. Available from: http://www.sminet.se/?page_id=47. Public Health England (PHE). Legionnaires’ disease in England and Wales – 2015. London: PHE. [Accessed 10 Jul 2017]. Available from: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/562685/LD_annual_report_2015__final_.pdf8. Dubai Corporation of Tourism and Commerce Marketing. Dubai tourism 2016 : performance report. Dubai: Dubai Corporation for Tourism and Commerce Marketing; 2017. Available from: https://www.visitdubai.com/en/tourism-performance-report9. European Centre for Disease Prevention and Control (ECDC). Epidemiological update: Legionnaires’ disease cases associated with travel to Dubai, 24 May 2017. Stockholm: ECDC; 24 May 2017. Available from: https://ecdc.europa.eu/en/news-events/epidemiological-update-legionella-dubai-24-may-201710. Government of Dubai. Population by Gender and Age Groups - Emirate of Dubai. Dubai Statistics Center. [Accessed 20 Jul 2017]. Available from: https://www.dsc.gov.ae/en-us/Themes/Pages/Population-and-Vital-Statistics.aspx?Theme=4211. Rota M, Scaturro M, Fontana S, Foroni M, Boschetto G, Trentin L,  et al.  Cluster of travel-associated Legionnaires disease in Lazise, Italy, July to August 2011. Euro Surveill. 2011;16(40):19982.PMID: 2199637912. National Travel Health Network and Centre (NaTHNaC). TravelHealthPro. Legionellosis in United Arab Emirates. London: NaTHNaC. [Accessed 6 Jul 2017]. Available from: https://travelhealthpro.org.uk/updates.php?base=146213. Rijksinstituut voor Volksgezondheid en Milieu (RIVM). Legionella in Dubai. Bilthoven: RIVM. 24 Mar 2017.Dutch. Available from: http://www.rivm.nl/Onderwerpen/L/Legionella/Legionellose_opgelopen_tijdens_vakantie/Legionella_in_Dubai14. Public Health England (PHE). Risk Assessment on Legionnaires’ disease associated with travel to Dubai. London: PHE; 20 Apr 2017. Available from: https://www.gov.uk/government/publications/legionnaires-disease-associated-with-travel-to-dubai License and copyrightThis is an open-access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0) Licence. You may share and adapt the material, but must give appropriate credit to the source, provide a link to the licence, and indi-cate if changes were made.This article is copyright of the authors, 2017.TableAverage numbers of Legionnaires’ disease cases associated with travel to Dubai between 1 October and 31 August for 2013−14, 2014−15 and 2015−16 compared with case numbers for 2016−17Country of residenceNumber of LD cases associated with travel to Dubai (1 Oct 2016−31 Aug 17)Rounded average number of LD cases associated with travel to Dubai (1 Oct 2013−15 to 31 Aug 2014−16)United Kingdom 36 12Sweden 8 3The Netherlands 7 4LD: Legionnaires’ disease.

Increase in Legionnaires' disease cases associated with travel to Dubai among travellers from the United Kingdom, Sweden and the Netherlands, October 2016 to end August 2017.

NARCIS 

http://rivm.openrepository.com/rivm/bitstream/10029/621620/2/eurosurv-22-38-2.pdf

Increase in Legionnaires' disease cases associated with travel to Dubai among travellers from the United Kingdom, Sweden and the Netherlands, October 2016 to end August 2017.

Abstract

Similar works

Full text

Available Versions

Crossref

Web-based Archive of RIVM Publications

NARCIS