Legionnaires' disease outbreak investigation toolbox

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The first identified outbreak of Legionnaires' disease occurred in 1976 [1]. Since then there have been many outbreaks of the disease, each with its own unique properties. Reflections on these historical outbreaks are useful resources to inform the response to a new outbreak. For example, Legionella outbreaks can manifest themselves in a range of sizes, from over one hundred cases; e.g. in Murcia [2], Japanese bath house [3] , Dutch flower show [4], Barrow [5], Melbourne [6] and Catalonia [7], to less than twenty in Virginia [8], Victoria [9], Rome [10], Portugal [11] UK [12] and a cruise liner [13]. A large number of outbreaks occur in an outdoor setting and are the result of legionella-contaminated aerosol releases by poorly maintained cooling towers [2; 7; 14-18]. It is important that the source of these outbreaks is found quickly and action taken to remove the bacteria since, given the right meteorological conditions, they have the potential to infect a large number of people. In the Pas-de-Calais outbreak in 2004, cases were found at over 6km from the cooling tower responsible [17]. This outbreak highlights the importance of effectively treating a contaminated system, since a second spike in the epidemic curve occurred, caused by an inefficient cleaning process which failed to prevent the release of bacteria into the atmosphere.

As well as these cooling tower releases, other outbreaks have occurred at particular events [4; 11; 19] or attractions [3; 6] in which the cases were at the source of infection only once. The types of sources involved can vary e.g. fountains [11], spa pools [4; 13]) and wet air conditioning systems [5; 20], and many of these larger outbreaks are summarised and analysed in [21].

Legionnaires' disease has also recently been linked to potting compost bought at garden centres [22] and to manholes [23]. Additionally, outbreaks have been known to occur within, or near, hospitals [14; 20] which is potentially more of a concern since some of the cases are likely to be immuno-compromised,making them more susceptible to infection and death.

Outbreak and clusters that have had some epidemiological investigation are listed here and more specfically with geographic information systems (GIS), either to detect an outbreak from surveillance data or inform the response, are discussed here

Report Citation Location No. of cases (including possible cases where applicable) Source Serogroup 1 subgroup
Edmond-Smith, 2006 [1] Barrow, UK 494 Air conditioning plant Benidorm
Garcia, 2003 [2] Murcia, Spain 449 Cooling tower Pontiac
Sasaki, 2008 [3] Miyazaki, Japan 295 Public bathhouse
Den Boer, 1999 [4] Bovenkarspel, Netherlands 188 Whirlpool spa
Fraser, 1977 [5] Philadelphia, US 182 Hotel lobby
Castilla, 2008 [6] Pamplona, Spain 146 Cooling tower Pontiac
Greig, 2000 [7] Melbourne, Australia 125 Cooling tower Pontiac
Sabria, 2006 [8] Cerdanyola, Spain 113 Cooling tower
Castellani, 1997 [9] Genova, Italy 98 Cooling tower Pontiac
De Schrijver, 2003 [10] Kapellen, Belgium 93 Whirlpool spa
Nguyen, 2006 [11] Pas-de-Calais, France 86 Cooling tower Lens
Klaucke, 1984 [12] Burlington, USA 85 Cooling tower
Henry, 2005 [13] Toronto, Canada 82 Cooling tower
