The worker of the hospital in Dallas reported a fever on Tuesday and was immediately placed in an isolation ward, the Texas Department of State Health Services said.
The person was among those who provided care for Liberia's Thomas Duncan who died from Ebola on October 8.
Texas health officials reported earlier that nurse Nina Pham who had contact with Duncan had tested positive for the virus that has already killed more than 4,400 people in West Africa.
The death toll of the Ebola outbreak reached 4,447 on Tuesday. and the umber of probable and suspected cases stands at more than 8,900.
The World Health Organization describes Ebola virus disease (formerly known as Ebola haemorrhagic fever) as a severe, often fatal illness, with a case fatality rate of up to 90%.
Symptoms include sudden onset of fever, intense weakness, muscle pain, headache and sore throat. This is followed by vomiting, diarrhoea, rash, impaired kidney and liver function, and in some cases, both internal and external bleeding. T
he infection is transmitted by direct contact with the blood, body fluids and tissues of infected animals or people. People are infectious as long as their blood and secretions contain the virus. The incubation period is 2 to 21 days.
There is no known cure or vaccine for the disease. The only treatment offered is “supportive intensive care.” During an outbreak, those at higher risk of infection are health workers, family members and others in close contact with sick people and deceased patients.