1. Centers for Disease Control and Prevention , Division of Vector-Borne Diseases, Fort Collins, Colorado , USA
2. Missouri Department of Health and Senior Services , Jefferson City, Missouri , USA
3. Public Health—Seattle and King County , Seattle, Washington , USA
4. Washington State Department of Health , Shoreline, Washington , USA
5. Colorado Department of Public Health and Environment , Denver, Colorado , USA
6. EvergreenHealth , Kirkland, Washington , USA