Nearly half of the Americans are so concerned about the Ebola outbreak that has killed more than 4,000 people in West Africa and infected two US nurses, who treated a Liberian Ebola victim in Texas, that they are avoiding international air travel, a Reuters/Ipsos poll showed on Thursday.

The poll results come as health officials said the second nurse infected at Texas Health Presbyterian Hospital in Dallas had flown from Ohio to Texas with a slight fever the day before she was diagnosed.

Amber Vinson, 29, was isolated immediately after reporting a fever on Tuesday, Texas Department of State Health Services officials said. She had treated Liberian patient Thomas Eric Duncan, who died of Ebola and was the first patient diagnosed with the virus in the US.

The Reuters/Ipsos poll, which surveyed 1,577 Americans aged 18 or older online, found nearly 80 per cent were concerned about the Ebola outbreak, with 41 per cent saying they were "very concerned" and 36 per cent "somewhat concerned."

Only 19 per cent of those surveyed said they were unconcerned by the epidemic, which has killed at least 4,493 people, predominantly in West Africa, in the worst Ebola outbreak since the disease was identified in 1976.

Cases of the virus, which can cause fever, bleeding, vomiting and diarrhoea, have been limited in the US and Europe.

Asked which precautions they were taking in light of the Ebola epidemic, 45 per cent of respondents said they were avoiding international air travel. Additionally, 57 per cent said they were washing their hands more frequently and 47 per cent said they were avoiding individuals who recently travelled to Africa.

"I had plans to go to California in the winter but if Ebola is spreading (in the US), I will not go," poll respondent Deena Greenebaum, 68, said in an interview. "I will not go to the casinos, I will not go anywhere public. I will stay in my house in New Jersey."

Greenebaum said her friends and relatives shared those sentiments, adding: "A friend of mine just cancelled a trip to Paris. Nobody I know is traveling internationally. Nobody wants to go anywhere."

Among those surveyed, 79 per cent said that if there were an outbreak of Ebola in the US, they would be very or somewhat likely to avoid international air travel.

A statement from the Centres for Disease Control and Prevention (CDC) and Frontier Airlines said Vinson flew out of Dallas/Fort Worth on Friday and returned on Frontier Flight 1143 on Monday.

US airline stocks tumbled again on Wednesday on renewed fears of a drop-off in air travel. Ebola fears also contributed to a nearly 2 per cent drop in the Dow Jones Industrial Average, which was under pressure from global economic concerns. - Reuters