Full text
PDFPage 581
. 1990 Feb;56(2):581. doi: 10.1128/aem.56.2.581-581.1990
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.