Surveillance and outbreak reports Enhanced epidemic intelligence using a web-based screening system during the 2010 FIFA World Cup in South Africa

J Mantero1, E Szegedi (edit.szegedi@ecdc.europa.eu)1, L Payne Hallström2, A Lenglet, E Depoortere 2, B Kaic3, L Blumberg4, J P Linge5, D Coulombier2 1. Epidemic Intelligence group, European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden 2. Surveillance and Response Support Unit, European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden 3. Croatian National Institute of Public Health, Zagreb, Croatia (deployed at ECDC during the 2010 FIFA World Cup) 4. Division of Public Health Surveillance and Response, National Institute for Communicable Diseases (NICD), Johannesburg, South Africa 5. Global Security & Crisis Management Unit, Joint Research Centre of the European Commission, Ispra, Italy


Introduction The 2010 FIFA World Cup
The 2010 Fédération Internationale de Football Association (FIFA) World Cup took place in South Africa between 11 June and 11 July 2010 [1].It was one of the largest mass gathering events (MGs) ever organised on the African continent, with the participation of 32 national football teams (Figure), including 11 teams from European Union (EU)/ European Economic Area (EEA) countries: Denmark, England, France, Germany, Greece, Italy, the Netherlands, Portugal, Slovakia, Slovenia, and Spain.More than 300,000 foreign football fans visited South Africa to attend the event (around 72,000 (24%) from Europe), in addition to the 10 million tourists who visit South Africa each year [2].

Mass gathering and risk of infectious diseases
The World Health Organization (WHO) defines a mass gathering event (MG) as an event attended by more than 1,000 individuals in a specific location for a specific purpose and for a defined period of time [3].The term 'mass gathering' generally refers to major international public events, such as sporting events or religious gatherings as well as unplanned events with large number of attendees, which can put a strain on the planning and response resources of the hosting community.
Large numbers of visitors in the same area at the same time may increase the risk of communicable disease outbreaks.Several factors contribute to this theoretical increase, such as increased person-to-person transmission of pathogens due to the localised high population density, risk of importation of non-endemic diseases, exportation of endemic diseases, challenges in contact tracing due to visitor mobility and temporary structures such as mass catering and accommodation for visitors.Non-communicable health risks are also relevant, including heat stroke, crowd injury and drug-and alcohol-related conditions.Additionally, as MGs are often high-profile events, other risks such as security or bioterrorism threats also need to be taken into consideration.The increased risk of public health events during MGs poses special challenges for the hosting authorities in terms of public health preparedness and communication.Media attention might lead to the need for timely communication to the general public and to participants' home communities upon their return.

ECDC epidemic intelligence activities
ECDC refers to epidemic intelligence (EI) as the systematic process of collection, validation and analysis of information about potential public health events from a virtually unlimited amount of sources [4,5].Its purpose is to speed up the detection of possible public health events in order to allow the implementation of timely response actions after an adequate risk assessment.This includes real-time monitoring of the risk these events might pose.The EI process uses official data provided by national health authorities through indicator-based surveillance as well as the monitoring of additional information through event-based surveillance.
ECDC activities during a MG focus mostly on the eventbased surveillance component, in particular on the processing of web-based information.To do so, we use advanced technologies, defined as event-based surveillance web systems, which are able to gather, filter and classify public health information online.MedISys is among the EBS web systems most frequently used for EI purposes at ECDC because of its extreme flexibility and possible customisation [6].The system, developed in 2006 by the European Commission's Joint Research Centre, is capable of screening selected publicly available web sources, including online media and government websites, using multilingual categorisation based on alert definitions using keywords in over 40 languages [7,8].Online items of potential public health interest are automatically classified in specific disease categories if they satisfy the corresponding alert definitions, which may contain Boolean operators, proximity operators, wildcard characters and the use of cumulative positive or negative weights with an adjustable threshold.All news items are classified and geo-located in a user interface accessible on the web.

