European Working Group For Legionella Infections Research Articles

Presence and Persistence of Viable, Clinically Relevant Legionella pneumophila Bacteria in Garden Soil in the Netherlands.

ABSTRACTGarden soils were investigated as reservoirs and potential sources of pathogenic Legionella bacteria. Legionella bacteria were detected in 22 of 177 garden soil samples (12%) by amoebal coculture. Of these 22 Legionella-positive soil samples, seven contained Legionella pneumophila. Several other species were found, including the pathogenic Legionella longbeachae (4 gardens) and Legionella sainthelensi (9 gardens). The L. pneumophila isolates comprised 15 different sequence types (STs), and eight of these STs were previously isolated from patients according to the European Working Group for Legionella Infections (EWGLI) database. Six gardens that were found to be positive for L. pneumophila were resampled after several months, and in three gardens, L. pneumophila was again isolated. One of these gardens was resampled four times throughout the year and was found to be positive for L. pneumophila on all occasions. IMPORTANCE Tracking the source of infection for sporadic cases of Legionnaires' disease (LD) has proven to be hard. L. pneumophila ST47, the sequence type that is most frequently isolated from LD patients in the Netherlands, is rarely found in potential environmental sources. As L. pneumophila ST47 was previously isolated from a garden soil sample during an outbreak investigation, garden soils were investigated as reservoirs and potential sources of pathogenic Legionella bacteria. The detection of viable, clinically relevant Legionella strains indicates that garden soil is a potential source of Legionella bacteria, and future research should assess the public health implication of the presence of L. pneumophila in garden soil.

Genotypic diversity of Legionella pneumophila in environmental and clinical strains assessed by Sequence-Based Typing, in association with retrospective clinical surveillance in Northern Italy.

The study aimed to evidence previous cases of legionellosis or proven or suspected pneumonia in seven hospital facilities for the mentally disabled in Northern Italy, where no clinical surveillance had been previously carried out. An additional aim was to highlight the occurrence of strains of Legionella pneumophila of clinical and environmental origin by Sequence-Based Typing (SBT), comparing them to world surveillance. A clinical survey was perfomed from 2003-2012, analyzing 615 medical records for hospital- and community-acquired pneumonia, with particular attention to legionellosis. Clinical (n=4) and environmental (n=25) isolates of Legionella pneumophila, isolated in the same period (2003-2012), were characterized by SBT and the Sequence Types (STs) compared with the European Working Group for Legionella Infections (EWGLI) database. Surveillance revealed that there were seven detected cases of legionellosis; most pneumonia cases could not be confirmed by diagnostic tests because of the disabilities of the patients and their lack of cooperation. The same ST was found in two of the clinical strains and also in a corresponding environment, i.e. ST685 and ST16, and two clinical strains belonging to the same ST (ST1). The other environmental strains were isolated in department with confirmed/suspected clinical cases. Five other STs found in this study were new to the database: ST685 was isolated both from a patient and from water; ST694, ST1181, ST1370 and ST1371 have not been described previously. The study confirmed that the routine collection and analysis of environmental strains may be an important strategy for preventing sporadic and epidemic cases of legionellosis, in association with clinical surveillance.

Environmental surveillance and molecular epidemiology of waterborne pathogen Legionella pneumophila in health-care facilities of Northeastern Greece: a 4-year survey.

A 4-year proactive environmental surveillance of Legionella spp. in the water distribution and cooling systems of five health-care facilities was carried out as part of the strategy for the prevention of hospital-acquired Legionnaires' disease in Northeastern Greece. Legionella spp. were detected in 71 out of 458 collected samples. The majority of strains belonged to Legionella pneumophila serogroups 2-15 (75.0%), while all L. pneumophila serogroup 1 strains (23.6%) were isolated from a single hospital. The highest percentage of positive samples was found in distal sites (19.4%), while no Legionella strains were detected in cooling systems. Each hospital was colonized at least once with L. pneumophila, while remedial actions resulted in significant reduction of Legionella concentration. The molecular epidemiology of environmental L. pneumophila strains was also investigated using random amplified polymorphic DNA (RAPD) and multi-gene sequence-based analysis. Based on RAPD patterns, L. pneumophila serogroups 2-15 and serogroup 1 strains were classified into 24 and 9 operational taxonomic units (OTUs), respectively. Sequencing of housekeeping and diversifying pressure-related genes recommended by European Working Group for Legionella Infections (EWGLI) revealed not only a high intraspecies variability but also the circulation and persistence of one specific genotyping profile in the majority of hospitals. This study highlights the necessity for diachronic surveillance of Legionella in health-care facilities by adopting both cultural and molecular methods.

