The bigger risk of Ebola

(CNN) – Ebola going airborne would be devastating, says Dr. Michael Osterholm, with the Center for Infectious Disease Research and Policy. But he said such a mutation of the disease is not a big risk.

"A much bigger risk is this virus moving out of West Africa and getting into the slum areas like Lagos and Nairobi and making the cases in West Africa only a small part of the outbreak," Osterholm said in an interview with CNN's "The Lead with Jake Tapper."

As of October 3, there have been 7,491 reported cases of Ebola in West Africa, according to the World Health Organization.

When this Ebola outbreak spreads beyond West Africa, says Osterholm, "the rest of the world will continue to feel those sparks flying out of Africa and landing throughout the world."

Spain reported the first known person to contract Ebola outside of Africa in the current outbreak Monday. A nurse contracted the disease after treating a missionary worker and a priest, both of whom were infected while working in West Africa.

Given the cumbersome protective gear and the difficult circumstances doctors, nurses, and health care workers face caring for Ebola patients, Osterholm said he is surprised that so few of them have become infected.

"You're putting those outfits on and off. To me, it's almost like running across the freeway six or seven times a day and hoping you don't get hit doing that, because outside those particular garments may be contaminated," he said.

For more of our interview with Dr. Michael Osterholm, check out the video above.