ECDC epidemic intelligence activities during the 2010 World Cup
In line with ECDC's Founding Regulation, which states that the agency's role is to 'identify, assess and communicate current and emerging threats to human health from communicable diseases in order to strengthen Europe's defences against infectious diseases' [9], we undertook to inform EU national health authorities and the European Commission in real time about possible public health risks for EU citizens during the 2010 World Cup.
The aim of this article is to present the adapted ECDC EI strategy developed six months before and put in place specifically for 2010 World Cup, to present the web-technology used for performing event-based

Countries
surveillance for this MG and report findings in terms of identified public health events communicated in real time with public health partners.

Methods
We adapted ECDC's routine EI process [4] for a defined period of time starting two weeks before the beginning of the 2010 World Cup (7 June 2010) and ending one week after the closing ceremony (16 July 2010).The objective was to allow early detection and monitoring of signals of public health events with a potential to pose a risk to participants and visitors.
Routine EI activities were enhanced by expanding the information sources, using a targeted and systematic screening approach using tailored tools (MediSys), determining validation sources, establishing a daily analysis and communication process with regular and specific public health partners and developing specific reports.Processes were then re-integrated into the structure of routine EI activities at ECDC with no additional allocated budget.We benefited from an additional full-time seconded expert (B.Kaic) for weekday additional screening and daily report production.

Screening of public health information potentially relevant to the 2010 World Cup through MedISys
Following a review of the existing list of online media sources screened by MedISys, we added, in collaboration with European Commission's Joint Research Centre, relevant publicly available media web sources and websites of health authorities of the host country, its neighbours and those of the participating countries.
New multilingual alert definitions were set up, which included languages of participating countries not yet covered by the system, geo-terms specific to South Africa in order to locate the information identified (names of regions, provinces, cities, neighbourhoods and game venues) as well as a limited set of communicable diseases and symptoms.The list of diseases and symptoms was based on an ECDC internal assessment of risk of infectious diseases considering official information from the National Institute for Communicable Diseases (NICD) in Johannesburg, public health reports and travel advice issued by national and international organisations worldwide before the event [10][11][12][13].The list of diseases comprised the following: tick bite fever, Crimean Congo haemorrhagic fever, chikungunya, cholera, dengue, food-borne disease, hand, foot and mouth disease, human immunodeficiency virus (HIV) infection, influenza, legionellosis, malaria, measles, meningococcal meningitis, sexually transmitted infections, poliomyelitis, rabies, Rift Valley fever, respiratory syncytial virus infection, rubella, tuberculosis and yellow fever.
Customised pages were then created in MedISys dedicated to the 2010 World Cup, where selected disease alerts were combined with alerts for selected countries in order to create display filters for online information of potential interest (Table 1).

Filtering screened information for potential public health events
• We established criteria to evaluate the web information selected by MedISys regarding public health relevance for the tournament.These were:

Validation and analysis of potential public health events
Information on public health events detected in EU/ EEA countries was validated through routine channels with EU Member States, while those detected outside the EU/EEA (excluding South Africa) were validated through the WHO Regional Office for Europe and the ECDC EI international network.
Public health events identified in South Africa were validated and assessed through information available from the NICD.The NICD undertook daily laboratory surveillance at national level and was a core member of the Public Health Cluster at the National Operations Centre, which was responsible for the risk assessment of each incident/event.The NICD also posted regular official epidemiological updates on the web, providing real-time public information on current outbreaks or diseases of interest in the country, such as measles, influenza and Rift Valley fever.We analysed all validated events at ECDC on a daily basis during regular EI meetings with the participation of ECDC disease-specific experts, taking into consideration the information provided by South Africa and WHO Regional Office for Europe.

Communicating the epidemic intelligence findings
During the entire period of the enhanced surveillance, ECDC produced a daily bulletin summarising the results of the daily EI activities (signal source, public health topic and summary, validation status, ECDC assessment of relevance).This bulletin was shared daily with the NICD, WHO Regional Office for Europe and interested EU Member States.

Results
Targeted ECDC EI activities during the 2010 World Cup were undertaken for six weeks: 21 incidents of potential public health relevance according to ECDC criteria were detected or monitored.Seven of them occurred in South Africa.

