Um grande surto da Doença dos Legionários numa cidade industrial em Portugal

Translated title of the contribution: A large outbreak of Legionnaires’ Disease in an industrial town in Portugal

Francisco George, Tara Shivaji, Catia Sousa Pinto, Luis Antonio Oliveira Serra, João Valente, Maria João Albuquerque, Paula Cristina Olivença Vicêncio, Ana San-Bento, Paulo Diegues, Paulo Jorge Nogueira, Teresa Marques, Helena Rebelo, Filipa Costa, Raquel Rodrigues, Alexandra Nunes, Vitor Borges, João Paulo Gomes, Daniel Sampaio, Paula Barreiro, Silvia DuarteDina Carpinteiro, Joana Mendonça, Catarina Silva, Luís Vieira, Maria Joao Simões, Paulo Gonçalves, Baltazar Nunes, Carlos Dias, Jorge Machado, Fernando Almeida, Elsa A. Goncalves, Lucilia Carvalho, Pedro Viterbo, Dilia Jardim, Nuno Lacasta, Filomena Boavida, Ana Perez, Isabel Santana, Paula Matias, Nuno Banza, Carlos Rabacal

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)
43 Downloads (Pure)


Background We describe the investigation and control of an outbreak of Legionnaires’ disease in Portugal in October, November and December 2014. Methods Confirmed cases were individuals with pneumonia, laboratory evidence of Legionella pneumophila serogroup 1 and exposure, by residence, occupational or leisure to the affected municipalities. 49 possible sources were reduced to four potential sources, all industries with wet cooling system, following risk assessment. We geo-referenced cases’ residences and the location of cooling towers defining four study areas 10 km buffer centered on each cooling tower system. We compared the number of cases with expected numbers, calculated from the outbreak's attack rates applied to 2011 census population. Using Stones’ Test, we tested observed to expected ratios for decline in risk, with distance up to 10 km four directions. Isolates of Legionella pneumophila were compared using molecular methods. Results We identified 403 cases, 377 of which were confirmed, 14 patients died. Patients became ill between 14 October and 2 December. A NE wind and thermal inversion were recorded during the estimated period of exposure. Disease risk was highest in people living south west from all of the industries identified and decreased with distance (p < 0.001). 71 clinical isolates demonstrated an identical SBT profile to an isolate from a cooling tower. Whole genome sequencing identified an unusual L. pneumophila subsp. fraseri serogroup 1 as the outbreak causative strain, and confirmed isolates’ relatedness. Conclusions Industrial wet cooling systems, bacteria with enhanced survival characteristics and a combination of climatic conditions contributed to the second largest outbreak of Legionnaires’ disease recorded internationally.

Translated title of the contributionA large outbreak of Legionnaires’ Disease in an industrial town in Portugal
Original languagePortuguese
Pages (from-to)199-208
Number of pages10
JournalRevista Portuguesa de Saúde Pública
Issue number3
Publication statusPublished - 1 Sept 2016


  • Legionella pneumophila fraseri
  • Legionnaires’ disease


Dive into the research topics of 'A large outbreak of Legionnaires’ Disease in an industrial town in Portugal'. Together they form a unique fingerprint.

Cite this