Impeding air travel to West Africa might stop the spread of Ebola to the United States temporarily, but would be harmful to stopping its spread in the region and eventually to America's borders, a CDC official said in a hearing Friday afternoon.

"We are already at the point where we believe all stops need to be pulled out in preventing the growth of the disease in Africa, and that's what we need to focus on, because the risk in this country will not be eliminated until we eliminate the spread of the disease in Africa," said Toby Merlin, director of the Centers for Disease Control and Prevention (CDC) division of preparedness and emerging infection. Merlin spoke at the hearing, which was hosted by the U.S. House of Representatives Homeland Security Committee at the Dallas Fort Worth International Airport.

The hearing was held just days after the death of Thomas E. Duncan, the first person diagnosed with Ebola in the United States. Duncan had traveled from Liberia to the United States by flights through Brussels and Washington Dulles International Airport before landing in Dallas where he went to stay with his family. He then developed symptoms of Ebola, was taken to the hospital, initially told to return home, and then returned to the hospital where he remained in isolation until his death. His diagnosis launched a rapid response from federal, state, and local agencies in their effort to isolate Duncan, his family, and begin locating anyone he may have come into contact with while contagious.

Rep. Michael McCaul (R-TX), chairman of the committee, called Congress members out of recess for the hearing to discuss this response, along with the international efforts in Africa and U.S. preparedness for an Ebola outbreak. A major portion of questioning of witnesses focused on the impact of travel bans from and to West Africa to stop people from spreading the disease to the United States.

Merlin said that he understood why some individuals might be in favor of a travel ban, but it would impede progress in stopping the epidemic from spreading. "We have a disease now that we understand the range of how many people are infected and we know how many people will be infected next month if nothing is done," Merlin explained. "We know the size and the scale of the international effort that is required to stop it. We have good projections on how many deaths will be caused by delay. And we are very afraid that things that are done to impede travel will delay that intervention."

If interventions are delayed in Africa, Merlin said the CDC is concerned that the epidemic will spread out of Sierra Leone, Guinea, and Liberia, to other countries and become endemic in Africa, potentially spreading to other parts of the world. This is because although the U.S. military is playing a role in the international intervention effort, there are many individuals traveling to the region from the U.S., Europe, China, and Cuba, who are taking commercial flights and would be hindered in their efforts if a travel ban was put in place.

We will not be safe until we stop the growth of Ebola because it is now infected so many people and it is reproducing so quickly that it will inevitably become endemic and it will inevitably be a greater threat, he explained.

Instead of stopping air travel in and out of the affected region, Rep. Ron Barber (D-AZ) asked if there were additional screening measures that could be put in place prior to when travelers get to the airport. "Would it be helpful to require individuals who are not U.S. citizens or residents to go through the local American consulate to get a visa and implement screening at that location before they embark?" he said.

John Wagner, assistant commissioner for the U.S. Customs and Border Protection (CBP) office of field operations, said that travelers to the United States from West Africa are already required to have a visa, and that when they apply, if they have any communicable diseases they will not be granted a visa. However, if they develop a disease after receiving their visa the consulate cannot revoke the visa and any additional screening measures would need to be implemented by the U.S. State Department.

Wagner also said that CBP was prepared to implement enhanced screening measures that were announced earlier in the week and will go into effect this weekend at five U.S. airports, which receive more than 94 percent of travelers from Guinea, Liberia, and Sierra Leone: Hartsfield-Jackson Atlanta International Airport, JFK International Airport, O'Hare International Airport, Dulles International Airport, and Newark Liberty International Airport.

The measures include escorting travelers from the three countries to an area of the airport set aside for screening, observation by CBP staff for signs of illness and temperature readings, and if they show signs of symptoms of Ebola, additional evaluations by a CDC quarantine station public health officer. Travelers who do not show signs of the disease will also receive health information for self-monitoring.