A Texas health care worker who was part of the team treating the first US Ebola case has contracted the disease.

The health care worker at the Texas Health Presbyterian Hospital reported a low-grade fever Friday night and was isolated and referred for testing, the Texas Department of State Health Services said in a statement.

"We knew a second case could be a reality, and we've been preparing for this possibility," said Dr. David Lakey, commissioner of the health service.

The first person in the United States diagnosed with Ebola, Liberia citizen Thomas Eric Duncan, died in an isolation ward of the Dallas hospital on Oct. 8, 11 days after being admitted.

The U.S. government has since ordered five airports to start screening passengers from West Africa for fever.

The number of people known to have died in the worst Ebola outbreak on record has risen to 4,033 out of 8,399 cases in seven countries, the World Health Organization said on Friday.

The test result is preliminary.

Health care workers are at the highest risk for contracting the disease. But it's amazing that with all the precautions they took, she still caught the virus. Thankfully, they were able to diagnose the virus in the very early stages and her chances of a recovery are good.