AN OUTBREAK OF LEGIONNAIRES-DISEASE IN A SWEDISH HOSPITAL

We report a nosocomial outbreak of Legionella pneumophila serogroup (s g) 1 infection at the general hospital, Varnamo, Sweden. From December 1990 to February 1991, 28 patients and 3 staff fell ill with pneumoni a and 3 died. L. pneumophila sg 1 together with several other Legionel lae were isolated from the hot water supply to 17 of 20 hospital wards , probably being spread by aerosolization via shower nozzles. Raising the hospital's hot water temperature from 45 degrees C to 65 degrees C , together with heat disinfection of the shower equipment, arrested th e outbreak within a week. Keeping the hot water temperature greater th an or equal to 60 degrees C without chlorination eliminated L. pneumop hila from > 75% of the wards. During a period of 2 years after the out break we have diagnosed only 1 case of nosocomial legionellosis at the hospital despite an active surveillance program.