Legionella detection and subgrouping in water air-conditioning cooling tower systems in Kuwait.

The main aim of the study was to test for the presence of Legionnaires' disease-causing microorganisms in air-conditioned buildings in Kuwait using molecular technologies. For this purpose, 547 samples were collected from 38 cooling towers for the analysis of Legionella pneumophila. These samples included those from water (n = 178), air (n = 231), and swabs (n = 138). Out of the 547 samples, 226 (41%) samples were presumptive positive for L. pneumophila, with L. pneumophila viable counts in the positive water samples ranging from 1 to 88 CFU/ml. Of the Legionella culture-positive samples, 204 isolates were examined by latex agglutination. These isolates were predominately identified as L. pneumophila serogroup (sg) 2-14. Using the Dresden panel of monoclonal antibodies, 74 representatives isolates were further serogrouped. Results showed that 51% of the isolates belonged to serogroup 7 followed by 1 (18%) and 3 (18%). Serogroups 4 (4%) and 10 (7%) were isolated at a lower frequency, and two isolates could not be assigned to a serogroup. These results indicate the wide prevalence of L. pneumophila serogroup 7 as the predominant serogroup at the selected sampling sites. Furthermore, the 74 L. pneumophila (sg1 = 13; sg3 = 13; sg4 = 3; sg7 = 38; sg10 = 5; sgX = 2) isolates were genotyped using the seven gene protocol sequence-based typing (SBT) scheme developed by the European Working Group for Legionella Infections (EWGLI). The results show that Legionella isolates were discriminated into nine distinct sequence typing (ST) profiles, five of which were new to the SBT database of EWGLI. Additionally, all of the ST1 serogroup 1 isolates were of the OLDA/Oxford subgroup. These baseline data will form the basis for the development of a Legionella environmental surveillance program and used for future epidemiological investigations.

Molecular epidemiology of Legionella pneumophila serogroup 1 isolates identify a prevalent sequence type, ST505, and a distinct clonal group of clinical isolates in Toyama Prefecture, Japan

We performed comparative analyses of Legionella pneumophila serogroup (SG) 1 isolates obtained during 2005-2012 in Toyama Prefecture, Japan, by sequence-based typing (SBT) and pulsed-field gel electrophoresis (PFGE). Seventy-three isolates of L. pneumophila SG 1, including 17 isolates from patients, 51 from public baths, 4 from cooling towers, and 1 from a shower, were analyzed. The isolates were classified into 43 sequence types (STs) by SBT and 52 types by PFGE. Fourteen STs were unique to Toyama Prefecture, as determined from the SBT database of European Working Group for Legionella Infections (EWGLI), as of October 31, 2012. ST505 strain was identified in 4 isolates from patients and 5 isolates from public baths, and these isolates belonged to 2 PFGE types. These, however, were similar because of the difference with only two restriction fragments, indicating that ST505 strain was prevalent among L. pneumophila SG 1 isolates in this area. ST505 strains isolated from patients and public baths were distributed along the river in a western part of Toyama Prefecture. SBT and PFGE profiles of 3 clinical isolates were identical with those of 3 environmental isolates from the suspected origins of the infection in each case, respectively. This finding suggested that SBT and PFGE were useful for epidemiological study. Furthermore, by SBT analysis, we identified a clonal group formed only by 7 clinical isolates that are not associated with bathwater, suggesting that they were derived from unrecognized sources.

Sequence-based typing of Legionella pneumophila serogroup 1 clinical isolates from Belgium between 2000 and 2010

Sequence-based typing (SBT) is a discriminatory method widely used to genotype Legionella pneumophila strains. A total of 86 clinical L. pneumophila serogroup 1 (sg1) isolates, collected between January 2000 and December 2010 in the two Belgian National Reference Centres for Legionella pneumophila, were genotyped using the internationally standardised SBT protocol of the European Working Group for Legionella Infections (EWGLI). The isolates could be classified into 31 different sequence types (ST, index of diversity: 0.879). The obtained STs were submitted to the EWGLI SBT-database for L. pneumophila. In our study, ST47 (27.9%) and ST1 (19.8%) were the most frequently detected STs. The detected profiles were a combination of both frequently isolated and unique STs, and of both worldwide distributed and more local strains. Two STs, ST880 and ST881, were new to the EWGLI database. In conclusion, we characterised L. pneumophila sg1 isolates with the SBT method, and created a Belgian profile database that will be useful for future epidemiological studies.