Potential public health incidents in South Africa
A short summary of all potential public health threats in South Africa identified or monitored by ECDC during the enhanced surveillance period is shown in Table 2.

Influenza
The football tournament occurred during the expected influenza season in South Africa.Thus, ECDC started to monitor the influenza activity in South Africa before the event, consulting the NICD and WHO reports supplemented with online media reports, which were verified when necessary.Overall, the influenza activity was low to moderate during the tournament.Initially, only influenza B virus was circulating; both A(H3N2) and A(H1N1)pdm09 virus strains were detected later during the surveillance period [10][11][12].Despite some reported cases of influenza among participants and officials, no spread to other participants or officials was identified.We considered the risk of contracting influenza for EU visitors and/or participants as low during the enhanced surveillance period.

Rift Valley fever
There was an ongoing large nationwide outbreak of Rift Valley fever during 2010 in South Africa and there had been some concerns regarding the risk for EU tourists contracting the disease following reports of a German visitor who was thought to have been infected in the country before the start of the event [14].ECDC monitored Rift Valley fever during the enhanced surveillance period using information regularly provided by the NICD and through media reports.However, all confirmed cases were reported in non-tourist areas and in individuals who had had direct contact with infected animal tissue (farm workers, as a result of occupational exposure).The German case was later discarded by the national authorities following a subsequent diagnosis of rickettsial infection [15].

Meningococcal disease
Meningococcal disease in South Africa occurs normally in sporadic outbreaks, mainly during droughts, dry and dusty conditions or winter seasons, with a predominance of Neisseria meningitidis serogroup B and W135.Media attention on this had been particularly intense shortly before the 2010 World Cup following the death due to meningococcal meningitis of a well-known local opera singer who was scheduled to perform during the opening ceremony [16].Because of the risk of infection for unvaccinated visitors, vaccination against meningococcal disease was recommended for visitors and participants before the event by the NICD [13].Updated information about new cases of meningitis was regularly published online by the NICD during the enhanced surveillance period and was included in the daily ECDC bulletin.No cases were reported among visitors and participants.

Measles
There was an ongoing measles outbreak in South Africa during the 2010 World Cup: it began in the second half of 2009, with more than 15,000 cases reported by July 2010 [10][11][12].ECDC closely followed the situation in the country through regular updates provided by the NICD, taking into consideration the likelihood of unvaccinated visitors contracting the virus and the risk of exportation of cases to non-endemic countries.The NICD informed ECDC that there had been a mass vaccination campaign before the event.Measles updates were included in the daily ECDC bulletins in order to draw the attention of EU national health authorities to the importance of vaccination for EU citizens visiting South Africa.ECDC also informed the general public about the need for vaccination through the ECDC website, both before and during the MG.Sporadic cases were also reported in unvaccinated Australian visitors returning from the event [17,18].In September 2010, health authorities in Argentina, a country that has been measles free since 2000, issued public health alerts after confirmed local transmission of measles virus suspected to be linked to measles cases in citizens who visited South Africa during the 2010 World Cup [19].Other measlesfree countries in South America including Brazil and Uruguay also issued public health alerts for measles in the following months [20,21].

Malaria
The risk of contracting malaria in South Africa was considered very low by the NICD and ECDC for participants and visitors, partly because the venues for the games were outside risk areas with high transmission and partly because the games took place during the lowtransmission period.Two fatalities due to malaria were reported in South Korean members of an international dance group visiting South Africa before the World Cup [22].This report led to increased media attention on the risk of malaria in South Africa.The NICD confirmed the low level of risk as initially assessed and indicated that the two cases were thought not to have been infected in South Africa.

Canine rabies
Ten cases of canine rabies were reported in Metropolitan Johannesburg by the NICD [23].However, the authorities considered the occurrence of rabies to be of limited public health concern, with post-exposure prophylaxis confirmed as being readily available [10][11][12]24].Nonetheless, ECDC included the information about the canine cases in the daily ECDC bulletins to raise awareness among national health authorities about the potential risk of exposure for EU visitors.In September 2010, the NICD confirmed a human local case of rabies in Johannesburg in a child with onset of symptoms in August, which was linked to the animal cases reported during the previous weeks in the same city [25].

