OUTBREAK IN NORWAY, 17 CASES, 2 DEATHS

As of 4 September 2001, 17 confirmed cases and 2 probable cases of Legionnaires' disease had been identified in an outbreak on the west coast of Norway, in the city of Stavanger. 2 of the 19 have died. The cases occurred in persons ranging from 30 to 94 years of age -- 16men and 3 women. All the patients had visited a limited area of Stavanger within 10 days of onset of symptoms, which occurred 26 July in the first patient and 1 September in the latest patient. The investigation has focused on an outdoor decorative fountain and several cooling  towers, but a source has not been implicated. Molecular subtyping is underway to compare environmental and clinical isolates. The fountain was shut down and the cooling towers have been disinfected. Source Eurosurveillance Weekly, 6 September  2001, as reported by Preben Aavitsland and Hans Blystad of the National Institute of Public Health, Oslo, Norway, and Jens Holm of the Medical Health Office, Stavanger, Norway.

UPDATE ON NORWAY OUTBREAK

At that time 17 confirmed and 2 probable cases of Legionnaires' disease had been identified, with 2 deaths. A final report on the outbreak, published in the 29 November 2001 issue of Eurosurveillance Weekly, states that 26 confirmed (by urinary antigen) and 2 probable cases were identified. 21 of the 28 patients were men.  7 of the 28 have died, one of which was one of the two probable cases. The age range of the 28 cases was 16 to 94 years, with a mean age of 54. The age range of those who died was 43 to 94 years, with a mean age of 81.  All the patients had been in the same area in the city centre within the incubation period. Legionella pneumophila serogroup 1 was found in water samples collected from the cooling  tower of a hotel where three of the patients had been staying. The outlet of the cooling tower was situated five meters above ground, close to a bus terminal. Nine isolates from patients and five isolates from the cooling tower showed similarities and were different from other known Norwegian Legionella isolates. The report did not indicate that the isolates matched exactly.

 COMPARISON OF BIOCIDES AND DISINFECTION METHODS

Janet Stout, PhD has developed a comparison of biocides for cooling towers
as well as a comparison of disinfection methods for potable water. The work
is posted at http://www.legionella.org/biocides_research1.htm

Background information
can be found in the following two papers:
* Walker JT, Mackerness CW, Mallon D, Makin T, Keevil CW,  Control of
Legionella pneumophila in a hospital water system by chlorine dioxide. J
Industrial Microbiol. 1998, 15(4):384-390.

* Gao Y, McCall EC, Stout JE, Vidic RD, Yu VL.  Monochloramine and
chlorine dioxide as alternative methods for Legionella control.  American
Water Works Assoc. Denver, CO 2000.

The Legionella Prevention Training Course includes a detailed discussion of
various disinfection methods for potable water, including an analysis of
case studies.