On 6 June 2017, the World Health Organization (WHO) published updates to its ‘Essential Medicines List’ (EML). Read more here.

Eurosurveillance is on the updated list of the Directory of Open Access Journals and in the SHERPA/RoMEO database. Read more here.

Follow Eurosurveillance on Twitter: @Eurosurveillanc

In this issue

Home Eurosurveillance Edition  2013: Volume 18/ Issue 32 Article 3
Back to Table of Contents
Previous Download (pdf)

Eurosurveillance, Volume 18, Issue 32, 08 August 2013
Surveillance and outbreak reports
International infectious disease surveillance during the London Olympic and Paralympic Games 2012: process and outcomes
  1. Travel and Migrant Health Section, Health Protection Services, Colindale, Health Protection Agency (now Public Health England), London, United Kingdom
  2. Surveillance and Response Support Unit, European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden
  3. Emerging Infections and Zoonoses Section, Health Protection Services, Colindale, Health Protection Agency (now Public Health England), London, United Kingdom
  4. National Travel Health Network and Centre, University College Hospital, London, United Kingdom
  5. National Travel Health Network and Centre, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
  6. Microbial Risk Assessment & Behavioural Science, Emergency Response Department, Health Protection Services, Health Protection Agency (now Public Health England), Porton Down, United Kingdom
  7. National Specialist Epidemiology and Intelligence, Health Protection Services, Colindale, Health Protection Agency (now Public Health England), London, United Kingdom
  8. Members of the international team are listed at the end of the article

Citation style for this article: Jones J, Lawrence J, Payne Hallström L, Mantero J, Kirkbride H, Walsh A, Jermacane D, Simons H, Hansford KM, Bennett E, Catchpole M, on behalf of the international team. International infectious disease surveillance during the London Olympic and Paralympic Games 2012: process and outcomes. Euro Surveill. 2013;18(32):pii=20554. Article DOI:
Date of submission: 14 November 2012

Surveillance for possible international infectious disease threats to the Olympic and Paralympic Games in London, United Kingdom, was conducted from 2 July to 12 September 2012 by a collaborative team comprising representatives from the Health Protection Agency (Public Health England since April 2013), the European Centre for Disease Prevention and Control and the National Travel Health Network and Centre. Team members enhanced their usual international surveillance activities and undertook joint risk assessments of incidents identified as relevant through an agreed set of criteria designed for the Games and using tools developed for this purpose. Although team members responded to a range of international disease incidents as part of their routine roles during this period, no incident was identified that represented a threat to the Games. Six incidents were highlighted by the team that were likely to attract media attention and hence could generate political and public concern. Responding to such concern is an important aspect of the overall public health management of mass gathering events. The lessons learned about the process and outcomes of the enhanced international surveillance will help inform planning by future hosts of similar events.


The Olympic Games are the largest international sporting ‘mass gathering’ event in the world, followed by the Paralympic Games. In 2012, both events were hosted by the United Kingdom (UK), centred on the Olympic Park in East London, but with events also taking place in other venues across the country. The Games took place from 27 July to 12 August (Olympics) and from 29 August to 9 September (Paralympics). More than 25,000 athletes and officials took part from over 200 countries. Many more tens of thousands of journalists, workers and volunteers were also involved, with total spectator attendance estimated to be around 10 million across both events at all venues combined.

In common with other mass gatherings, large international sports events present a range of complex challenges to host countries, including public health preparedness [1]. The types of infectious disease (ID) incidents that are relevant for mass gatherings have been previously described [2], but  none were reported in association with any of the last four Olympic Games [3]. Considerable concern is, however, generated by the potential impact of such incidents on the Games, the host population and countries to which athletes and visitors return. Highly infectious diseases with airborne/droplet transmission and short incubation periods pose the greatest potential threat to large public gatherings such as the Games and there are examples where such infections have been transmitted in similar contexts [4-7]. Considerable effort is directed towards early identification of potential ID threats associated with such events, often including those that may arise outside the host country [8,9], so that appropriate responses may mitigate any significant risk detected.

