An American TV cameraman has tested positive for the Ebola virus in Liberia. The 33-year-old freelancer working for NBC News is being flown home to the US for treatment, the network said in its own online report.

One hundred people are being checked for exposure to Ebola in Texas after a Liberian national was diagnosed with the virus in Dallas on Tuesday.

Thomas Eric Duncan remains in a serious condition.

Four of his relatives have been ordered to remain at home, while parents took their children out of school in the city as health authorities track potential contagion

“The only person who had symptoms is Mr. Duncan who is in the hospital,” explained Dallas County Judge, Clay Jenkins at a press conference. “Nobody who has been around Mr. Duncan during the time that he has been symptomatic has shown any indication of having contracted Ebola.”

The White House said US President Barack Obama was in contact with Mayor Mike Rawlings concerning the local, state and federal response to the Ebola case.

David Daigle, from the Center for Disease Control and Prevention aimed to play down fears of any mass contagion saying: “I think you’ve already heard there’s a list of about 100 what we call potential or possible contacts. That will be culled down into a list that we can begin the contact tracing on”.

Liberian officials said they would prosecute Mr Duncan for lying about being in contact with people suffering from Ebola before boarding a flight to the US.

Authorities in West Africa are struggling to contain the virus which is spreading at an alarming rate with new cases doubling every few weeks.