Six crucial factors for Ebola hunting "contact tracers"

A team of medical professionals are racing to locate at least 60 people who came in contact with a man named Patrick Sawyer, who died from the Ebola virus shortly after flying between Liberia and Nigeria last week. Health officials are using a method called "contact tracing" to find all the identify and monitor those who may have come in contact with Sawyer. Infectious disease specialistDr. David Heymann explains the process and its challenges.

Dr. David Heymann is a professor of infectious diseases at the London School of Hygiene and Tropical Medicine who has worked on many different outbreaks of Ebola and headed the World Health Organization's response to the 2003 SARS outbreak. Heymann said there are several key factors to ensure complete and successful contact tracing.

1) Find the index case

The index case is the first person with the virus to be identified, Heymann said. Nigerian officials knew right away that Patrick Sawyer was the index case of Ebola in the country.

2) Expand the circle

From the index case, health officials attempt to find everyone who may have had contact with that person, Heymann said.

The immediate circle surrounding Patrick Sawyer is anyone who was on the same flight as him travelling from Monrovia to Lagos, and anyone else he may have had contact with during his travels.

3) Paint the big picture

Once contacts are identified, it's important for them to understand their role in stopping the spread, Heymann said.

"It's important that they understand what it means to be a contact and what their responsibility is, not only to themselves, but to their family members and community," he said.

4) Don't lose track of them

According to Heymann Health officials keep track of contacts for the full incubation period. Ebola can take up to three weeks to show symptoms in an infected person. This means that health care workers are looking for any signs of fever, headache, vomiting and diarrhea.

5) Gain trust, work together

In West Africa, some locals have been reluctant to interact with doctors because of rumours that foreign health workers are spreading the Ebola virus.

"Contact tracing cannot be done unless there's full collaboration of the national government, the local government and respected people and other groups in the community," Heymann said.

6) Know that diseases don't carry passports

"What we learned from the SARS outbreak and what we're learning from this outbreak is that international borders can not stop the spread of infectious disease," Heymann said.

Strong public health is key to preventing the spread of an infectious disease across borders, he said. Disease detection and rapid response systems are essential for identifying and stopping a possible outbreak before it starts.