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Update on epidemiological investigation into case of Legionnaires' disease

     The Centre for Health Protection (CHP) of the Department of Health today (May 4) reported the latest findings of the epidemiological investigation into a case of Legionnaires' disease (LD) affecting a man aged 60 announced on April 21.

     The patient was admitted to Hong Kong Baptist Hospital (HKBH) on April 5 for his underlying illness. He developed fever and a productive cough on April 15 and was transferred to another private hospital on April 20 for further management. He was transferred to the Intensive Care Unit on April 23 and is now in a stable condition. He had no travel history during the incubation period.

     "In relation to investigation for the possible source of infection, water and environment samples were collected from HKBH and his residence for testing of Legionella, the bacteria causing LD, during our joint epidemiological and environment investigations with the Electrical and Mechanical Services Department (EMSD). The CHP again conducted a site visit to HKBH today and advised on the disinfection of the relevant water system. As precautionary measures, the CHP has recommended HKBH to install filters to the shower heads of the affected ward, and to provide boiled water for in-patients' drinking and mouth rinsing as infection control," a spokesman for the CHP said.

     Upon testing by the CHP's Public Health Laboratory Services Branch (PHLSB), four out of 10 pairs of water samples taken in HKBH tested positive for Legionella pneumophila serogroup 1 (Lp1) with a level from 0.3 to 2.3 colony-forming units per millilitre (cfu/ml). The other water samples including from the fresh water tank were negative for Lp1. In addition, three out of five environment swabs collected from HKBH also tested positive for Lp1.

     All eight pairs of water samples and four environment swabs collected from the patient's residence tested negative for Lp1.

     "As Legionella can be found in various environment settings and aqueous environments, a causal relationship between the case and the laboratory findings cannot be established at this juncture. Testing of the patient's respiratory specimen for Legionella is being performed by the PHLSB. Further laboratory investigation, including genetic characterisation, will be undertaken to ascertain the source of infection as far as possible," the spokesman remarked.

     "We have enhanced medical surveillance in collaboration with HKBH in the ward to which the patient was earlier admitted. No additional cases have been identified thus far. We will maintain close liaison with HKBH to monitor the latest developments," the spokesman said.

     Investigations are ongoing.

     Legionella are found in various environment settings and grow well in warm water (25 to 40 degrees Celsius). They can be found in moist environments such as water tanks, cooling towers, whirlpools and spas, water fountains and apparatus that support breathing. Proper design, operation and maintenance of man-made water systems can prevent LD.

     The public may visit the websites below for more information:

* The CHP's LD page (; and
* The EMSD's Code of Practice for Prevention of LD

Ends/Monday, May 4, 2015
Issued at HKT 19:15


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