With high levels of global travel, migration and economic interdependence as well as increased speed of transport around the world, international ID surveillance is now an important and routine part of many countries’ general public health preparedness. Both the World Health Organization (WHO) and the European Commission have established restricted-access web-based communication platforms so that Member States can share information about public health incidents; these include the WHO Event Information Site for International Health Regulations (IHR) national focal points and the European Early Warning and Response System (EWRS). These platforms provide alerts about significant international public health incidents to Member States, which may also perform additional information gathering of their own.

Epidemic Intelligence (EI) is a form of surveillance that refers to a process of rapid systematic collection, collation, validation, analysis and risk assessment of information about potential public health incidents from a variety of sources [10,11]. Its purpose is to permit earlier detection of potential health threats so that timely public health responses can be recommended and enacted. EI activities are implemented at different levels and using various modalities by many national and international public health institutions. They complement standard surveillance data with formal and informal reports about incidents of potential public health relevance (event-based surveillance, EBS) [12]. EBS has been revolutionised in the last 10 years by the rapid development of web technologies and electronic communication: these changes have defined a crucial role for open access online information for risk detection and monitoring activities, although they have also greatly increased the amount of background ‘noise’ of ID incidents requiring evaluation.

International ID surveillance for the 2012 Olympics and Paralympics (also known as London 2012) was conducted by a collaborative ‘international team’ comprising several organisations that have routine roles in EI. The work of these groups overlaps to a certain degree, but each has its own particular responsibilities and therefore also its own criteria for  selection  of items for further monitoring, assessment or response, as outlined below.

  • The National Travel Health Network and Centre (NaTHNaC) and the Travel and Migrant Health Section (TMHS) of the Health Protection Agency (HPA) (Public Health England since 1 April 2013, but referred to throughout this article as the former organisation) are primarily concerned with international ID incidents that may have an impact on British travellers. They also produce clinical updates for health professionals about relevant incidents [13].
  • The Emerging Infections and Zoonoses (EIZ) and Microbial Risk Assessment (MRA) sections of the HPA are concerned with assessing and responding to potential ID threats to UK public health. They provide evidence-based risk assessments of ID incidents to inform policy, planning, public health countermeasures and communications. Both sections produce regular summaries of potential threats for relevant professionals.
  • The European Centre for Disease Prevention and Control (ECDC) is concerned with detecting, monitoring, assessing and communicating ID issues of concern to the European Union and supporting the coordinated response to potential ID threats to the public health of the European Union [14]. ECDC produces regular reports, epidemiological updates and risk assessments.

The primary purpose of international ID surveillance during London 2012 was to identify ID incidents occurring anywhere in the world outside the UK that might have an adverse impact on London 2012,  e.g. by affecting the health of competitors/visitors/others involved in the Games (with or without potential for subsequent export of disease from the UK and/or spread within the UK), or by affecting the smooth running of the Games and/or travel to and from the UK or by attracting media attention/public and political concern irrespective of whether that concern was justifiable.

Secondary purposes included identifying international ID incidents during London 2012 that might require provision of advice to clinicians seeing imported cases, or implementation of particular public/port health measures.

This paper outlines the international ID surveillance carried out during London 2012 and describes the results generated during the 10.5-week (73 days) enhanced surveillance period, along with its personnel requirements. It also aims to share lessons learned about the process and outcomes of this, as compared with routine activity, to help inform planning by future hosts of similar events.


International surveillance for London 2012 was based on an enhanced ‘business as usual’ model and was part of wider surveillance activity that has been previously described [3]. The international team began working together early in 2010 and over the next two years, developed an enhancement of their normal processes that was extensively tested and refined to maximise sensitivity and specificity of identification of ID incidents relevant for the Games, and to use resources efficiently.

The process adopted for daily international surveillance is outlined in Figure 1. Of the collaborating groups, only ECDC has a dedicated unit that undertakes extensive EI on a 24/7 basis. Thus they led on this aspect of the process, enhancing and modifying their work to provide tailored support for the HPA to detect, monitor and assess potential international ID risks to London 2012.

