Insurance companies negotiate with hospitals and doctors the price of every treatment, procedure and medical service. That price differs from hospital to hospital — even health plan to health plan. Vincent Wartner/Science Source hide caption

itoggle caption Vincent Wartner/Science Source

Ouch! Jeffrey Craig Hopper got good emergency treatment after being hit in the eye with a baseball in June. But months later he was slapped with an extra medical bill he never expected. Jennifer Hopper hide caption

itoggle caption Jennifer Hopper

A nurse at the University of California Medical Center in San Francisco protests lack of Ebola preparedness in October. The issue will be the focus of national demonstrations Wednesday. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images

Ebola patient Amber Vinson arrived by ambulance at Emory University Hospital on Oct. 15. Now healthy, Vinson was discharged from the hospital Tuesday. Kevin C. Cox/Getty Images hide caption

itoggle caption Kevin C. Cox/Getty Images

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

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

Dr. Wvennie MacDonald, the administrator of the JFK Memorial Hospital, has helped put new procedures in place to keep Ebola out, including a triage station to identify possible Ebola patients at the front gate. John W. Poole/NPR hide caption

itoggle caption John W. Poole/NPR

Ideally, the best place to care for someone ill with Ebola is at the end of a hall in a room with its own bathroom, anteroom and entrance, says Dr. Jack Ross of Hartford Hospital. Jeff Cohen/WNPR hide caption

itoggle caption Jeff Cohen/WNPR