Medical staff say a viral infection is the likely cause of stomach upset that sent former President Jimmy Carter to an Ohio hospital.
A statement from MetroHealth Medical Center in Cleveland on Wednesday evening says Carter is continuing to recover and that the viral infection is clearing up.
The 85-year-old Carter was spending a second night in the hospital Wednesday. Carter became ill Tuesday during a Delta Air Lines flight from Atlanta to Cleveland, causing rescue crews to rush him to the hospital after the plane landed. He was whisked from an airplane to the facility's emergency room on Tuesday morning.
The hospital statement says, "President Carter thanks all those who have expressed concern and sent greetings to him."
Carter's publisher canceled scheduled book signing events in Washington on Wednesday, including one at the Smithsonian Institution, to promote his book "White House Diary."
Kathy Daneman, publicity manager at publisher Farrar, Straus & Giroux, said no decision had been made about an event planned at a Columbia, S.C., bookstore Thursday.
Book signings in a Cleveland suburb and Durham, N.C., were canceled Tuesday when the 85-year-old Carter fell ill on a flight to Cleveland.
Carter's grandson, Georgia state Sen. Jason Carter, said Tuesday his grandfather was doing fine.
"He's definitely resting comfortably and expected to continue his book tour this week," Jason Carter said. "I haven't talked to him, but nobody in the family is concerned."
On Tuesday, Karas said Carter was fully alert and participating in all decision-making related to his care, and that the decision to admit him overnight was purely precautionary.
Carter was a passenger on a Delta Air Lines flight from Atlanta to Cleveland when he became ill. After the plane landed, he was taken off by rescue crews, said Jackie Mayo, a spokeswoman at Cleveland Hopkins International Airport.
He was wheeled into an emergency room at MetroHealth on a stretcher and later was up and walking around, said Mary Atkins, who had taken her daughter to the hospital for medical treatment and saw Carter from a nearby room.
"He walked by the room and he was saying he was ready to go," she said. "They had Secret Service everywhere."
President Barack Obama called Carter from Air Force One as he traveled from New Mexico to Wisconsin, White House spokesman Bill Burton said. Carter was feeling great, Burton said.
About 500 people had waited in line Tuesday afternoon at Joseph-Beth Booksellers in suburban Lyndhurst, where Carter was scheduled to sign copies of his book. The event was later canceled, as was a Tuesday night appearance at the Regulator Bookshop in Durham, N.C.
"It's crazy for an 85-year-old guy to fly ... just to sign some books," Regulator Bookshop co-owner John Valentine said. "He's a brave guy. His health is most important."
In the book, Carter said he pursued an overly aggressive agenda as president that may have confused voters and alienated lawmakers. But he said the tipping points that cost him the 1980 election were the Iran hostage crisis and the Democratic primary challenge by U.S. Sen. Ted Kennedy.
Carter, a former peanut farmer elected to the White House in 1976, has spent his recent years pursuing peace and human rights, efforts that won him the Nobel Peace Prize in 2002.
He is the author of more than 20 books, including the 2006 "Palestine Peace Not Apartheid," about his experiences in the Middle East, and the 2005 "Our Endangered Values: America's Moral Crisis."