Teams of workers have been sent in to clean the Texas apartment block where a US nurse lives, following her Ebola diagnosis.
She was involved in the treatment of the first person to be diagnosed with the virus in the US, before he died last week.
Officials have blamed a breach in protocol for her infection.
However, Melissa Repko from the Dallas Morning News says, although the woman has been interviewed by officials, it is still not known when or how she was exposed.
Ms Repko said: "She could not recall any specific breach, at this point the suspected breach is some kind of protocol, they are investigating to learn more.
"She was self-monitoring so she was taking her own temperature twice a day and she went to the hospital after detecting a fever on Friday and within 90 minutes was placed in isolation at the hospital after driving herself there."