A US healthcare worker who provided hospital care for an Ebola patient who later died has tested positive for the virus and is in a stable condition.

Dr Daniel Varga, of the Texas Health Resource, said the worker was in full protective gear when they provided care to Thomas Eric Duncan during his second visit to Texas Health Presbyterian Hospital.

Dr Varga did not identify the worker and said the family of the worker have "requested total privacy".

If the preliminary diagnosis is confirmed, it would be the first known case of the disease being contracted or transmitted in the US.

Dr Varga said the healthcare worker reported a fever on Friday night as part of a self-monitoring regimen required by the Atlanta-based Centre for Disease Control.

Mr Duncan died on Wednesday in Dallas.

"We knew a second case could be a reality, and we've been preparing for this possibility," Dr David Lakey, commissioner of the Texas Department of State Health Services, said in a statement. "We are broadening our team in Dallas and working with extreme diligence to prevent further spread."

Health officials have interviewed the patient and are identifying any contacts or potential exposures. They said people who had contact with the healthcare worker after symptoms emerged will be monitored based on the nature of their interactions and the potential they were exposed to the virus.

More than 4,000 people have died in the ongoing Ebola epidemic centred in West Africa, according to World Health Organisation figures. Almost all of those deaths have been in the three worst-affected countries, Liberia, Sierra Leone and Guinea.

Ebola spreads through close contact with a symptomatic person's bodily fluids, such as blood, sweat, vomit, faeces, urine, saliva or semen. Those fluids must have an entry point, like a cut or scrape or someone touching the nose, mouth or eyes with contaminated hands, or being splashed.

The World Health Organisation says blood, faeces and vomit are the most infectious fluids, while the virus is found in saliva mostly once patients are severely ill and the whole live virus has never been culled from sweat.

Mr Duncan, the first person diagnosed with Ebola in the US, died on Wednesday in Dallas. Mr Duncan, 42, grew up next to a leper colony in Liberia and fled years of war before later returning to his country to find it ravaged by the disease that ultimately took his life.

He arrived in Dallas in late September, realising a long-held ambition to join relatives. He came to attend the high-school graduation of his son, who was born in a refugee camp in Ivory Coast and was brought to the US as a toddler when the boy's mother successfully applied for resettlement.

The trip was the culmination of decades of effort, friends and family members said. But when Mr Duncan arrived in Dallas, though he showed no symptoms, he had already been exposed to Ebola. His neighbours in Liberia believe Mr Duncan became infected when he helped a pregnant neighbour who later died from it. It was unclear if he knew about her diagnosis before travelling.

Mr Duncan had arrived at a friend's Dallas apartment on September 20, less than a week after helping his sick neighbour. For the nine days before he was taken to a hospital in an ambulance, Mr Duncan shared the apartment with several people.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.