1. Ronald L. Moolenaar, MD, is Associate Director for Science; Cynthia H. Cassell, PhD, is Lead for Applied Research; and Nancy W. Knight, MD, is Division Director; all in the Division of Global Health Protection, Center for Global Health, US Centers for Disease Control and Prevention, Atlanta, GA. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the US Centers for Disease Control and Prevention.