O'Mahony, 1990 [14] Stafford, UK 68 Air conditioning plant Pontiac
Von Baum, 2010 [15] Ulm, Germany 65 Cooling tower Knoxville
Nordstrom, 1983 [16] Vasteras, Sweden 58 Cooling tower
Nygard, 2008 [17] Sarpsborg, Norway 56 Air scrubber
Sala, 2007 [18] Vic-Gurb, Spain 55 Cooling tower
Jansa, 2002 [19] Barcelona, Spain 54 Cooling tower Pontiac
Dondero, 1980 [20] Memphis, USA 47 Cooling tower
Watson, 1994 [21] London, UK 43 Cooling tower Benidorm
Garcia de Olalla, 2008[22] Barcelona, Spain 33 Cooling tower Pontiac
Mahoney, 1992 [23] Bogalusa, USA 33 Mist machine Philadelphia
Glasgow, 1986 [24] Glasgow, UK 33 Cooling tower
Darelid, 1994 [25] Varnamo, Sweden 31 Shower nozzels Benidorm
Sonder, 2008 [26] Amsterdam, Netherlands 31 Cooling tower
Alonso, 2004 [27] Zaragoza, Spain 30 Cooling tower Pontiac
Hugosson, 2007 [28] Lidkoping, Sweden 30 Cooling tower Benidorm
Brown, 1999 [29] Delaware, US 29 Cooling tower Philadelphia
Addiss, 1989 [30] Sheboygan, US 29 Cooling tower Philadelphia
Luna, 2005 [31] Torrevieja, Spain 28 Cooling tower
Blystad, 2001 [32] Stavangar, Norway 28 Cooling tower
Kirrage, 2007 [33] Hereford, UK 28 Cooling tower
Benkel, 2000 [34] Christiansburg, US 23 Whirpool spa Philadelphia
Fiore, 1998 [35] Franklin County, US 22 Cooling tower Philadelphia
Formica, 2000 [36] Thomastown, Australia 18 Cooling tower
O'Loughlin, 2007 [37] Rapid City, US 18 Decorative fountain Benidorm
Garbe, 1985 [38] Rhode Island, US 15 Cooling tower Philadelphia
Rota, 2005 [39] Rome, Italy 15 Cooling tower Philadelphia
Hunt, 1991 [40] Gloucester, UK 14 Cooling tower Pontiac
Correia, 2001 [41] Braga, Portugal 11 Decorative fountain

Reference List

  1. EDMOND-SMITH J. (2006) Report of the public meetings into the Legionella outbreak in Barrow-in-Furness, August 2002 Health and Safety Executive http pdf
  2. GARCIA-FULGUEIRAS A., NAVARRO C., FENOLL D., GARCIA J., GONZALEZ-DIEGO P., JIMENEZ-BUNUALES T., RODRIGUEZ M., LOPEZ R., PACHECO F., RUIZ J., SEGOVIA M., BALADRON B. & PELAZ C. (2003) Legionnaires' disease outbreak in Murcia, Spain Emerging Infectious Diseases 9(8), pp.915 - 921 http pdf
  3. SASAKI T., MATSUMOTO N., NAKAO H., KATOH T., FUKUDA Y., NAKAZATO M. & OKAYAMA A. (2008) An outbreak of Legionnaires' disease associated with a circulating bathwater system at a public bathhouse. I: a clinical analysis. Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases 14, pp.117 - 122 http
  4. DEN BOER J. W, YZERMAN P. F.E., SCHELLEKENS J., LETTINGA K. D, BOSHUIZEN H. C, VAN STEENBERGEN J. E, BOSMAN A., VAN DEN HOF S., VAN VLIET H. A, PEETERS M. F., VAN KETEL R. J., SPEELMAN P., KOOL J.L., & CONYN VAN SPAENDONCK M. A. E. (2002) A large outbreak of Legionnaires' disease at a flower show, the Netherlands, 1999 Emerging Infectious Diseases 8(1), pp.37-43 http pdf
  5. FRASER D. W., TSAI T. R., ORENSTEIN W., PARKIN W. E., BEECHAM H. J., SHARRAR R. G., HARRIS J., MALLISON G. F., MARTIN S. M., MCDADE J. E., SHEPARD C. C. & BRACHMAN P. S. (1977) Legionnaires' disease: description of an epidemic of pneumonia The New England Journal of Medicine 297, pp.1189 - 1197 http pdf
  6. CASTILLA J., BARRICARTE A., ALDAZ J., GARCIA CENOZ M., FERRER T., PELAZ C., PINEDA S., BALADRON B., MARTIN I., GONI B., ARATAJO P., CHAMORRO J., LAMEIRO F., TORROBA L., DORRONSORO I., MARTINEZ-ARTOLA V., ESPARZA M. J., GASTAMINZA M. A., FRAILE P. & ALDAZ P. (2008) A large Legionnaires' disease outbreak in Pamplona, Spain: early detection, rapid control and no case fatality Epidemiology and Infection 136, pp.823 - 832 http