Figure 1. Daily scheme for international surveillance during the London Olympic and Paralympic Games 2012 (2 July–12 September 2012)

ECDC EI activity focuses primarily on the use of open access web-based information. ECDC has collaborated with the developers of several EBS web systems that are able to gather, filter and classify public health information in real-time. Most of these systems are fully automated; however, some of them include a human filtering component. The EBS systems that were modified for the specific surveillance needs of London 2012 are shown in Table 1. In addition to these systems, information was also obtained from online discussion forums, restricted-access website communication platforms for disease-specific European surveillance networks coordinated by ECDC, and other network sources for evaluation of anticipated threats, such as influenza epidemics in the southern hemisphere.
Table 1. Resources to support the international infectious disease incident surveillance function during London Olympic and Paralympic Games 2012 (2 July–12 September 2012)

The criteria that were developed by the international team for ECDC to use to  select  ID incidents through their EI activity for further joint risk assessment are summarised in the Box. These criteria were aligned with the purposes of the surveillance activity as described above and were informed by a shared evidence-based understanding of the types of international ID incidents that would have the potential to have an impact on the Games. Other parts of the international team contributed information from their own routine EI activity if it fulfilled these criteria, and all contributed to the joint risk assessment of incidents for the Games by means of a daily international risk assessment teleconference. Information about any international incidents identified by any HPA or other Government department personnel (e.g. Department of Health/Foreign and Commonwealth Office) were requested to be sent to the international team led from Health Protection Services, Colindale, rather than independently reported, so that all were subject to the same risk assessment process and a standard risk language was used to report them. Only newly reported incidents or significant changes to baseline epidemiology/clinical picture (e.g. increased severity) or significant changes to the status of ongoing incidents were considered for inclusion in the daily international situation report. In addition to the daily reporting, summaries of any significant changes in global measles and influenza epidemiology were also provided by the international team on a weekly and fortnightly basis respectively.

Box. Criteria used during epidemic intelligence activity to  select  international infectious disease incidents of possible relevance to the London Olympic and Paralympic Games 2012 (2 July–12 September 2012)  

Table 1 summarises the range of resources that were required to support the international surveillance function. Rotas were developed to cover necessary duties seven days a week throughout the London 2012 surveillance period. The HPA seconded four public health trainees to ECDC to support EI activity, and a liaison officer from ECDC was also stationed with the national and international infectious disease surveillance departments based at Colindale during the three weeks of the Olympics to facilitate the day-to-day collaboration.

Analysis of ID incidents identified during the surveillance period comprised: (i) analysis of incidents that fulfilled the criteria (all those contained within the HPA Olympic international surveillance database); and (ii) analysis of other incidents discussed at the international risk assessment teleconference but which did not fulfil the criteria and were not therefore imported into the database. This involved detailed review of all notes from the daily teleconference.  All incidents were analysed in Microsoft Excel.


The results of daily international surveillance for London 2012 for the entire surveillance period are summarised in Figure 2. In total, 49 separate incidents were identified as relevant according to the Games criteria and therefore required further risk assessment by the international team. Of these, 17 were related to gastrointestinal infections such as salmonellosis, cholera and Escherichia coli infection, 12 to childhood infections such as hand, foot and mouth disease, pertussis and measles, seven to influenza, seven to zoonoses such as anthrax and those due to infection with West Nile virus, hantavirus and Hendra virus, three to viral haemorrhagic fevers such as Lassa and Ebola and a further three to other infections. In terms of the geographical location of these incidents, 18 were reported in Europe, 10 in North America, eight in Asia, seven in Africa, four in Oceania and two in South and Central America. Of the 17 gastrointestinal disease incidents, nine had specific foods implicated as the source and the international team followed up six of these with the UK Food Standards Agency. None of these incidents involved food that was known to be imported into the UK.

Figure 2. Results of enhanced daily international infectious disease surveillance for the London Olympic and Paralympic Games 2012 (2 July–12 September 2012)a


The international team highlighted 13 items (six incidents and seven updates on those incidents) in their daily contributions to the national infectious disease surveillance situation report.  None of these were assessed as posing an actual threat to the Games; however, all fulfilled the criterion of potentially ‘attracting significant UK media attention or public or political interest’. The six new incidents included (with the initial source of the information) were:

  1. Acute respiratory syndrome in Cambodia, later confirmed as hand, foot and mouth disease caused by enterovirus-71 (IHR)
  2. Acute watery diarrhoea in Cuba, later confirmed as cholera (Cuban Ministry of Health)
  3. Swine-origin H3N2v influenza A in the United States (IHR)
  4. Ebola in Uganda (WHO and Ugandan Government)
  5. Cholera in Nepal (media report)
  6. Hantavirus pulmonary syndrome in Yosemite National Park, United States (United States Centers for Disease Control and Prevention).