Travel-associated Legionnaires’ disease in Europe in 2009

A total of 818 cases of Legionnaires' disease with onset of illness in 2009 were reported from 22 European and two non-European countries to the European Surveillance Scheme for Travel-Associated Legionnaires' Disease (EWGLINET). This is a decrease of 52 cases compared with 2008 and 129 fewer than in 2007 - the peak year of reporting to date. A total of 794 (97.1%) cases were reported as confirmed and 24 as presumptive cases. Outcome of illness was reported for 561 (68.6%) cases. Of these cases 28 (5%) were reported to have died. More than half, of the cases in 2009 (n=469, 57.3%) were reported within 20 days of symptom onset. Cases visited 53 countries and were infected in all months of the year, with a peak in September (n=146). By country of residence of the cases, the United Kingdom (UK) reported the highest number of cases (n=173). Italy reported the second highest number of cases (n=169) and was also the country associated with the most cases by country of infection (n=209). A total of 88 new clusters (75 in Europe and 13 outside Europe) were detected in 2009 and were associated with 196 cases. The largest cluster occurred in Italy and involved seven cases. Without the scheme's international database, thirty three (37.5%) of the newly detected clusters would not have been identified. In 49 of the accommodation sites with clusters of cases, environmental samples were found to be positive for Legionella spp. Details of 10 sites were published on the European Working Group for Legionella Infections (EWGLI) website for failure to return information on the status of environmental investigations.

Distribution of Legionella species from environmental water sources of public facilities and genetic diversity of L. pneumophila serogroup 1 in South Korea.

A total of 560 Legionella species were isolated from environmental water sources from public facilities from June to September 2008 throughout South Korea. The distribution of Legionella isolates was investigated according to geographical region, facility type, and sample type. The genetic diversity of 104 isolates of Legionella pneumophila serogroup 1 (sg 1) was analyzed by sequence-based typing (SBT). L. pneumophila was distributed broadly throughout Korea, accounting for 85.0% of the isolates, and L. pneumophila sg 1 predominated in all of the public facilities except for the springs. Legionella anisa and Legionella bozemanii predominated among non-L. pneumophila species (48.1% and 21.0%, respectively). The second most dominant strain differed depending on the facility type: L. anisa was the second most dominant strain in the buildings (10.8%), L. pneumophila sg 5 in public baths (21.6%), L. pneumophila sg 6 in factories (12.0%), and L. pneumophila sg 7 in hospitals (13.1%). In the SBT analysis, 104 L. pneumophila sg 1 isolates were differentiated into 26 sequence types (STs) and categorized into 3 clonal groups (CGs) and 10 singleton STs via the eBURST V3 program. ST1, a potential founder of major CG1, was commonly distributed (48.1%). The dominant ST in hot water was ST-K1 (7, 12, 17, 3, 35, 11, 11), which was designated in this study (36.1%). The second most dominant strain differed depending on the type of facility from which the samples were obtained. The unique allelic profile of ST-K1, obtained from hot water, was not found in the European Working Group for Legionella Infections (EWGLI) SBT database.

Legionella pneumophila monoclonal antibody subgroups and DNA sequence types isolated in Canada between 1981 and 2009: Laboratory Component of National Surveillance

Legionella pneumophila (Lp) is a significant cause of nosocomial, community-acquired, and travel-associated pneumonia in industrialized regions. Legionellosis has been a nationally notifiable disease in Canada since 1986, with an average of 75 cases reported annually; however, only the most severe, and often fatal, cases are reported or investigated. Here, epidemiological relationships, types, and distribution of Lp referrals to the Canadian national reference center were studied. Lp strains from different years, sources, and geographic locations were subtyped using a sequence-based typing (SBT) scheme and by the 'Joly' and/or 'Dresden' monoclonal antibody panels. Included were 128 epidemiologically unrelated clinical and 86 unrelated environmental strains. Sixty-four (index of diversity [IOD] = 0.964) and 45 (IOD = 0.888) sequence types (STs) were observed among clinical and environmental sources, respectively. Serogroup (sg) 1 was represented by 60.2% (77/128) and 52.3% (45/86) of clinical and environmental strains, respectively, and 63.6% (49/77) and 15.6% (7/45) of those were mAb2-positive, respectively. Serogroup 1, ST1 accounted for 14.1% (18/128) and 30.2% (26/86) of unrelated clinical and environmental isolates, respectively. This database will serve as a basis for Canadian epidemiological surveillance efforts and is linked to global surveillance initiatives curated by the European Working Group for Legionella Infections (EWGLI) network.