  7. GREIG J. E., CARNIE J. A., TALLIS G. F., RYAN N. J., TAN A. G., GORDON I. R., ZWOLAK B., LEYDON J. A., GUEST C. S. & HART W. G. (2004) An outbreak of Legionnaires' disease at the Melbourne Aquarium, April 2000: investigation and case-control studies The Medical Journal of Australia. 180(11), pp.566-572. http
  8. SABRIA M., ALVAREZ J., DOMINGUEZ A., PEDROL A., SAUCA G., SALLERAS L., LOPEZ A., GARCIA-NUNEZ M. A., PARRON I. & BARRUFET M. P. (2006) A community outbreak of Legionnaires' disease: evidence of a cooling tower as the source Clinical Microbiology and Infectious Diseases 12, pp.642-647 http pdf
  9. CASTELLANI PASTORIS M., CICERONI L., LO MONACO R., GOLDONI P., MENTORE B., FLEGO G., CATTANI L., CIARROCCHI S., PINTO A. & VISCA P. (1997) Molecular epidemiology of an outbreak of Legionnaires' disease associated with a cooling tower in Genova-Sestri Ponente, Italy European Journal of Clinical Microbiology and Infectious Diseases 16 (12), pp.883-892. http
  10. DE SCHRIJVER K., DIRVEN K., VAN BOUWEL K., MORTELMANS L., VAN ROSSOM P., DE BEUKELAAR T., VAEL C., FAJO M., RONVEAUX O., PEETERS M. F., VAN DER ZEE A., BERGMANS A., IEVEN M. & GOOSSENS H. (2003) An outbreak of Legionnaire's disease among visitors to a fair in Belgium in 1999 Journal of the Royal Institute of Public Health 117, pp.117 - 124 http
  11. NGUYEN T. M. N., ILEF D., JARRAUD S., ROUIL L., CAMPESE C., CHE D., HAEGHEBAERT S., GANIAYRE F., MARCEL F., ETIENNE J. & DESENCLOS J.C. (2006) A community-wide outbreak of Legionnaires' disease linked to industrial cooling towers: How far can contaminated aerosols spread? Journal of Infectious Diseases 193, pp.102-111 http
  12. KLAUCKE D. N., VOGT R. L., LARUE D., WITHERELL L. E., ORCIARI L. A., SPITALNY K. C., PELLETIER R., CHERRY W. B. & NOVICK L. F. (1984) Legionnaires' disease: the epidemiology of two outbreaks in Burlington, Vermont, 1980 American Journal of Epidemiology 119(3) pp. 382-391 http
  13. HENRY B., YOUNG J. G. & WALKER D. (2005) Report of the expert panel on the Legionnaires' disease outbreak in the City of Toronto - September/October 2005
  14. O'MAHONY M. C., STANWELL-SMITH R. E., TILLETT H. E., HARPER D., HUTCHINSON J. G. P., FARRELL I. D., HUTCHINSON D. N., LEE J. V., DENNIS P. J., DUGGAL H. V., SCULLY J. A. & DENNE C. (1990) The Stafford outbreak of Legionnaires' disease Epidemiology and Infection 104, pp.361 - 380 http
  15. VON BAUM H., HÄRTER G., ESSIG A., LÜCK C., GONSER T., EMBACHER A. & BROCKMANN S. (2010) Preliminary report: outbreak of Legionnaires' disease in the cities of Ulm and Neu-Ulm in Germany, December 2009 - January 2010 Eurosurveillance 15(4) http
  16. NORDSTRÖM K, KALLINGS I, DAHNSJÖ H. & CLEMENS F. (1983) An outbreak of Legionnaires' disease in Sweden: report of sixty-eight cases Scandinavian Journal of Infectious Disease 15(1), pp.43-55. http
  17. NYGARD K., WERNER-JOHANSEN O., RONSEN S., CAUGANT D. A., SIMONSEN O., KANESTROM A., ASK E., RINGSTAD J., ODEGARD R., JENSEN T., KROGH T., HOIBY E. A., RAGNHILDSTVEIT E., AABERGE I. S. & AAVITSLAND P. (2008) An outbreak of Legionnaires' disease caused by long-distance spread from an industrial air scrubber in Sarpsborg, Norway Clinical Infectious Diseases 46(1), pp.61-69 http
