CHARLOTTE, N.C. — Three missionaries who worked with patients infected with the Ebola virus in Liberia are back in the United States and feeling upbeat after their trans-Atlantic charter flight, the head of the North Carolina-based mission hosting them said Monday.

“They were amazingly vibrant this morning when I was with them,” SIM USA President Bruce Johnson said at a news conference. “So we’re really grateful for their health, their spirit, their attitudes.”

Although the three were examined upon their arrival in Charlotte and determined to be healthy, they are being held in quarantine for at least three weeks dating from the time the missionaries were last exposed to people infected with the virus. That means they won’t all be released at once.

For now, their quarters will be five motor homes anchored in the mission’s RV park on its wooded 90-acre campus not far from the South Carolina line. Eight others, including six children, also are in quarantine on the property.

Among the missionaries who returned is David Writebol, whose wife, Nancy, remains in isolation in an Atlanta hospital after she was returned to the United States for treatment last week. Johnson said Writebol looked to be in good shape.

In other developments Monday:

An African nun who worked with the infected Spanish priest died from Ebola in Liberia, their Catholic aid group said.

A nurse who treated Patrick Sawyer, the Liberian-American who flew into Nigeria and died last month, also died of Ebola, Nigerian health authorities said, raising the number of locally confirmed Ebola cases to 10.

Nigeria is monitoring 177 contacts of Sawyer to contain the outbreak. The WHO has yet to confirm any Ebola cases in Nigeria.

Liberia announced that a donation of protective gear from China was arriving Monday.

A shortage of full-body suits and even clean surgical gloves has left health workers exposed to the virus and prompted some to refuse to treat Ebola patients. Soldiers enforced a quarantine of two counties in “Operation White Shield.”

Ivory Coast, which shares borders with Liberia and Guinea, banned direct flights from the infected countries and said it would increase health inspections and enforcement of its borders, but stopped short of closing them entirely.

 George Weah, a Liberian former FIFA world player of the year, joined awareness efforts by recording a song titled “Ebola is real,” with proceeds going to the Liberian Health Ministry.