Barack Obama has conceded it "may be appropriate" to choose an Ebola "tsar" to lead the US response against the disease.

President Barack Obama vowed his administration would respond in a “much more aggressive way” to cases of Ebola in the United States.

Fears of the ebola virus have deepened with word that a second US nurse caught the disease from a patient and flew across the country’s mid-west aboard an airliner the day before she was diagnosed.