  18. SALA M. R., ARIAS C., OLIVA J. M., PEDROL A., ROURA P. & DOMÍNGUEZ A. (2007) Community outbreak of Legionnaires' disease in Vic-Gurb, Spain in October and November 2005 Eurosurveillance 12(3) pp. 48-50 http
  19. JANSÀ, J.M., CAYLÀ, J.A., FERRER D., GRACIA J., PELAZ C., SALVADOR M., BENAVIDES A., PELLICER T., RODRIGUEZ P., GARCÉS, J.MA., SEGURA A., GUIX J., PLASENCIA A., ARMENGOU J.MA., BOTIA A., MORENO B., FERRER A., GARCÍA DE OLALLA P., GUIX J., PAÑELLA H., PEDRO R., SANZ M., VILLALBÍ RAMÓN, J., DÍEZ A., GARCÍA-CARASUSAN M., MANZANERA R., BENEYTO V., MASDÉU, J., GARRIGA R., DOMÍNGUEZ A., SALLERAS L., ALVAREZ J., BRAVO C., FLORES J., GUDIOL F., GRAU R., MATIA L., MONTERDE R., MORELL F., OROMÍ, J., SABRIÀ, M., TRILLA A. & VAQUÉ, J (2002) An outbreak of Legionnaires' disease in an inner city district: Importance of the first 24 hours in the investigation International Journal of Tuberculosis and Lung Disease 6(9), pp.831-838 http pdf
  20. DONDERO T.J., J.R., RENDTORFF R.C., MALLISON G.F., WEEKS R.M., LEVY J.S., WONG E.W., SCHAFFNER W. (1980) An outbreak of Legionnaires' Disease associated with a contaminated air-conditioning cooling tower The New England Journal of Medicine. 302(7), pp.365-370 http pdf
  21. WATSON J. M., MITCHELL E., GABBAY J., MAGUIRE H., BOYLE M., BRUCE J., TOMLINSON M., LEE J. V., HARRISON T. G., UTTLEY A., O'MAHONY M. C., & CUNNINGHAM D. (1994) Piccadilly Circus Legionnaires' disease outbreak Journal of Public Health Medicine 16 (3), pp. 341-347. http
  22. GARCÍA DE OLALLA P., GRACIA J., RIUS C., CAYLÀ J.A., PAÑELLA H., VILLABÍ J.R., GUIX J., PELLICER T., FERRER D., CUSI M., PELAZ C. & SABRIÀ M. (2008) Community outbreak of pneumonia due to Legionella pneumophila: importance of monitoring hospital cooling towers Enfermedades infecciosas y microbiologia clinica. 26(1) pp.15-22 http
  23. MAHONEY F J, HOGE C W, FARLEY T A, BARBAREE J M, BREIMAN R F, BENSON R F, MCFARLAND L M, (1992) Communitywide outbreak of Legionnaires' disease associated with a grocery store mist machine Journal of Infectious Diseases 165(4), pp.736-9 http
  24. (1986) Outbreak of Legionellosis in a Community. Report of an ad-hoc committee Lancet (2) (8503) pp.380-383. http
  25. DARELID J., BENGTSSON L., GÄSTRIN B., HALLANDER H., LÖFGREN S., MALMVALL B. E., OLINDER-NIELSEN A M. & THELIN A. C. (1994) An outbreak of Legionnaires' disease in a Swedish hospital Scandinavian Journal of Infectious Diseases 26(4), pp.417-25 http
  26. SONDER G. J., VAN DEN HOEK J. A., BOVÉE L. P., AANHANE F. E., WORP J., DU RY VAN BEEST HOLLE M., VAN STEENBERGEN J. E., DEN BOER J. W. & IJZERMAN E. P. COUTINHO R A, (2008) Changes in prevention and outbreak management of Legionnaires' disease in the Netherlands between two large outbreaks in 1999 and 2006 Eurosurveillance 13, (38) http
  27. ALONSO J.P. (2004) Community outbreak of Legionnaires' disease related to hospital cooling towers in Zaragoza, Spain, May-June 2004 Eurosurveillance 8(33) http
  28. HUGOSSON A., HJORTH M., BERNANDER S., CLAESSON B. E. B, JOHANSSON A., LARSSON H., NOLSKOG P., PAP J., SVENSSON . & ULLERYD P. (2007) A community outbreak of Legionnaires' disease from an industrial cooling tower: assessment of clinical features and diagnostic procedures Scandinavian Journal of Infectious Diseases 39(3), pp.217-224. http
