FIG. 1.
Increase in frequency of PNSP in Poland from 1998 to 2002 (solid lines) and proportion of isolates belonging to the Spain9V-3 clone, ST413, and its SLVs among all the isolates in corresponding years (dashed lines).
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.