Keywords
Legionnaire's disease
water cooling tower
evaporation condensers
How to Cite
Abstract
The measures of intervention adopted for the study and control of the outbreak are exposed. 126 systems with risk were found (45 of them high risk): 70 water cooling towers or similar, 35 decorative fountains, 1 building site with earth movement and 20 air-water closed systems, distributed by risk criteria.
Immediately were stopped: decorative fountains, washing down of streets, spray irrigation in parks and the building site.
486 inspections and 1040 sample taking were executed, the cleaning and disinfection of water cooling towers and similar systems were ordered and closing if necessary.
Afterwards, fills were replaced in water cooling tower which tested Lp positive.
After the investigation of 339 systems, 57 (16.9%) tested Lp positive culture, 23 (6.8 %) water cooling towers and 31 (9.1 %) drinking water taps.
Distribution by serotypes: LpS1 (62’3%), serotypes 2-14 (36’68%).
LpS1Olda Olda (21’74%) was the most abundant followed by LpS1 Pontiac Philadelphia Lugano (18’84%), in contrast to LpS1 Pontiac Philadelphia Glasgow (1’45%), found only in one case although isolated in the 18 samples of patients.
Culture and PCR were available in 355 cases, resulting in 30,8% sensitivity (confidence interval 95%, 25,1) and specificity 99,4±0,8.
There are a big percentage of samples positives to Lp Sg1 and between them prevail Lp Pontiac Philadelphia, basically Lugano kind.
The first disinfection doesn ́t eradicate all the contamination. The finding of 14 Lp positive systems after cleaning and disinfection process, with previous negative cultures, suggests a high analytical results variability and/or an inefficient first cleaning and disinfections of the system.
The previous conclusions and the low sensitivity of the PCR test must be considered in future cases.
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