Media playback is unsupported on your device Media caption The man went to a Dallas emergency room on Friday, but was sent home with antibiotics, as Alastair Leithead reports

Five children in Texas who came into contact with a man infected with Ebola are being monitored at home.

At a news conference at Texas Health Presbyterian Hospital in Dallas, the state's governor Rick Perry said parents were concerned but he allayed fears of contagion.

Officials said they are monitoring up to another dozen people who may have come into contact with the man.

Thomas Eric Duncan is thought to have contracted the virus in Liberia.

The Liberian national came to the US nearly two weeks ago to visit relatives and he is the first man to be diagnosed with Ebola while in the US.

Mr Duncan is now in a serious condition, a spokeswoman for the hospital said.

A nurse had asked him on his first visit to the hospital when he felt ill if he had been in an area affected by the Ebola outbreak.

He told them he had been to Liberia but the "information was not fully communicated throughout the whole team", according to hospital officials.

Mr Duncan was then sent home with antibiotics - a decision hospital bosses have described as a matter of "regret" - but he was admitted when he returned two days later.

Media playback is unsupported on your device Media caption Texas Governor Rick Perry: "I know that parents are extremely concerned"

Allaying fears that Mr Duncan might have infected others, Mr Perry said his state had the medical infrastructure to prevent an outbreak.

"There are few places in the world better equipped to meet the challenge that is posed in this case."

More than 3,000 people have already died of Ebola in West Africa and a small number of US aid workers have recovered after being flown to the US.

Meanwhile, in Liberia a government spokesman said the man showed no symptoms or fever as he was screened before departing the country.

"What this incident demonstrates is the clear international dimension of this Ebola crisis," Lewis Brown, the country's information minister, said in a statement.

Image copyright AFP Image caption Liberia has been worst affected by the Ebola outbreak which began in neighbouring Guinea

"For months, the Liberian government has been stressing that this disease is not simply a Liberian or West African problem."

Binyah Kesselly, chairman of the board of the Liberia Airport Authority, said they had screened 10,000 passengers since July, but it would be "nearly impossible" to identify a person as infected with the Ebola virus if they were not showing symptoms.

CDC Director Thomas Frieden confirmed the Ebola case on Tuesday, saying the unnamed patient left Liberia on 19 September and arrived in the US the next day to visit relatives, without displaying any symptoms of the virus.

Image copyright EPA Image caption Texas Health Presbyterian Hospital says it was prepared for a potential case

Symptoms became apparent in the patient on 24 September, and on 28 September he was admitted to a Texas hospital and put in isolation.

The disease, which is not contagious until symptoms appear, is spread via close contact with bodily fluids.

Health officials are working to identify all people who came into contact with Mr Duncan and they will then be monitored for 21 days to see if an Ebola-related fever develops.

Image copyright EPA Image caption More than 3,000 people have died in West Africa from Ebola, many in Liberia

But they will not be monitoring passengers on the man's flight, where Dr Frieden said there was "zero risk of transmission" as the man had been checked for fever before boarding.

According to Dr Frieden, it is possible a family member who came in direct contact with the patient may develop Ebola in the coming weeks.

But "the bottom line here is I have no doubt that we will control this importation, this case of Ebola, so it does not spread widely in this country," he added. "We will stop it here."

A handful of American aid workers have recovered after flying back to the US for treatment.

Ebola virus disease (EVD)

Image copyright SPL

Symptoms include high fever, bleeding and central nervous system damage

Spread by body fluids, such as blood and saliva

Fatality rate can reach 90% - but current outbreak has mortality rate of about 70%

Incubation period is two to 21 days

There is no proven vaccine or cure

Supportive care such as rehydrating patients who have diarrhoea and vomiting can help recovery

Fruit bats, a delicacy for some West Africans, are considered to be virus's natural host

Ebola virus: Busting the myths