Incidents 1, 2, 4 and 6 (plus four updates to these incidents) were included in the final HPA daily situation report to the London Organising Committee for the Olympics and Paralympic Games by the HPA Olympics Coordinating Centre. Throughout the surveillance period, although the southern hemisphere influenza season had started and there were ongoing outbreaks of measles in several countries, there were no significant and/or unexpected changes to the global epidemiology of measles or influenza of relevance to London 2012.

Of the six incidents above, five were notified to the UK under the IHR: two were first identified through IHR and three were first identified through publicly available media and state sources and later reported under the IHR. The time gain of EI over IHR reporting in each case was 3 days (hantavirus pulmonary syndrome in the United States), 10 days (cholera in Cuba) and 15 days (Ebola in Uganda).

The outputs from the simultaneous routine EI activity undertaken by the individual parts of the international team outside the Olympic context are summarised in Table 2.

Table 2. Outcome of routine epidemic intelligence undertaken by parts of the international team during the surveillance period but outside the specific context of the London Olympic and Paralympic Games 2012 (2 July–12 September 2012)

The personnel time required for operation of the enhanced international surveillance system is illustrated in Table 3. In total, 746 additional person-hours over and above routine roles were engaged in Games-specific activity throughout the surveillance period. This does not include the planning, preparation and exercising time by team members in the preceding two-year period.

Table 3. Estimated additional person-hours required over and above routine work for enhanced international infectious disease surveillance during the London Olympic and Paralympic Games 2012 (2 July–12 September 2012)


During the London 2012 surveillance period, the individual parts of the international team continued their routine EI work as well as looking specifically for international ID incidents that might have an impact on the Games. International ID incidents occur all the time and Table 2 demonstrates that over the London 2012 surveillance period, the individual parts of the international team identified and responded to a considerable number of incidents as part of their routine work because they were relevant in some way to their public health perspectives. No international incidents detected during the surveillance period were assessed as likely to pose a disease threat to the Games and no public health responses were therefore developed. It is significant that the only incidents reported by the international team were those that were judged (on the basis of past UK experience) as being likely to attract media attention and hence possible political and public concern. Alerting the press office to the possibility of media interest so that responses can be developed as necessary is an important aspect of the overall public health management of large public events.

The combination of the enhanced EI work of ECDC, supplemented by the routine EI work of the various groups in the international team, gave the system high sensitivity for detection of potential threats. It is very unlikely that any incidents of significance for the Games were missed – a view reinforced by the fact that during the surveillance period there were no reports of ID incidents associated with the Games that were linked to overseas incidents. The incident  selection  criteria developed for EI also gave the process high specificity, thus improving the efficiency of the joint risk assessment process.

The fact that no international ID incidents likely to impact on London 2012 were identified is perhaps not surprising. Likelihood of impact on an event from an overseas ID incident will broadly depend on the nature of the disease (including mode of transmission and incubation period), the number of cases likely to be imported in a relevant time frame (which in turn depends on population connections between the location of the international incident and the host country and, in particular, attendees of the event), the nature of the event, and the ID epidemiology and public health preparedness of the host country. The sanitary and public health infrastructure in the UK, and the absence of the requisite arthropods and/or environmental conditions for most tropical vector-borne diseases, both reduce the likelihood that importation of cases of many types of disease might lead to significant public health issues, either in or out of the Games context. The same may not be true for other countries that might host mass gathering events. The criteria that different countries will use in determining which international ID incidents might be significant in relation to any large public events they host will therefore vary according to their particular circumstances, their normal public health concerns and the nature of the event. The risks associated with a large international sporting event such as London 2012 are likely to be different from those associated with a large international religious event such as the Hajj [15]. Large public events occur very frequently in the UK and associated outbreaks of indigenous ID have occasionally been recorded [16-18].. Literature searches, however, identify no reports of large public events in the UK affected by international ID incidents.