Sequence-based and monoclonal antibody typing of Legionella pneumophila isolated from patients in Portugal during 1987-2008

The monoclonal antibodies and the sequence-based typing (SBT) are two methodologies widely used to characterise Legionella pneumophila strains serogroup 1 (sg1). In this study, we analysed the clinical strains received in two Portuguese laboratories since 1987, including the strains isolated in Portugal during the four years of the surveillance scheme for Legionnaires' disease implemented in 2004. In total, 63 clinical isolates of L. pneumophila sg1 were differentiated by SBT into 19 different sequence types. Ten of them were new in the SBT database of the European Working Group for Legionella Infections (EWGLI). As a result of the combination of the two methodologies, these strains were discriminated into 25 different profiles. This study enabled, for the first time in Portugal, not only to characterise the L. pneumophila sg1 clinical isolates, but also to create a database of Portuguese profiles for use in epidemiological surveillance efforts.

Travel-associated Legionnaires’ disease in Europe in 2007

Nine hundred and forty six cases of travel-associated Legionnaires disease were reported to the European Surveillance Scheme for Travel Associated Legionnaires Disease (EWGLINET) with onset during 2007; 890 were confirmed and 56 were presumptive. Twenty eight cases died, giving a case fatality rate of 3.0%. 8.2% of cases were diagnosed by culture, an important increase from 5.2% in 2006. One hundred and twelve new clusters were identified; the largest involved nine cases. Sixteen of these clusters (14.3%) occurred in countries outside EWGLINET, and three involved cruise ships. Twenty nine of the new clusters (25.9%) would not have been detected without the EWGLINET scheme. A total of 151 investigations were conducted in Europe, 42 of which were conducted at re-offending sites (where additional cases had onset after a report was received to say that investigations and control measures had been satisfactorily conducted). The names of 13 accommodation sites were published on the European Working Group for Legionella Infections (EWGLI) website; 11 of these were situated in Turkey.

Distribution of Legionella pneumophila serogroups, monoclonal antibody subgroups and DNA sequence types in recent clinical and environmental isolates from England and Wales (2000–2008)

Clinical isolates of Legionella pneumophila, obtained from 167 patients, who acquired their illness in the community in England and Wales between January 2000 and March 2008, were compared with 276 environmental isolates of L. pneumophila obtained over the same period as part of the routine sampling of 'managed' water systems. The 443 isolates were typed by monoclonal antibody (mAb) subgrouping and the internationally standardised, seven-gene loci, sequence-based typing (SBT) scheme of the European Working Group for Legionella Infections (EWGLI). Of the clinical isolates, 97.6% were L. pneumophila serogroup (sgp) 1, compared with only 55.8% of environmental isolates (P = 0.0002); 91.6% were subgrouped as mAb3/1+ve, compared with only 8.3% of environmental isolates (P < 0.0001). The isolates were very diverse, with SBT identifying 111 sequence types (STs) (index of diversity [IOD] 0.954). Among the clinical isolates, 42 ST were seen, with one (ST47) accounting for 25.7% and three (ST47, ST37 and ST62) accounting for 46.1% of all isolates. Eighty-two STs were identified among the environmental isolates, with two (ST1 and ST79) accounting for 34.1% of these. Comparison of the STs seen among clinical and environmental isolates showed that there was very little overlap between the two populations (P < 0.0001), with common clinical strains found in the environment very infrequently: 0.4, 0.7 and 0% (ST47, ST37 and ST62, respectively), and common environmental strains rarely causing disease: 4.8 and 1.2% (ST1 and ST79, respectively). Combining phenotypic and genotypic data identified 144 phenons (IOD 0.970); 52 among clinical isolates and 101 among environmental isolates. The most abundant clinical strain, mAb 'Allentown' ST47, accounted for 22.8% of cases, but was only found once in the environment. Conversely, mAb 'Oxford/OLDA' ST1 was the most common environmental strain (17.0%), but only caused two infections. A review of the published data shows that mAb 'Allentown' ST47 is also an important cause of infection in France and possibly in the Netherlands. However, it was not found in a large study of German clinical isolates. This study confirms previous work showing that just a few strains of L. pneumophila cause the majority of community-acquired Legionella infection in England and Wales, and that these clinically significant strains are only rarely found in managed water systems. These data suggest that knowing which particular strain is present in an environment might be at least as important as knowing the quantity in which legionellae are present.

