An official at the University of Michigan Health System in Ann Arbor says its mix of patients helps explain the infection rates. Scott C. Soderberg/Courtesy of University of Michigan Health System hide caption

itoggle caption Scott C. Soderberg/Courtesy of University of Michigan Health System

Thomas Eric Duncan, the first Ebola patient diagnosed in the U.S., at a wedding in Ghana. Texas Health Presbyterian Hospital Dallas, where Duncan was being treated for the disease, on Wednesday, Oct. 8, 2014 said Duncan has died. Wilmot Chayee/AP hide caption

itoggle caption Wilmot Chayee/AP

Members of the California Nurses Association rallied in Sacramento, Calif., in May, in anticipation of contract negotiations with Kaiser Permanente that began in this fall. April Dembosky / KQED hide caption

itoggle caption April Dembosky / KQED

One rationale for extending Medicaid coverage to more people is to help them get to a doctor or clinic before a minor illness becomes a medical emergency. iStockphoto hide caption

itoggle caption iStockphoto

An ambulance carrying Amber Vinson, the second health care worker to be diagnosed with Ebola in Texas, arrives at Emory University Hospital in Atlanta on Wednesday. David Tulis/AP hide caption

itoggle caption David Tulis/AP

A man walks past the former site of a clinic that offered abortions in El Paso, Texas. Juan Carlos Llorca/AP hide caption

itoggle caption Juan Carlos Llorca/AP

Scenes from an outbreak: Ebola survivor Dr. Kent Brantly; Texas Health Presbyterian Hospital in Dallas; A worker cleans the apartment where Ebola victim Thomas Eric Duncan stayed in Dallas; experimental vaccine; the Carnival Magic cruise ship off Cozumel, Mexico. Jessica McGowan/Getty; Mike Stone/Getty Images; Jim Young/Reuters/Landov; Steve Parsons/AP; Angel Castellanos/AP hide caption

itoggle caption Jessica McGowan/Getty; Mike Stone/Getty Images; Jim Young/Reuters/Landov; Steve Parsons/AP; Angel Castellanos/AP

Alana and Troy Pack died in 2003 when a woman abusing pain pills hit the children with her car. The accident has led to a ballot measure that, among other things, would put new constraints on physicians. Courtesy of the Pack family hide caption

itoggle caption Courtesy of the Pack family

Nina Pham, shown here in a 2010 college yearbook photo, became infected with Ebola virus while caring for Thomas Eric Duncan in a Dallas hospital. Courtesy of tcu360.com/AP hide caption

itoggle caption Courtesy of tcu360.com/AP