With confirmed Ebola-infected patients in the United States and in Spain, experts are now worried about the possibility of the virus spreading more easily than initially thought, reported the LA Times.

But, experts of the Centers for Disease Control and Prevention maintain that there are still parameters of the disease that can be monitored to prevent the spread of history's worst outbreak of Ebola.

Citing that a fever of at least 101.5 degrees is necessary for an air traveler to transmit the virus, the LA Times quoted CDC director Dr. Thomas Frieden who assured the public that "there is zero risk of transmission on the flight."

Additionally, Dr. Edward Goodman of Texas Health Presbyterian Hospital in Dallas, where the US-based patient is being treated and is in critical condition, said that "Ebola is not transmitted by the air. It is not an airborne infection."

However, Dr. C.J. Peters says that "he would not rule out the possibility that it spreads through the air in tight quarters...," quoted the LA Times. Peters is a prominent expert of the Ebola virus, having been part of the 1989 outbreak of the virus in research monkeys.

He is of the position that we still aren't in the position to make definitive assurances.

"We just don't have the data to exclude it," said Peters, who led a study with the CDC on Ebola's transmissibility in humans and is presently doing research on viral diseases at the University of Texas in Galveston.

Supporting such sentiments, virologist Dr. Philip K. Russell, who is also researching about the virus, says there is much more to learn. "Being dogmatic is, I think, ill-advised, because there are too many unknowns here." 

With no known medical cure, the virus has infected nearly 7,500 people and caused more than 3,400 deaths. The rapidly-spreading outbreak in West Africa may still evolve into a mutation which, as of now, we don't know much about, said Russell.

The increase in public clamor for answers and better response comes following a Spanish nurse's contraction of the deadly disease. The unnamed nurse becomes the first Ebola victim to contract the disease outside of Africa.

Mail Online reported that the woman was believed to have been part of the team which treated infected patient Manuel Garcia who died on Sept. 26 following missionary work in Africa.

Garcia was brought back from Africa to seek treatment for the virus, which he contracted in Sierra Leone.