This undated electron microscopic (EM) handout image provided by the Centers for Disease Control and Prevention depicts a monkeypox virion, obtained from a clinical sample associated with the 2003 prairie dog outbreak. - It was a thin section image from a human skin sample. On the left were mature, oval-shaped virus particles, and on the right were the crescents, and spherical particles of immature virions. (Photo by Cynthia S. Goldsmith / Centers for Disease Control and Prevention / AFP) / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / Cynthia S. Goldsmith, Russell Regnery / Centers for Disease Control and Prevention " - NO MARKETING - NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS