Officials warned Saturday that the risk of more Ebola cases in the U.S. won't be considered eradicated for weeks. Reuters

Thomas Eric Duncan, the Dallas patient with the first confirmed case of Ebola virus disease in the U.S., is in critical condition, a representative of Texas Health Presbyterian Hospital said Saturday. The U.S. Centers for Disease Control and Prevention said earlier that Duncan was in intensive care, CNN reported.

Meanwhile, as public-health officials rush to prevent an outbreak of the deadly virus in Texas’ third-largest city, the CDC warned it will take more than a month before the threat of more cases can be considered eradicated.

The CDC’s director, Dr. Tom Frieden, said in a media briefing that the threat will end 42 days after Duncan was placed into isolation on Sept. 28. As the Los Angeles Times reported, the incubation period for Ebola is 21 days, and officials typically wait twice that length of time before saying the risk of more cases has subsided. If new cases are confirmed, then the countdown clock will start over again.

The CDC said a total of 114 people who came into contact with Duncan have been tested, but none are exhibiting symptoms. About 10 of those people are considered to be higher risk, including, likely, Duncan’s partner, her 13-year-old son and two nephews, CNN said.

Duncan is a resident of Liberia, where the disease has killed 2,069 people, CDC reported, while outbreaks in other West African nations have killed more than 1,300. The patient had made a trip to the same hospital Sept. 20, but was released without being correctly diagnosed.

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