Samantha Power, US envoy to the UN, credited a reported drop in new Ebola infections in West Africa to US and other international aid efforts, on Sunday.
Power, who just returned from a tour of Guinea, Sierra Leone and Liberia, the three countries worst-hit by the Ebola epidemic that has killed more than 4,900 people, said one of the biggest improvements was being seen in burial practices.
"In Liberia, thanks to the presence of the CDC and the US military, we see the rate of safe burial, which is a key part of the solution here, skyrocketing to close to 90 percent in the capital Monrovia," she said on CBS's "Face the Nation" talk show.
"In Sierra Leone, the rate of safe burial within 24 hours is close to 100 percent," she said, citing British aid efforts there.
The deadly hemorrhagic fever is only transmitted once symptoms appear, but it becomes increasingly contagious as a patient's condition worsens. Those who handle bodies soon after death are among the most at risk of infection, because the virus is at its highest levels.
The Centers for Disease Control and Prevention, Power said, estimate "around half to 70 percent of the infections may well come from unsafe burial," she noted.
She added that she had just spoken to the head of the UN's Ebola operation, who had recently toured rural areas.
"And he said wherever we have an Ebola treatment unit, a lab and social mobilization -- infection rates are coming way down, where we don't, they're not," Powers recounted.
The US military team has set up mobile labs to test for the virus, built a 25-bed hospital for health workers and is building Ebola treatment units. The US deployment there is due to grow to at least 3,200 troops in the coming weeks and possibly as large as 3,900.
Britain is taking the international lead role in tackling Ebola in Sierra Leone due to its historic links, including sending some 750 troops.
The World Health Organization (WHO) said last week that data from a range of sources including funeral directors and treatment centers indicated a slowdown in infections, but global aid agency Doctors Without Borders has warned estimates could be unreliable and under-reported.