Health officials confirmed Tuesday that a patient in Dallas has Ebola, marking the first such diagnosis of the deadly disease ever to occur on U.S. soil.

Until now, the only cases of Ebola in the U.S. have been Americans who were infected abroad and were brought back for treatment. The death toll from the worst Ebola outbreak ever, which has hit several countries in West Africa, surpassed 3,000 last week.

The patient, who has not been identified, had traveled to the U.S. from Liberia, leaving Liberia on Sept. 19 and arriving in the U.S. on Sept. 20. The patient had no symptoms when departing Liberia or when first landing in the U.S., but began developing symptoms for the deadly virus four days after arrival. On Sept. 28, the patient was placed in isolation at Texas Health Presbyterian Hospital in Dallas. The patient’s specimens tested positive for Ebola on Tuesday afternoon.

U.S. Centers for Disease Control and Prevention (CDC) director Dr. Tom Frieden said that the medical team’s priorities are to care for the patient, as well as to track down everyone the patient came in contact with while the patient was infectious. A patient with Ebola is only contagious once an infected person starts presenting symptoms. The CDC and Dallas Health and Human Services will identify all the contacts and monitor them for 21 days, which is the incubation period for the disease. If any of the contacts comes down with a fever, they will be isolated and cared for. The CDC says it has just started the contact tracing.

Frieden acknowledged that it’s possible someone with close contact with the patient could come down with the disease, but is confident the U.S. healthcare system can handle that possibility. “The bottom-line here is I have no doubt that we will control this case of Ebola so that it does not spread widely,” said Frieden during a news conference.

The CDC said that they do not know how the individual was infected, but the patient must have had close contact with someone infected with the disease. The CDC is sending disease specialists to Texas. The CDC has long acknowledged that it’s possible for Ebola to reach the U.S., though concern for widespread infections is low given the quality of U.S. health care. “As long as the outbreak continues in Africa, we need to be on-guard,” Frieden said.

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