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A patient being treated at a Dallas hospital is the first person diagnosed with Ebola in the United States, the Centers for Disease Control and Prevention announced Tuesday.

The man, whose identity was not released, left Liberia on September 19 and arrived in the United States on September 20, said Dr. Thomas Frieden, director of the CDC.

At that time, the individual did not have symptoms. “But four or five days later,” he began to exhibit them, Frieden said. The individual was hospitalized and isolated Sunday at Texas Health Presbyterian Hospital.

Citing privacy concerns, health officials declined to release any details about how the patient contracted the virus, what he was doing in Liberia or how he was being treated.

“I can say he is ill. He is under intensive care,” Edward Goodman of the hospital told reporters.

The patient is believed to have had a handful of contacts with people after showing symptoms of the virus, and before being hospitalized, Frieden said. A CDC team is en route to Texas to investigate those contacts.

At the same time, Frieden sought to play down the risk to public health. There currently are no other suspected cases of Ebola in Texas.

“It’s a severe disease, which has a high-case fatality rate, even with the best of care, but there are core, tried and true public health interventions that stop it,” Frieden said.

“The bottom line here is that I have no doubt that we will control this importation or this case of Ebola so that it does not spread widely in this country,” he said.

A number of other Americans have been diagnosed with the disease in West Africa and then brought to the United States for treatment.

The Ebola outbreak has been centered in the West African countries of Guinea, Sierra Leone and Liberia, though there have been concerns about international air travel and other factors — including the fact the symptoms might not appear until two to 21 days after one is infected — may contribute to its spread.

More than 3,000 people in West Africa have died after being infected with Ebola, according to a World Health Organization report (PDF) from last week. The same report stated that there had been 6,553 cases of the virus overall, though the number is suspected to be much higher, given difficulties in tracking and reporting the disease.

According to the CDC, Ebola causes viral hemorrhagic fever, which can affect multiple organ systems in the body and is often accompanied by bleeding.

Early symptoms include sudden onset of fever, weakness, muscle pain, headaches and a sore throat, each of which can be easily mistaken early on for other ailments like malaria, typhoid fever, meningitis or even the plague.