Police officers stand outside the home of Craig Spencer, a Doctors Without Borders physician who recently returned to the city after treating Ebola patients in West Africa, on Thursday in New York. Spencer tested positive for the virus, according to preliminary test results, city officials said. John Minchillo/AP hide caption

itoggle caption John Minchillo/AP

Data sources: David Ropeik/Harvard University, National Weather Service, World Health Organization, Northeastern University Laboratory for the Modeling of Biological and Socio-Technical Systems, National Geographic, United States Census Adam Cole and Ryan Kellman/NPR hide caption

itoggle caption Adam Cole and Ryan Kellman/NPR

The headquarters of Reynolds American in downtown Winston-Salem, N.C.. Starting in January, workers there will no longer be allowed to smoke at their desks. Chris Keane/Reuters/Landov hide caption

itoggle caption Chris Keane/Reuters/Landov

The problem isn't just that fake cures are worthless, doctors say. Fraudulent claims also give some people the false sense that the product can protect them from getting sick. iStockphoto hide caption

itoggle caption iStockphoto

At the onset of symptoms, Dr. Adaora Ingonoh (center) and her colleagues began drinking oral rehydration solution. It doesn't taste great but they say it helped them survive Ebola. They each downed over a gallon a day for nearly a week. Andrew Esiebo/Courtesy of WHO hide caption

itoggle caption Andrew Esiebo/Courtesy of WHO

A rogues gallery of the viruses (left to right) that cause MERS, SARS, and influenza. Niaid; 3D4Medical; Niaid/Science Source hide caption

itoggle caption Niaid; 3D4Medical; Niaid/Science Source

Amber Vinson in a photograph taken earlier this week at Emory University Hospital in Atlanta. Officials at Emory and the Centers for Disease Control and Prevention couldn't detect Ebola in Amber Vinson as of Tuesday evening, her family said in a statement. AP hide caption

itoggle caption AP

Bellevue Hospital nurse Belkys Fortune (left) and Teressa Celia, associate director of infection prevention and control, during a demonstration of procedures for possible Ebola patients on Oct. 8. Richard Drew/AP hide caption

itoggle caption Richard Drew/AP