Food-borne illness
The NICD issued advice for travellers regarding food safety and recommending caution when purchasing food from street vendors or other food outlets.There were two isolated outbreaks of food-borne illness occurring at game venues during the enhanced surveillance period without serious effects, reported first by the media [26,27] and later confirmed by NICD: one with Bacillus cereus as the causative agent, the other with unknown aetiology [11][12].

Potential public health incidents in participating countries during the 2010 World Cup
We considered six events as being of potential public health risk at EU level during the enhanced surveillance period (hepatitis A, Legionnaires' disease, measles (in two countries), dengue and anthrax) but none were deemed relevant for the World Cup (see short description in Table 3).

Potential public health incidents in nonparticipating countries during the 2010 World Cup
ECDC detected or monitored six public health events of potential EU concern in non-participating countries, which were not deemed relevant the event (see short description in Table 4).

Discussion
ECDC seeks to protect EU/EEA citizens from infectious diseases through early detection, monitoring and assessment of public health signals in the EU/ EEA and worldwide.In the case of large MGs attracting participants from all over the world, public health may benefit from specific surveillance activities directed at infectious diseases and other health risks during the event.ECDC carried out enhanced event-based surveillance for the 2010 World Cup to maximise timely detection and risk assessment communication to EU stakeholders concerning relevant infectious diseases circulating among participants at the tournament or occurring globally.Timeliness was achieved by using both official and non-official information sources.The gathering of information was made effective through a daily process making use of a tailored web-based screening tool (MedISys).
There are limitations on the use of public sources and web-screening tools for event-based surveillance.The detection of public health events from official sources is possible but is dependent on the information being made available regularly and in a timely manner in the public domain, e.g. as regional or national surveillance reports (as undertaken by the NICD during the World Cup).When information is gathered from non-official sources, such as the media, the reporting of isolated cases or outbreaks relies solely on what captures the interest of reporters/journalists, e.g. a disease that occurs in a high-profile individual or a public health rumour with political or economic implications.Thus it is important to take into consideration that reports of public health events detected through web-aggregators Our gathered and validated information was shared with all relevant decision-makers in EU Member States as well as the international community through our daily bulletins during the entire enhanced surveillance period.The enhanced surveillance by ECDC offered a rumour-control function as well, exemplified by a supposed plague outbreak in Syria (Table 4), which was reported by the media but quickly discarded after examination of information from the ECDC EI network.
There were no international or local events posing serious risk to the World Cup during the surveillance period apart from the ongoing local measles outbreak, which also affected visitors.The subsequent detection of measles cases in several countries after the World Cup, with secondary transmission in some places, clearly demonstrated the risk of exportation of vaccine-preventable diseases through visitors returning from a hosting country.This pattern was previously reported following a MG when measles occurred among residents of British Columbia, Canada, after the Winter Olympic Games in Vancouver in 2010, leading to the first major outbreak of the disease in the province since 1997 [28].
Regarding the other reported diseases, the majority of cases were community-based or local sporadic cases.Influenza activity was low to moderate and followed the seasonal trends in the country.There was an expected seasonal activity of meningococcal disease, with sporadic cases in the local population [29].
We also monitored media reports, later confirmed, about individuals in Pretoria being in possession of radioactive materials (caesium-137) and trying to sell it for the production of a dirty bomb during the tournament, but this was not considered a risk for the event [30].
Although no major relevant public health events related to the World Cup occurred, ECDC considers the investment of technical preparations and workforce time used in the enhanced surveillance during the World Cup to be justified.The targeted activities carried out by the ECDC EI team during the World Cup allowed the accurate and timely identification and analysis of public health risks during the event for the entire EU/EEA community, thus saving resources for the individual EU Member States.Additions to MedISys continue to be used beyond the specific filters of the 2010 World Cup and contacts and collaboration with public health partners are a long-term legacy for EI activities.
Furthermore, ECDC's enhanced surveillance activities provide an additional safety net to that of other EI actors at an international level, e.g. the Global Public Health Intelligence Network (GPHIN), HealthMap, PULS (an automated news media monitoring platform) and WHO.Redundancy among EI systems provides an added safety system for global public health security.

