MEMBERSHIP
ELDSNet members are the epidemiologists and microbiologists from the 27 EU countries, Iceland and Norway, who were nominated for Legionnaires’ disease surveillance at European level by their designated national authorities (“competent bodies” according to Regulation (EC) No 851/2004, Article 2a).

COORDINATION
ELDSNet is coordinated by ECDC with the support of a coordination group (CG) consisting of network members. The CG meets twice a year and advises ECDC on ways to strengthen and improve Legionnaires’ disease surveillance and prevention in the EU/EEA. The CG also reviews technical documents relevant to the network and assists ECDC in organising the annual network meeting.

METHODS
Definitions
Cases of Legionnaires’ disease are defined as confirmed or probable according to the EU case definition.

Cases of Legionnaires’ disease are defined as travel-associated if the patient stayed at or visited an accommodation site during the disease incubation period, i.e. two to ten days prior to symptom onset.

A cluster of travel-associated cases of Legionnaires’ disease is defined by at least two such cases being associated with the same accommodation site within two years (based on date of onset).

Surveillance of Legionnaires’ disease
Once annually, Member States send epidemiological data on all cases of Legionnaires’ disease that were notified to them in the preceding year to the European Surveillance System (TESSy) database. ECDC analyses these data to detect and monitor trends and to generate hypotheses for further research.

By contrast, surveillance of travel-associated disease is carried out on a day-to day basis to inform urgent public health action aiming to prevent subsequent cases. Each travel-associated case of Legionnaires’ disease diagnosed in one of the participating European countries is reported to TESSy as quickly as possible. If other cases are found to have been associated with the same accommodation site within two years, a cluster is identified. Cases of Legionnaires’ disease diagnosed in European citizens outside of the ELDSNet Member States may also be reported to ECDC and trigger a cluster identification in TESSy.

Follow-up of travel-associated clusters
Clusters of travel-associated Legionnaires’ disease are immediately notified to the network. If the country where the accommodation site is located is an ELDSNet Member State, the ELDSNet epidemiologist in that country is requested to report to ECDC within a certain deadline whether any local site risk assessments and precautionary control measures have been taken. If this timeline for reporting is not fulfilled or control measures stated are unsatisfactory, the accommodation site name is published in the ELDSNet online accommodation site list. All sites published here are also notified to the International Federation of Tour Operators.

If the country of infection is not an ELDSNet Member State, ELDSNet reports the cluster to  the World Health Organisation (WHO) which is requested to subsequently inform the Ministry of Health of the country concerned. ECDC welcomes any feedback on subsequent public health interventions, but does not publish any accommodation site names if such information is not received. All clusters outside the ELDSNet Member States, however, are notified to the International Federation of Tour Operators.

Laboratory activities
Since April 2010, ELDSNet is supported in laboratory activities through contracted services by the Health Protection Agency Centre for Infections in London, United Kingdom. The agreed work packages are:

• Method standardisation and training.
• External quality assurance schemes for urinary antigen testing, detection of Legionella species in water, molecular typing of Legionella pneumophila, and detection by PCR.
• Support for investigations of travel-associated clusters of Legionnaires’ disease and of a limited number of community clusters.
• Scientific advice for ECDC.

Laboratory protocols are available for ELDSNet members in the ELDSNet extranet workspace.