Legionnaires' Disease In Surrey - Test Results, UK

Main Category: Water - Air Quality / Agriculture
Also Included In: Infectious Diseases / Bacteria / Viruses
Article Date: 16 Aug 2007 - 3:00 PDT

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This updates our earlier statement of August 9 regarding a reported case of Legionnaires' disease with alleged links to the Institute of Animal Health, Pirbright.

The Health Protection Agency confirmed that results of environmental samples taken at the Institute of Animal Health at Pirbright and from a contractor who worked at the IAH in June and fell ill with Legionnaires' disease show the strains are different. The strain detected by the patient's urine test does not match the strain of Legionella isolated from the water samples taken.

Typing the strain of Legionella pneumophila is important because there are many different serogroups and several subtypes within each serogroup, especially for serogroup1, the most common cause of human infection. There are subtypes in the environment that do not usually cause infection in humans and if these can be differentiated from the subtypes identified in patient specimens they can be ruled out as being the source of the patient's illness. The finding for this particular case is that the environmental and clinical subtypes are different from each other.

Discussions with the IAH occupational health department, undertaken as a precaution and matter of routine in such investigations, confirm that there are no other reports from employees of unusual symptoms that could be linked to Legionnaires' disease.

The HPA is continuing to investigate the possible source of the infection which caused the contractor's illness. This includes, in line with national guidelines, assessment of everywhere the patient has been 10 to 14 days before falling ill including their home, place of work and anywhere they may have travelled to or visited.

1. Serogrouping is a common method of distinguishing between bacteria based on the presence or absence of certain components of the bacterium's surface.

2. There are 16 serogroups of Legionella pneumophila. Serogroup 1 is the most common cause of infection in humans and accounts for almost all the cases reported to the HPA national surveillance scheme for Legionnaires' disease in residents of England and Wales. Serogroup 1 can be further divided into subtypes and it is these that can be classified into those that cause infection and those that do not usually cause infection.

http://www.hpa.org.uk

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