Conclusions
The enhanced EI activities by ECDC during the 2010 World Cup, together with the close collaboration of the NICD and WHO, allowed the detection, assessment and communication of relevant health threats potentially affecting EU Member States.Tailored EI surveillance for large international MGs should continue as a core function for ECDC.From each MG experience, ECDC learns how to improve its EI procedures, provide a sound basis for how to best support EU Member States and hosting countries worldwide and broaden the existing knowledge base for future MGs.The added value of the ECDC EI support for the national authorities in the hosting countries can vary considerably depending on existing surveillance systems and national surveillance capacities.It is important to define which tools to use for gathering information, to identify specific filtering criteria in collaboration with the authorities in the hosting countries and to clarify the information flow among the public health partners.

Figure
Figure Countries participating in the 2010 FIFA World Cup, South Africa, 11 June-11 July 2010 (n=32)

Table 1
List of MedISys filters created for the 2010 FIFA World Cup, South Africa, 7 June-16 July 2010 Other public health events in South Africa Identify web information about non-infectious disease events of possible public health interest at the game venues (e.g.crowd injuries, heat stroke and security issues)MedISys, developed at the Joint Research Centre of the European Commission, is an Internet-based system that continuously monitors specialist medical sites and news sites to rapidly identify potential threats to public health.
a Algeria, Argentina, Australia, Brazil, Cameroon, Chile, Côte d'Ivoire, Denmark, England, France, Germany, Ghana, Greece, Honduras, Italy, Japan, Mexico, Netherlands, New Zealand, Nigeria, North Korea, Paraguay, Portugal, Serbia, Slovakia, Slovenia, South Korea, Spain, Switzerland, Uruguay and the United States.bNamibia,Botswana, Mozambique, Swaziland, Zimbabwe and Lesotho.•suspected or confirmed cases of communicable diseases of public health relevance for the South Africa (risk of exportation to South Africa and local spread); • incidents occurring in South Africa drawing media attention in the EU, such as outbreaks in tourist areas, crowd injuries, rumours about possible spread of communicable diseases among visitors or participants.

Table 2
Detected or monitored public health events during the 2010 FIFA World Cup, South Africa, 7 June-16 July 2010 in the host country and their relevance for the event The enhanced surveillance period was from 7 June to 16 July 2010.MedISys, developed at the Joint Research Centre of the European Commission, is an Internet-based system that continuously monitors specialist medical sites and news sites to rapidly identify potential threats to public health.
Outbreaks confirmed by the NICD and assessed as local events with limited or no risk for visitors/ participants.It was of no relevance for the 2010 World Cup.ECDC: European Centre for Disease Prevention and Control; FIFA: Fédération Internationale de Football Association; NCID: National Institute for Communicable Diseases, Johannesburg, South Africa; WHO: World Health Organization.

Table 3
Detected or monitored public health events during the 2010 FIFA World Cup, South Africa, 7 June-16 July 2010 in participating countries and their relevance for the event ECDC: European Centre for Disease Prevention and Control; FIFA: Fédération Internationale de Football Association.The enhanced surveillance period was from 7 June to 16 July 2010.MedISys, developed at the Joint Research Centre of the European Commission, is an Internet-based system that continuously monitors specialist medical sites and news sites to rapidly identify potential threats to public health.

Table 4
Public health events detected or monitored during the 2010 FIFA World Cup, 7 June-16 July 2010, in non-participating countries and their relevance for the event The enhanced surveillance period was from 7 June to 16 July 2010.MedISys, developed at the Joint Research Centre of the European Commission, is an Internet-based system that continuously monitors specialist medical sites and news sites to rapidly identify potential threats to public health.
ECDC: European Centre for Disease Prevention and Control; EU: European Union; FIFA: Fédération Internationale de Football Association; WHO: World Health Organization; WPV1: wild poliovirus 1.