Volume 18, Number 5—May 2012
Research
Temporal Trends in Bordetella pertussis Populations, Denmark, 1949–2010
Figure 3

Figure 3. . . Temporal trends in the frequencies of the alleles of pertactin (prn) (A), the pertussis toxin subunit S1 (ptxA) (B), the pertussis toxin promoter (ptxP) (C), and the tracheal colonization factor A (tcfA) (D) of Bordetella pertussis isolates collected in Denmark, 1949–2010. The number of isolates analyzed each year/years is given above each column. Years containing 1 or 2 isolates are combined with another year in the same time period, as indicated