Temporal Trends in Bordetella pertussis Populations, Denmark, 1949–2010
Randi Føns Petersen , Tine Dalby, Ditte Marie Dragsted, Frits Mooi, and Lotte Lambertsen
Author affiliations: Statens Serum Institut, Copenhagen, Denmark (R.F. Petersen, T. Dalby, L. Lambertsen); private practitioner, Frederiksberg, Denmark (D.M. Dragsted); National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands (F. Mooi)
Figure 1. . . Multilocus variable-number tandem repeat analysis types (MT) of 260 Bordetella pertussis isolates collected in Denmark during 1949–2010. A minimum spanning tree based on the categorical clustering of MTs. Each MT is represented by a circle, and the Dutch type name (15) is indicated. MTs connected by heavy short lines, thinner lines, dashed lines, and spotted lines designate 1, 2, 3, and 4 loci differences, respectively. *New MTs detected in this study. Circle size indicates the number of isolates with the particular MT. Colors indicate the time period of isolation: green, period 1 (1961 and earlier); red, period 2 (1962–1996); purple, period 3 (1997 forward).
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