1. Centers for Disease Control and Prevention, Atlanta, Georgia, USA; †Bishop, California, USA; ‡California Department of Health Services, Sacramento, California, USA; §California Department of Health Services, Berkeley, California, USA; ¶Bureau of Disease Control and Intervention Services, Carson City, Nevada, USA; #Nevada State Health Division, Carson City, Nevada, USA; **Colorado Department of Public Health & Environment, Denver, Colorado, USA; and ††Utah Department of Health, Salt Lake City, Utah, USA