Outbreak detection and secondary prevention of Legionnaires' disease: a national approach.
BACKGROUND
To stop a possible outbreak of Legionnaires' disease (LD) at an early stage an outbreak detection programme was installed in The Netherlands.


METHODS
The programme consisted of sampling and controlling of potential sources to which LD patients had been exposed during their incubation period. Potential sources were considered to be true sources of infection if two or more LD patients (cluster) had visited them, or if available patients' isolates and environmental Legionella spp. were indistinguishable by amplified fragment length polymorphism genotyping.


RESULTS
Rapid sampling and genotyping as well as cluster recognition helped to target control measures. Despite these measures, two small outbreaks were only stopped after renewal of the water system. The combination of genotyping and cluster recognition lead to 29 of 190 (15%) patient-source associations.


CONCLUSIONS
Systematic sampling and cluster recognition can contribute to outbreak detection and lead to cost-effective secondary prevention of Legionnaires' disease.
Den Boer
Jeroen W
JW
Municipal Health Service Kennemerland, P.O. Box 5514, 2000 GM Haarlem, The Netherlands. jwdenboer@hdk.nl
Verhoef
Linda
L
Bencini
Max A
MA
Bruin
Jacob P
JP
Jansen
R
R
Yzerman
Ed P F
EP
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D016952:Legionella pneumophila / Q000302:isolation & purification; D007877:Legionnaires' Disease / Q000453:epidemiology* / Q000517:prevention & control* / Q000635:transmission; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D014871:Water Microbiology; D014881:Water Supply