Clusters of travel-associated Legionnaires’ disease in Italy, Spain and France, July 2002 - June 2006

For several years, over 50% of the cases of travel-associated Legionnaires' disease (TALD) reported to the European Working Group for Legionella Infections (EWGLINET) have been among travellers to France, Italy, and Spain. We describe clusters of TALD cases reported in these countries during a four-year period. We analysed data from EWGLINET and from the individual countries. In all three countries, upon notification of a cluster, local health authorities are alerted by the national collaborator and immediately begin an environmental investigation at the accommodation site, which includes risk assessments and analysis of water samples. From July 1, 2002 to June 30, 2006, 2,101 accommodation sites were associated with TALD cases and reported by EWGLINET to Italian, Spanish and French collaborators. Of these, 252 sites (12%) were associated with clusters: 13.8% (96/697) in Italy, 13.2% (81/615) in Spain and 9.5% (75/789) in France. Overall, 641 cases were reported. Hotels, camping sites and ships and other sites represented respectively 83%, 10% and 7% of the total accommodation sites, with similar proportions in the three countries. In 99% of the sites, samples were collected; 62% of them were found to be positive for Legionella. The findings of this study highlight that disinfection and long-term preventive measures were correctly implemented by the large majority of sites. However, additional efforts must be made to further reduce the percentage of re-offending sites so as to reduce the number of accommodations that are contaminated by Legionella.

Population structure and recombination in environmental isolates of Legionella pneumophila

Legionella pneumophila is a water-borne bacteria responsible for most cases of legionellosis, an emerging disease with an increasing incidence in industrialized countries. Although early analysis based on multilocus enzyme electrophoresis (MLEE) described the population structure of this species as clonal, more recent reports have suggested that recombination also contributes to shaping variation across its genome. We report here the results of analysing the nucleotide sequences of 19 loci in 31 environmental samples of L. pneumophila from a small Spanish region (near Alcoi, province of Alicante) where legionellosis has become almost endemic. We analysed the six loci currently incorporated to the sequence-based typing scheme developed by European Working Group for Legionella Infections (EWGLI) for L. pneumophila and 13 intergenic regions, for which we developed primers anchored in flanking, conserved genes. Our results show that recombination among natural isolates of this species is a common phenomenon, as 20 of the 31 isolates contained at least one locus in which recombination was revealed by at least three different methods. The mapping of the recombination events on the maximum likelihood tree of the concatenate sequence of the 19 loci indicated that at least nine independent recombination events might explain the observed distribution of recombinant loci among isolates. In consequence, we have shown that recombination in L. pneumophila is much more frequent than previously considered and that it does not seem to be restricted to already described pathogenicity islands or other genome constituents which provide it with a high plasticity.

