NBC reported that Ashka Mukpo, who has worked in Liberia for three years and covered the current Ebola outbreak for various outlets, began experiencing symptoms Wednesday and tested positive for the virus late on Thursday.

Four other NBC News team members who had shown no signs of infection would return to the United States to undergo a precautionary quarantine, the network announced late Thursday.

"The good news is this young man, our colleague, was admitted very, very early," medical correspondent Dr. Nancy Snyderman, a physician, told MSNBC host Rachel Maddow. "He's in good spirits."

Snyderman said journalists carried thermometers and avoid handshakes and hugs, washed their hands with diluted bleach and water, and dipped their feet into bleach solution before entering hotels or other public places. She believes Mukpo contracted Ebola before he began working for NBC Tuesday.

She offered no particulars as to how he might have contracted the virus, transmitted through contact with the bodily fluids of those infected.

The doctor added that she and the other members of the NBC News team felt well and had not shown symptoms of Ebola, but would follow - and exceed - guidelines set by the US Centers for Disease Control and Prevention for their safety and that of others.

'Clear international dimension'

NBC News President Deborah Turness wrote that as a precaution the network would charter a plane to fly Snyderman and the rest of the crew back to the United States, where they would place themselves under quarantine for 21 days: "at the most conservative end of the spectrum of medical guidance." The first symptoms tend to appear within eight to 10 days.

US health officials continue to monitor more than 80 people in Texas who had potential contact with a Liberian man diagnosed with Ebola and have ordered four of his family members to stay home.

Officials had previously confirmed infections in four other Americans, all doctors or relief workers sent back to the United States for medical treatment. The current outbreak has killed at least 3,300 people so far, almost all of them in Guinea, Liberia and Sierra Leone.

Liberia expressed official "regret" over the spread of the virus to the Unitzed States, releasing a statement that the incidents had demonstrated "the clear international dimension of this Ebola crisis."

mkg/ipj (Reuters, AFP, dpa, AP)