Tuberculosis outbreaks predicted by characteristics of first patients in a DNA fingerprint cluster.
BACKGROUND
Some clusters of patients who have Mycobacterium tuberculosis isolates with identical DNA fingerprint patterns grow faster than others. It is unclear what predictors determine cluster growth.


OBJECTIVE
To assess whether the development of a tuberculosis (TB) outbreak can be predicted by the characteristics of its first two patients.


METHODS
Demographic and clinical data of all culture-confirmed patients with TB in the Netherlands from 1993 through 2004 were combined with DNA fingerprint data. Clusters were restricted to cluster episodes of 2 years to only detect newly arising clusters. Characteristics of the first two patients were compared between small (2-4 cases) and large (5 or more cases) cluster episodes.


RESULTS
Of 5,454 clustered cases, 1,756 (32%) were part of a cluster episode of 2 years. Of 622 cluster episodes, 54 (9%) were large and 568 (91%) were small episodes. Independent predictors for large cluster episodes were as follows: less than 3 months' time between the diagnosis of the first two patients, one or both patients were young (<35 yr), both patients lived in an urban area, and both patients came from sub-Saharan Africa.


CONCLUSIONS
In the Netherlands, patients in new cluster episodes should be screened for these risk factors. When the risk pattern applies, targeted interventions (e.g., intensified contact investigation) should be considered to prevent further cluster expansion.
Kik
Sandra V
SV
KNCV Tuberculosis Foundation, PO Box 146, 2501 CC The Hague, The Netherlands. kiks@kncvtbc.nl
Verver
Suzanne
S
van Soolingen
Dick
D
de Haas
Petra E W
PE
Cobelens
Frank G
FG
Kremer
Kristin
K
van Deutekom
Henk
H
Borgdorff
Martien W
MW
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000032:analysis*; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D017720:Molecular Epidemiology; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000302:isolation & purification; D009426:Netherlands / Q000453:epidemiology; D014376:Tuberculosis / Q000453:epidemiology* / Q000382:microbiology
D004269:DNA, Bacterial