(Adds quarantine of emergency responders)
By Julie Steenhuysen and Sharon Begley
Sept 30 (Reuters) - A man who flew from Liberia to Texas has become the first patient infected with the deadly Ebola virus to be diagnosed in the United States, health officials said on Tuesday, a sign the outbreak ravaging West Africa may spread globally.
The patient sought treatment six days after arriving in Texas on Sept. 20, Dr. Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention (CDC), told reporters. He was admitted two days later to an isolation room at Texas Health Presbyterian Hospital in Dallas.
U.S. health officials and lawmakers have been bracing for the eventuality that a patient would arrive on U.S. shores undetected, testing the preparedness of the nation's healthcare system. On Tuesday, Frieden and other health authorities said they were taking every step possible to ensure the virus did not spread widely.
"It is certainly possible someone who had contact with this individual could develop Ebola in the coming weeks," Frieden told a news conference. "I have no doubt we will stop this in its tracks in the United States."
Frieden said a handful of people, mostly family members, may have been exposed to the patient after he fell ill and that health authorities were tracking down anyone who might have had contact with the man. The emergency responders who transported the man to the hospital have been quarantined, according to a statement from Dallas city officials.
He said there was likely no threat to any airline passengers because the patient had no symptoms during his flight. Asked whether the patient was a U.S. citizen, Frieden described the person as a visitor to family in the country.
At least 3,091 people have died from Ebola in the worst outbreak on record that has been ravaging Liberia, Sierra Leone and Guinea in West Africa. More than 6,500 cases have been diagnosed, and the CDC has warned that the number of infections could rise to as many as 1.4 million people by early next year without a massive global intervention to contain the virus.
U.S. hospitals have treated, and released, three aid workers who were infected in Africa and flown back to the United States under strict medical supervision in a specially outfitted airplane.
A fourth person is being treated at Emory University Hospital in Atlanta, Georgia and a fifth person who may have been exposed to the virus is under observation at the National Institutes of Health in Bethesda, Maryland.
President Barack Obama discussed the Dallas case with Frieden on Tuesday, the White House said.
The Ebola outbreak has overwhelmed health systems in Africa, one of the world's poorest regions, prompting the U.S. government and other nations to send funds, supplies and personnel to stop its spread.
The Dallas case "underscores that Ebola is a global and national security issue and that we need to double-down on our efforts to help West Africa get this outbreak under control," Gerald Parker, vice president for Public Health Preparedness and Response at Texas A&M Health Science Center, said in an interview.
Frieden has said U.S. hospitals are well prepared to handle Ebola patients and has assured the public that the virus should not pose the same threat in the United States as it does in Africa.
"Americans need to remain calm and listen to the precautionary measures being suggested by the CDC," said Senator Chris Coons, a Democrat from Delaware who chairs the Senate Foreign Relations Subcommittee on African Affairs.
"It was only a matter of time before an Ebola case would emerge here in the United States, but as we're seeing in Dallas today, our public health system has the resources, capabilities, and knowledge to address and contain this virus quickly and safely."
Ebola symptoms generally appear between two and 21 days after infection, meaning there is a significant window during which an infected person can escape detection, allowing them to travel. Symptoms include fever, vomiting and diarrhea.
This outbreak has killed about 50 percent of its victims. In past outbreaks, fatality rates have been as high as 90 percent.
Frieden emphasized that Ebola cannot be spread through the air but only through contact with bodily fluids such as blood, diarrhea and tears.
He said that CDC and other health officials were discussing whether to treat the Ebola patient with an experimental drug.
Stocks in Tekmira Pharmaceuticals Corp and other small biotechnology companies working on Ebola therapies or vaccines rose on the news of the U.S. Ebola patient in after-hours trading. (Reporting by Julie Steenhuysen in Chicago and Sharon Begley in New York; Additional reporting by Steve Holland in Washington and Lisa Maria Garza in Dallas; Editing by Michele Gershberg and Lisa Shumaker)