Legionnaires' Disease and Travel in Europe

To the Editor: The European Working Group for Legionella Infections (EWGLINET) conducts epidemiologic surveillance of Legionnaires' disease cases associated with travel (1) and provides epidemiologic typing markers of Legionella pneumophila among reference laboratories in collaborating countries. The procedures and criteria of notification are found in the Guidelines for Control and Prevention of Travel Associated Legionnaires' Disease (2). However, establishing the association of >1 case of this disease and a specific tourist accommodation site is difficult because of low attack rates and dispersal of people from the source of infection during the incubation period. Collaboration promoted by this working group encourages the exchange of data instead of cultures. This distinction is critical when research is conducted on travel-associated Legionnaires' disease, in which strains from patients and environmental sources of infection studied are in different laboratories. The value of such information is shown in a complex case study that was recently investigated. During July and August 2005, two patients with Legionnaire's disease living in 2 countries in Europe were reported to EWGLINET. Patient 1 was a 45-year-old woman who traveled in France and Spain July 1–6, 2005. Her symptoms started on July 6, 2005, when she was in Girona, Spain, where she was hospitalized. Patient 2 was a 56-year-old woman who traveled in Spain and France August 16–21, 2005. Her symptoms started on August 8, 2005, when she was in France, where she was hospitalized. Both patients tested positive for L. pneumophila serogroup 1 by specific urinary antigen test and culture, but they recovered and were discharged. After routine notification to EWGLINET, it was established from the list of accommodation sites provided by the 2 patients that they each had stayed for 1 night at the same hotel in a French city within a 45-day interval. This finding led us to identify a cluster according to the definition in use (2 cases associated with the same accommodation within 2 years) (2). However, patient 2 spent 1 day in August in Zaragoza, Spain, during which an outbreak of Legionnaires' disease in the city affected 30 persons. Thus, illness in patient 2 could have been associated with the Zaragoza outbreak. Alternatively, both patients could have contracted the illness independently at different sites. Before onset, patient 1 stayed 5 days in her private residence in Girona and patient 2 visited 3 other hotels. As soon as cultures from the 2 patients were available, the National Reference Laboratories of France and Spain shared their respective microbiologic results. Since both strains were identified as L. pneumophila serogroup 1, we performed sequence-based typing (SBT) (3) of 6 genes (flaA, pilE, asd, mip, mompS, and proA) by using the protocol and database of EWGLINET. Both isolates showed identical SBT patterns (2,3,18,15,2,1). Isolates from 4 patients in the Zaragoza outbreak were identified at the Spanish Reference Laboratory as L. pneumophila serogroup 1 (Philadelphia monoclonal antibody type) and had identical SBT patterns (3,4,1,1,14,9). Collaboration between public health authorities in France and Spain enabled us to eliminate the association of patient 2 with the Zaragoza outbreak and establish an association of both patients with the same site in France. Control measures were taken at the hotel, but we could not obtain environmental cultures for comparison with those of the patients. Lack of environmental data prevented investigation of the relationship with the other accommodation sites visited. The SBT method provides robust genotyping with high discriminatory power (index of discrimination >0.94) (3). This method is less effective at discriminating between strains than pulsed-field gel electrophoresis (4), but it shows excellent reproducibility and may be useful in epidemiologic investigation of outbreaks caused by L. pneumophila. The availability of an online database with accessible information is key for sharing results and determining the geographic distribution of isolates that cause Legionnaires' disease (4,5). This study demonstrates the critical role of sharing results between countries that participate in a network. Agreement is essential on a standardized questionnaire that includes more information on the patient's exposure to a disease. Moreover, despite the performance of the urine antigen test, cultures of clinical samples should be encouraged by clinicians and microbiologists. This step would permit use of techniques, such as SBT, in reference laboratories and sharing of results. Our investigation would have been more difficult without this technique in identifying the site where the infection potentially originated.

The impact of new guidelines in Europe for the control and prevention of travel-associated Legionnaires’ disease

On 1 July 2002, EWGLINET introduced European guidelines for the control and prevention of travel-associated legionnaires’ disease. This paper presents the results gathered by the surveillance scheme during the first two and a half years of the operation of the guidelines (to the end of 2004). Two hundred and thirty-seven new clusters and 70 cluster updates were identified. Investigations at 146 sites returned positive samples for legionella, and the proportion of positive sites reached over 60% in 2004. Thirty-four cluster sites were reported to have been investigated satisfactorily, but have gone on to be associated with subsequent cases (‘repeater sites’). Fifty-one sites were published on the European Working Group for Legionella Infections (EWGLI) website; the publication states that EWGLINET cannot be confident that the sites have adequate control measures in place. The operation of the guidelines is discussed, and the situation in Turkey highlighted as a particular success.

Travel associated legionellosis among European tourists in Spain - a comment from the EWGLI coordinating centre

This interesting paper has analysed the data on cases of legionellosis associated with travel to Spain and highlighted some issues which are relevant to the European Working Group for Legionella Infections (EWGLI) surveillance system, eg the reporting of

EWGLI: a European surveillance scheme for travel associated legionnaire s disease.

The European Working Group for Legionella Infections (EWGLI) was set up in 1986 and introduced the European Surveillance Scheme for Travel Associated Legionnaires Disease in 1987. The microbiologists working in reference laborat-ories and the epidemiolog