Liberia: A range of bizarre 'cures' including bathing in saltwater at midnight have also been claimed to fend off the virus which has killed more than 3,000.
Williams said the US mission was planning to build and supply 17 Ebola treatment units across the country, but Liberian authorities would still be leading the effort.
At least 3,091 people have died from Ebola since the West African outbreak.
Meanwhile, panic spread across an African community last week after reports that two Ebola victims have risen from the dead.
The victims, both females in their 40s and 60s, died of the deadly virus in separate communities in Nimba County, Liberia.
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But according to reports in a local newspaper, the pair have reportedly been resurrected and are now walking among the living, causing panic and fear among locals.
The New Dawn Nimba County said the late Dorris Quoi of Hope Village Community and the second victim identified as Ma Kebeh, in her late 60s, were about to be taken for burial when they rose from the dead.
Ma Kebeh had been indoors for two nights without food and medication before her alleged death.
Nimba County has recently reported unusual news of Ebola cases, including one about a native doctor from the county, who claimed that he could cure infected victims, dying of the virus himself last week.