Looking for His glorious appearing! Titus 2:13

The number of people infected with the Ebola virus has passed 10,000, with 4992 deaths, according to the World Health Organisation, as the United States announced its ambassador to the United Nations would visit the three worst-affected West African nations.

It says 10,141 people have been diagnosed with the deadly disease, which is an increase from the previous estimate of about nine thousand cases.

Almost five thousand people have died from the virus, which has hit Guinea, Liberia and Sierra Leone the hardest. Washington's ambassador to the UN, Samantha Power, was set to land in the capital of Guinea, Conakry, last night.

A chid stands near a sign advising of a quarantined home in Sierra Leone. Photo: AP

Mali became the latest nation to record a death when a two-year-old girl died there on Saturday. More than 40 people known to have come into contact with her have been placed in quarantine.

The toddler had taken a 1000-kilometre bus journey from neighbouring Guinea before being treated.

Malian President Ibrahim Boubacar Keita told French radio:  "We are doing everything to prevent panic and psychosis.

Gearing up: A nurse demonstrates protective equipment during an Ebola educational session for healthcare workers in New York. Photo: Reuters

"Since the start of this epidemic, we in Mali took all measures to be safe, but we can never hermetically seal ourselves from this," he said. "Guinea is a neighbouring country, we have a common border that we have not closed and that we will not close."

Mauritania, which neighbours Mali,  reinforced controls on its border, according to local sources.

The WHO said it was treating the situation in Mali as an "emergency" because the toddler had travelled for hundreds of kilometres on public transport with her grandmother while showing symptoms of the disease - meaning that she was contagious.

The girl and her grandmother travelled by public transport from Keweni in Guinea through the towns of Kankan, Sigouri and Kouremale to the Malian capital, Bamako.

Mali's health ministry however denied that the girl had been showing symptoms before she reached the town of Kayes.

A tonne of medical supplies was dispatched from WHO stocks in Liberia to Bamako late on Friday.

New York City's first Ebola case, 33-year-old doctor Craig Spencer who fell ill one week after returning from treating patients in Guinea, was said to be in a stable condition in isolation at the city's Bellevue Hospital Center.

His fiancee and two of his friends are in quarantine but appear healthy, officials said.

In the wake of his diagnosis in the country's largest city, the US states of New York and New Jersey ordered mandatory quarantines of 21 days - the maximum gestation period for Ebola - for any individuals who have had direct contact with an Ebola patient while in the worst affected countries.

One nurse who was being quarantined at a New Jersey hospital after working with Ebola patients in Sierra Leone criticised her treatment as an overreaction after an initial test found that she did not have the virus.

"I am scared about how health care workers will be treated at airports when they declare that they have been fighting Ebola in West Africa," the nurse, Kaci Hickox, wrote in an essay on the website of The Dallas Morning News. "I am scared that, like me, they will arrive and see a frenzy of disorganisation, fear, and most frightening, quarantine."

She described having been held in isolation for about seven hours at Newark Liberty International Airport on Friday, left alone for long stretches and given only a granola bar when she had said she was hungry.

Ms Hickox disputed that she had had a fever. She wrote that at the airport, a forehead scanner showed her temperature to be 38 degrees, but that came after four hours during which she had not been allowed to leave.

"My cheeks were flushed, I was upset at being held with no explanation," she wrote. "The female officer looked smug. 'You have a fever now,' she said."

She was eventually escorted by eight police cars to University Hospital in Newark and taken to a tent outside the building. An oral thermometer showed her temperature to be 98 degrees Fahrenheit [36.6 Celsius], she wrote.

Asked about the nurse's essay while visiting Iowa, New Jersey Governor Chris Christie said: "My heart goes out to her because she's someone who has been trying to help others and is obviously ill.

"I'm sorry if in any way she was inconvenienced, but inconvenience that could occur from having folks that are symptomatic and ill out amongst the public is a much, much greater concern of mine," he added.

In a telephone interview on Saturday night, Ms Hickox's father, Leon Hickox, said his daughter "is not ill in any way".