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.
Discovery curves for human viruses. (a) Virus discovery curve by species. A cumulative number of species reported to infect humans. Statistically significant upward breakpoints are shown (vertical lines). (b) Virus discovery curve by family. A cumulative number of families containing species reported to infect humans. (Copyright permission © 2012 The Royal Society).2
