The first person to be diagnosed with Ebola within the US has died, Texas hospital officials have said.
Thomas Eric Duncan, who caught the virus in his native Liberia, was being kept in isolation in a Dallas hospital and receiving experimental drugs.
Earlier the US announced new security procedures at entry points to check travellers for symptoms of the virus.
More than 3,000 people have died and 7,500 infected, mostly in West Africa, in the worst Ebola outbreak yet.
“It is with profound sadness and heartfelt disappointment that we must inform you of the death of Thomas Eric Duncan this morning at 7:51 am,” a spokesman said in a statement.
The news came shortly after US Secretary of State John Kerry urged all nations to boost their response to combat the virus.
“More countries can and must step up,” he said in a joint press conference with his British counterpart Philip Hammond.
Duncan, a Liberian national, tested positive in Dallas, Texas, on 30 September, 10 days after arriving on a flight from Monrovia via Brussels.
After going to hospital with symptoms, he told them he had been to Liberia but was sent home with antibiotics.
Four days later, he was placed in isolation and given an experimental drug to treat Ebola, but his condition continued to worsen.
Ten people he came into contact with are being monitored for symptoms.
Earlier on Wednesday, US officials announced travellers from Ebola-affected countries will face increased security scrutiny at American airports.
The Department of Homeland Security has ordered agents at airports and other ports to “observe” arrivals for potential signs of Ebola infection.
The new security measures, rolled out by the Transportation Security Administration, will reportedly take effect this weekend or early next week.
While Duncan was the first person to be diagnosed within the US, three American aid workers and a photojournalist contracted the virus in Liberia.