Although athletes /officials and spectators attended London 2012 from all over the world, the majority of the nearly 600,000 international visitors to the UK in July and August who came wholly or partly for London 2012 were from mainland Europe [19]. It must be remembered that the UK, and London in particular, is a very popular travel destination. During July to September each year, on average 9 million people visit the UK from overseas and nearly half of these include at least one overnight stay in London [20]. Although the overall epidemiology of ID in the UK is influenced by international population movement [21], with some examples of generally small-scale outbreaks associated with imported disease [22], it is rare for acute ID incidents occurring elsewhere in the world to have a significant impact on the UK, despite the global connectedness of London. This is partly for the reasons outlined above but also because ID incidents that involve significant international spread, while unpredictable, are infrequent. Since the implementation of the latest IHR (IHR 2005) in 2007, the Director-General of WHO has declared only one public health emergency of international concern (pandemic influenza A(H1N1) in 2009 [23]) and before that, the most recent serious global ID incident was Severe Acute Respiratory Syndrome (SARS) in 2003. Influenza A(H1N1)pdm09 involved global transmission over a period of months during which several mass gathering events took place with control measures implemented on a precautionary basis to minimise any potential public health impact [24-26].

The considerable time commitment in the two-year planning and preparation stage by the international team was invaluable. By the time the London 2012 surveillance period began, the enhanced process was established, the supporting resources were all developed and the activity quickly became part of the daily routine, thus allowing most of those involved to continue with their normal non-London 2012 roles. During the operational stage, international surveillance for London 2012 required a total of around 10 additional hours of personnel time per day, and resources available were used in the most efficient way possible by appropriate division of labour. In particular, ECDC had the lead expertise and responsibility for EI activity, enhancing their usual function in this regard, while the HPA took the lead in the risk assessment process. The international collaboration between UK partners and ECDC worked extremely well and also provided valuable training opportunities, with the involvement of both UK public health trainees and a European Programme for Intervention and Epidemiology Training (EPIET) fellow in ECDC activities. Some incidents included in the international situation reports were detected earlier as a result of EI, which could be very important for an actual threat in terms of response. Perhaps a more significant advantage of the robust system developed was, however, the continuous monitoring of incidents and real-time sharing of relevant information for assessment by a group of experts. Early trials demonstrated that there was value in conducting risk assessments with representatives from all parts of the team, since each group brought its own perspective and experience from routine work. Standardising the approach to assess incidents and report on risk, and having only one route for international information in the overall London 2012 surveillance system, were also demonstrated to be valuable in exercises.

The international surveillance model used worked well for the London 2012 situation and resources available. This does not, however, mean that this model is necessary for all other countries hosting similar events in the future. Of the six items identified for inclusion in the daily international situation report, five were reported to Member States by WHO under IHR, though there were time lags associated with three of these. Countries hosting large sporting events in the future will need to consider to what degree they will need to supplement alerting systems such as these with their own, and/or collaborative, EI processes, when determining how to allocate resources to international surveillance among the wide range of public health responses required for such events.

International team

ECDC: Lara Payne Hallström, Jas Mantero, Assimoula Economopoulou, Pasi Penttinen, Angus Nicoll, Edit Szegedi, Sergio Brusin, Bertrand Sudre, Niklas Danielsson, Gianfranco Spiteri, Niels Kleinkauf, Erika Duffell, Edoardo Colzani, Gayle Dolan (UK public health trainee seconded to ECDC), Gavin Dabrera (UK public health trainee seconded to ECDC), Jillian Johnston (UK public health trainee seconded to ECDC), Philip Veal (UK public health trainee seconded to ECDC), Pete Kinross (EPIET fellow); HPA, Health Protection Services, Colindale: Jane Jones, Joanne Lawrence, Karen Wagner, Edgar Wellington, Katie Geary, Hilary Kirkbride, Amanda Walsh, Bengü Said, Dilys Morgan, Catherine O’Connor, Katherine Henderson, Ruth Ruggles; HPA, Microbial Risk Assessment & Behavioural Science, Emergency Response Department, Health Protection Services, Porton Down: Kayleigh Hansford, Emma Bennett, Maaike Pietzsch; National Travel Health Network and Centre: Daiga Jermacane, Hilary Simons, Claire Wong, Lisa Ford, Dipti Patel, Vanessa Field.


