The first person has been diagnosed with Ebola in the city of Dallas, Texas and has been quarantined alongside 80 other possible contacts.
Thomas Eric Duncan, a former chauffeur made a trip from Liberia to the US on September 20.
Meanwhile, A cameraman working in Liberia has tested positive for Ebola and is to be flown home to the US for treatment.
The 33-year-old freelancer has been working in the country for three years for a number of media outlets, most recently NBC News.