The greatest challenge to isolating and treating everyone with Ebola by the end of the year? Tracking them down, says Bruce Aylward, an emergencies expert at the World Health Organization. That’s where medical detective work comes in.

Health workers seek out Ebola cases and evaluate the threat each poses to the general public through contact tracing.

  • They interview the infected patient and identify his or her exposure to the virus as high, low or intermediate. Then they create a list of everyone with whom the patient has come into contact.

  • They monitor these contacts for signs of illness for 21 days (Ebola’s incubation period) from the last exposure to the Ebola patient.

  • If a contact develops symptoms, health workers immediately isolate, test and administer appropriate medical care.

  • Then the cycle starts again: All of the new patient’s contacts are identified and monitored for 21 days.

By quickly finding and isolating new Ebola cases, contact tracing stops further spread of the virus. The Centers for Disease Control and Prevention warns that “even one missed contact can keep the outbreak going.”

The U.S. trains international reporters on how to cover Ebola and hosts Ebola preparedness workshops in high-risk countries. Workshops include training in proper contact tracing.