  1. World Health Organization (WHO EURO). Health planning for large public events. Copenhagen: WHO EURO; 9 May 2012. Available from:
  2. Abubakar I, Gautret P, Brunette GW, Blumberg L, Johnson D, Poumerol G, et al. Global perspectives for prevention of infectious diseases associated with mass gatherings. Lancet Infect Dis. 2012;12(1):66-74.
  3. Severi E, Heinsbroek E, Watson C, Catchpole M; HPA Olympics Surveillance Work Group. Infectious disease surveillance for the London 2012 Olympic and Paralympic Games. Euro Surveill. 2012;17(31):pii=20232. Available from:
  4. Gutiérrez I, Litzroth A, Hammadi S, Van Oyen H, Gerard C, Robesyn E, et al. Community transmission of influenza A (H1N1)v virus at a rock festival in Belgium, 2-5 July 2009. Euro Surveill. 2009;14(31):pii=19294. Available from:
  5. Blyth CC, Foo H, van Hal SJ, Hurt AC, Barr IG, McPhie K, et al. Influenza outbreaks during World Youth Day 2008 mass gathering. Emerg Infect Dis. 2010;16(5):809-15.
    PMid:20409371 PMCid:PMC2953988 
  6. Pfaff G, Lohr D, Santibanez S, Mankertz A, van Treeck U, Schonberger K, et al. Spotlight on measles 2010: measles outbreak among travellers returning from a mass gathering, Germany, September to October 2010. Euro Surveill 2010;15(50):pii=19750. Available from: 
  7. Ehresmann KR, Hedberg CW, Grimm MB, Norton CA, MacDonald KL, Osterholm MT. An outbreak of measles at an international sporting event with airborne transmission in a domed stadium. J Infect Dis. 1995;171(3):679-83.
  8. Schenkel K, Williams C, Eckmanns T, Poggensee G, Benzler J, Josephsen J, et al. Enhanced surveillance of infectious diseases: the 2006 FIFA World Cup experience, Germany. Euro Surveill. 2006;11(12):pii=670. Available from: 
  9. Kaiser R, Coulombier D. Epidemic intelligence during mass gatherings. Euro Surveill. 2006;11(51):pii=3100. Available from: 
  10. Paquet C, Coulombier D, Kaiser R, Ciotti M. Epidemic intelligence: a new framework for strengthening disease surveillance in Europe. Euro Surveill. 2006;11(12):pii=665. Available from: 
  11. European Centre for Disease prevention and Control (ECDC). Epidemic Intelligence tutorial. Stockholm: ECDC; 2011. Available from: 
  12. World Health Organization Regional Office for the Western Pacific (WPRO). A guide to establishing event-based surveillance. Manila: WPRO; 2008. Available from:  
  13. National Travel Health Network and Centre (NaTHNaC). Health professionals. Clinical updates. London: NaTHNaC. [Last accessed 7 Aug 2013]. Available from:    
  14. Regulation (EC) No 851/2004 of the European Parliament and of the Council of 21 April 2004 establishing a European centre for disease prevention and control. Official Journal of the European Union. Luxembourg: Publications Office of the European Union. 30.4.2004:L 142. Available from:
  15. Ahmed QA, Arabi YM, Memish ZA. Health risks at the Hajj. Lancet. 2006;367:1008-15.
  16. Crampin M, Willshaw G, Hancock R, Djuretic T, Elstob C, Rouse A, et al. Outbreak of Escherichia coli O157 infection associated with a music festival. Eur J Clin Microbiol Infect Dis. 1999;18(4):286-8.
  17. Orr H, Kaczmarski E, Sarangi J, Pankhania B, Stuart J; Outbreak Investigation Team. Cluster of meningococcal disease in rugby match spectators. Commun Dis Public Health. 2001;4(4):316-8.
  18. Morgan D, Gunneberg C, Gunnell D, Healing TD, Lamerton S, Soltanpoor N, et al. An outbreak of Campylobacter infection associated with the consumption of unpasteurised milk at a large festival in England. Eur J Epi. 1994;10(5):581-5.
  19. Office for National Statistics (ONS). London 2012 Games attract over half a million overseas visitors in July and August. Newport: ONS; 11 Oct 2012. News release. Available from:    
  20. Office for National Statistics (ONS). International Passenger Survey. [Last accessed 7 Aug 2013]. Newport: ONS. Available from:    
