Dr. Komba Songu M'Briwah, left, talks on the phone while staff members disinfect offices at the Hastings Ebola Treatment Center in Freetown. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

India has record no Ebola cases, but the country is on high alert and has quarantined hundreds of travelers from West Africa. This hospital in New Delhi has set up an Intensive Care Unit for potential Ebola patients. Sajjad Hussain/AFP/Getty Images hide caption

itoggle caption Sajjad Hussain/AFP/Getty Images

A woman on the L train in New York City last week covers her face, fearful because a doctor with Ebola rode the train days earlier. Epidemiologists say people on the subway were not at risk. Stephen Nessen /WNYC hide caption

itoggle caption Stephen Nessen /WNYC

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

The cruise ship Carnival Magic floats behind a catamaran off Cozumel, Mexico on Oct. 17. The ship skipped a planned stop there Friday, the cruise line says, after Mexican authorities delayed granting permission to dock. Reuters/Landov hide caption

itoggle caption Reuters/Landov

The Rev. Herman Browne voluntarily quarantined himself for 21 days after his wife's friend tested positive for Ebola. On Sunday, he returned to his church, Trinity Cathedral, to preach to his congregation about Ebola prevention. Jon Hamilton/NPR hide caption

itoggle caption Jon Hamilton/NPR

Avian influenza, or bird flu, causes an infectious and contagious respiratory disease. In the lab, several scientists have made the H5N1 strain more contagious, a controversial line of research. James Cavallini/ScienceSource hide caption

itoggle caption James Cavallini/ScienceSource

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

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