Medical Journal of Malaysia

MJM, Vol 70 Supplement 1 September 2015

An outbreak of Legionellosis at a business centre in Kuala Lumpur, 2013

Rohani I*, Normah S*, Nurul Hafizah MY*, Norhaida U**, Ummi Kalthum S*, Balachandran S*

*Kuala Lumpur Federal Territory State Health Department, **Muar District Health Office, Johor


Introduction: Legionnaires’ disease was first described by Fraser et al. following an outbreak of pneumonia among the participants of the American Legion Convention in Philadelphia in 1976. It is caused by Legionella pneumophila, which is commonly found in aquatic environments. On 12th April 2013, Federal Territory State Health Department received notification of two cases working in the same office that were admitted into private hospital with similar respiratory symptoms. Investigation started immediately to identify the causative agents, source of outbreak and to recommend preventive and control measures.

Methods: A cohort study was conducted to identify the risk factors. Active case detection was carried out. All workers of the business centre were interviewed regarding the respiratory symptoms. Clinical samples were taken from workers with respiratory symptoms.

Results: A total of 1,365 workers were examined and 382 were defined as cases (attack rate 27.9%). Blood samples revealed 70 out of 188 (37.2%) samples were positive for IgM Legionella. The business centre was located in the middle of four high storey blocks. The cooling tower used a cross flow system and located at the rooftop of the block. Water samples from the cooling tower and fountain pool was positive for Legionella pneumophila Serogroup 1 and 2.

Conclusion: This Legionella outbreak was due to contaminated cooling tower system and fountain pool. The cooling tower was manually cleaned and tested negative post cleaning. The business centre authority was advised to clean the cooling tower and fountain pool regularly.

Keyword: Legionellosis, cooling tower, fountain