Washington - A health care provider who worked at the Dallas hospital where a Liberian man was treated for Ebola tested positive for the deadly virus, health authorities for the US state of Texas said on Sunday.
The worker, whose identity was not released, contracted the virus while wearing full protective gear, officials said during a press conference.
"They were following CDC guidelines, wearing barrier and droplet gear," Texas medical official Dan Varga said. "We're very concerned."
Another person who was in close contact with the health worker is also in quarantine, officials said.
The health care worker, who according to an unconfirmed report by broadcaster CNN is a female nurse, was providing care for Thomas Eric Duncan, a Liberian man who was the first patient to be diagnosed with Ebola outside of Africa. Duncan died of the disease in the same hospital on Wednesday.
At least 18 hospital employees are being monitored for symptoms of the virus, and epidemiologists from the Centres for Disease Control and Prevention (CDC) are working alongside Texas state officials to trace contacts. Forty-eight people are being monitored altogether.
The health care provider was isolated at the hospital after reporting a low-grade fever on Friday night. Preliminary test results came back late on Saturday, and Varga said the person's condition was stable on Sunday.
Dallas Mayor Mike Rawlings said the residence of the worker had been cordoned off by police, and a hazmat team had decontaminated the common areas of the apartment complex. The person's car, as well as hand railings and common areas at the hospital, were also decontaminated.
Authorities went door-to-door on the 3 700 block of Marquita in Dallas, where the health worker lived, to inform residents, Rawlings said, adding that there were reports of a pet in the apartment.
Speaking about the infection of the health care worker, Dallas County Judge Clay Jenkins said during the press conference: "This is bad news, but it's not news that should bring about panic." Ebola can only be transmitted through the bodily fluids of someone who is symptomatic, he added.
Confirmatory testing is currently taking place at the Centres for Disease Control and Prevention (CDC) in the city of Atlanta, Georgia, after preliminary tests conducted at the public health laboratory in Austin, Texas, but officials said the initial tests were sound.
"We knew a second case could be a reality, and we've been preparing for this possibility," Dr David Lakey, head of the Texas health department, said in statement. "We are broadening our team in Dallas and working with extreme diligence to prevent further spread."
Thomas Eric Duncan, a 42-year-old who contracted the Ebola virus in Liberia, did not begin to show symptoms of the disease until a few days after his arrival in Texas on September 20.
Meanwhile, Israel is introducing screenings at its borders and at Ben Gurion International Airport in a bid to prevent Ebola patients from entering its territory.
Visitors from West Africa will have to answer a list of questions upon arrival and any suspected carriers of the virus could be placed in quarantine, transported to hospital or refused entry, Prime Minister Benjamin Netanyahu's office said.
Israel is the third country to introduce Ebola screening after the United States and Britain did so earlier this week.
The World Health Organisation (WHO) estimates the death toll resulting from the worst outbreak of Ebola on record to have reached 4 033.
In Liberia, the hardest-hit West African country, 2 316 people have died. The death toll in Sierra Leone and Guinea stands at nearly 1 000 respectively, according to the latest WHO update.