  29. BROWN C. M., NUORTI P. J., BREIMAN R. F., HATHCOCK A. L., FIELDS B. S., LIPMAN H. B., LLEWELLYN G. C., HOFMANN J. & CETRON M. (1999) A community outbreak of Legionnaires' disease linked to hospital cooling towers: An epidemiological method to calculate dose of exposure International Journal of Epidemiology 28, pp.353-359 http pdf
  30. ADDISS D.G., DAVIS J.P., LAVENTURE M., WAND P.J., HUTCHINSON M.A., & MCKINNEY R.M. (1989) Community-acquired Legionnaires' disease associated with a cooling tower: evidence for longer-distance transport of Legionella pneumophila American Journal of Epidemiology 130(3), pp.557 - 568 http
  31. LUNA H. V., ALEDON R. M., MORAN F. G. & RODRIGO S. G. (2005) Outbreak of legionnaires' disease in Torrevieja, Spain, November-December 2005 Eurosurveillance 10(51) http
  32. BLYSTAD HANS, BRANTSAETER ARNE BROCH, LOVOLL ØISTEIN, (2005) Outbreak of community-acquired Legionnaires' disease in southeast Norway, May 2005 Eurosurveillance 10 (21) http
  33. KIRRAGE D., REYNOLDS G., SMITH G.E. & OLOWOKURE B; HEREFORD LEGIONNAIRES' OUTBREAK CONTROL TEAM (2007) Investigation of an outbreak of Legionnaires' disease: Hereford, UK 2003 Respiratory Medicine 101(8), pp.1639-1644 http
  34. BENKEL D. H., MCCLURE E. W., WOOLARD D., RULLAN J. V., MILLER JR G. B., JENKINS S. R., HERSHEY R. L., BETTY S. R. & BRIEMAN R. F. (2000) Outbreak of Legionnaires' disease associated with a display whirlpool spa International Journal of Epidemiology 29(6), pp. 1092 - 1098 http pdf
  35. FIORE A. E., NUORTI J. P., LEVINE O. S., MARX A., WELTMAN A. C., YEAGER S., BENSON R. F., PRUCKLER J., EDELSTEIN P. H., GREER P., ZAKI S. R., FIELDS B. S. & BUTLER J. C. (1998) Epidemic Legionnaires' disease two decades later: old sources, new diagnostic methods Clinical Infectious Diseases 26(2):426-33 http
  36. FORMICA N., TALLIS G. F., ZWOLAK B., CARNIE J. A., BEERS M., HOGG G., RYAN N. J. & YATES M. (2000) Legionnaires' disease outbreak: Victoria's largest identified outbreak Communicable Diseases Intelligence 24(7), pp.199 - 202 http pdf
  37. O'LOUGHLIN R.E., KIGHTLINGER L., WERPY M. C., BROWN E., STEVENS V., HEPPER C., KEANE T., BENSON R.F., FIELDS B.S. & MOORE M.R. (2007) Restaurant outbreak of Legionnaires' disease associated with a decorative fountain: an environmental and case-control study BMC Infectious Diseases http://www.biomedcentral.com/1471-2334/7/93. 7:93 http pdf
  38. GARBE P. L., DAVIS B. J., WEISFELD J. S., MARKOWITZ L., MINER P., GARRITY F., BARBAREE J .M. & REINGOLD A. L. (1985) Nosocomial Legionnaires' disease. Epidemiologic demonstration of cooling towers as a source The Journal of the American Medical Association 254(4), pp.521-524 http
  39. ROTA M.C., PONTRELLI G., SCATURRO M., BELLA A., BELLOMO A.R., TRINITO M.O., SALMASO S. & RICCI M.L (2005) Legionnaires' disease outbreak in Rome, Italy Epidemiology and Infection 133 (5), pp. 853-859. http
  40. HUNT D. A., CARTWRIGHT K. A. V., SMITH M. C., MIDDLETON J., BARTLETT C. L. R., LEE J. V., DENNIS P. J. & HARPER D. (1991) An outbreak of Legionnaires' disease in Gloucester Epidemiology and Infection 107, pp.133 - 141 http
  41. CORREIA A. M., GONCALVES G., REIS J., CRUZ J. M. & CASTRO E FREITAS J. A. (2001) An outbreak of Legionnaires' disease in a municipality in northern Portugal Eurosurveillance 6(7), pp.21-24. http