  21. Health Protection Services. Migrant health: infectious diseases in non-UK born populations in the United Kingdom. An update to the baseline report – 2011. London: Health Protection Agency; 2011. Available from:  
  22. Hahné SJ, Gray SJ, Aguilera JF, Crowcroft NS, Nichols T, Kaczmarski EB, et al. W135 meningococcal disease in England and Wales associated with Hajj 2000 and 2001. Lancet. 2002;359(9306):582-3.
  23. World Health Organization (WHO). Swine flu illness in the United States and Mexico - update 2. Geneva: WHO; 26 Apr 2009. Available from:    
  24. Memish ZA, Ebrahim SH, Ahmed QA, Deming M, Assiri A. Pandemic H1N1 influenza at the 2009 Hajj: understanding the unexpectedly low H1N1 burden. J R Soc Med. 2010;103(10):386.
  25. Lim HC, Cutter J, Lim WK, Ee A, Wong YC, Tay BK. The influenza A (H1N1-2009) experience at the inaugural Asian Youth Games Singapore 2009: mass gathering during a developing pandemic. Br J Sports Med. 2010;44(7):528-32.
  26. Loncarevic G, Payne L, Kon P, Petrovic V, Dimitrijevic D, Knezevic T, et al. Public health preparedness for two mass gathering events in the context of pandemic influenza (H1N1) 2009--Serbia, July 2009. Euro Surveill. 2009;14(31):pii=19296. Available from:
  27. Mawudeku A, Blench M, Boily L, St. John R, Andraghetti R, Ruben M. The Global Public Health Intelligence Network. In: M'ikanatha N, Lynfield R, Van Beneden C, de Valk H, editors. Infectious disease surveillance. Wiley-Blackwell; 2013. p 457-69.    
  28. Brownstein JS, Freifeld CC, Reis BY, Mandl KD. Surveillance Sans Frontières: Internet-based emerging infectious disease intelligence and the HealthMap Project. PLoS Med. 2008;5(7): e151.
    PMid:18613747 PMCid:PMC2443186 
  29. Mantero J, Belyaeva E, Linge JP. How to maximise event-based surveillance web-systems: the example of ECDC/JRC collaboration to improve the performance of MedISys. Luxembourg: Publications Office of the European Union; 2011. Available from:    
  30. von Etter P, Huttunen S, Vihavainen A, Vuorinen M, Yangarber R. Assessment of utility in web mining for the domain of public health. Proceedings of the NAACL HLT 2010 Second Louhi Workshop on Text and Data Mining of Health Documents. Los Angeles, CA: Association for Computational Linguistics; June 2010. p. 29-37. Available from:    
  31. European Centre for Disease Prevention and Control (ECDC). Tools. Threat Tracking Tool (TTT). EPIS. Stockholm: ECDC. [Last accessed 7 Aug 2013]. Available from:

Back to Table of Contents
Previous Download (pdf)

The publisher’s policy on data collection and use of cookies.

Disclaimer: The opinions expressed by authors contributing to Eurosurveillance do not necessarily reflect the opinions of the European Centre for Disease Prevention and Control (ECDC) or the editorial team or the institutions with which the authors are affiliated. Neither ECDC nor any person acting on behalf of ECDC is responsible for the use that might be made of the information in this journal. The information provided on the Eurosurveillance site is designed to support, not replace, the relationship that exists between a patient/site visitor and his/her physician. Our website does not host any form of commercial advertisement. Except where otherwise stated, all manuscripts published after 1 January 2016 will be published under the Creative Commons Attribution (CC BY) licence. You are free to share and adapt the material, but you must give appropriate credit, provide a link to the licence, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.

Eurosurveillance [ISSN] - ©2007-2016. All rights reserved

This website is certified by Health On the Net Foundation. Click to verify. This site complies with the HONcode standard for trustworthy health information:
verify here.