BOONE, North Carolina (AP) -- A second American worker at a West African hospital has been infected with the deadly Ebola virus, an aid group said, amid what the World Health Organization is calling the largest outbreak ever recorded of the disease.
Nancy Writebol tested positive at the same medical compound in Liberia where an American doctor became infected, said Ken Isaacs, vice president of program and government relations with U.S.-based Christian relief group Samaritan's Purse.
"It's been a shock to everyone on our team to have two of our players get pounded with the disease," Isaacs said Sunday. Writebol had been working as a hygienist who decontaminated those entering and leaving the hospital's Ebola care area, he said.
Both Writebol and Dr. Kent Brantly, the 33-year-old medical director at the center on the outskirts of the Liberian capital, Monrovia, have been isolated and are under intensive treatment, Isaacs said. Brantly was in stable and in very serious condition, and Writebol was in stable and serious condition, he said.
Writebol's husband, David, told an elder in the church via Skype on Saturday that she was very sick and he couldn't even enter the same room with her, according to the Rev. John Munro, pastor of Calvary Church in North Carolina. The church has sponsored her work with SIM, or Serving in Mission, which runs the hospital where Samaritan's Purse has the Ebola care center.
"We are hopeful and prayerful," Isaacs told The Associated Press by telephone.
The highly contagious Ebola virus is one of the most deadly diseases in the world. The World Health Organization says this outbreak has killed more than 670 people in Liberia, Guinea and Sierra Leone since it began this year.
There is no known cure for Ebola, which begins with symptoms including fever and sore throat and escalates to vomiting, diarrhea and internal and external bleeding.
Health workers are at serious risk of contracting the disease, which spreads through contact with bodily fluids.
Early treatment improves a patient's chances of survival, and Brantly recognized his own symptoms and began receiving care immediately, said Melissa Strickland, a spokeswoman for Samaritan's Purse.
Brantly received intensive treatment Sunday at a hospital in Monrovia and was talking to his medical team and working on his computer, Strickland said.
"We are hopeful, but he is certainly not out of the woods yet," Strickland said.
The WHO says the disease is not contagious until a person begins to show symptoms. Brantly's wife and children had been with him in Liberia but flew home to the U.S. about a week ago, before the doctor started showing any signs of illness, Strickland said.
"They have absolutely shown no symptoms," she said.
A woman who identified herself as Brantly's mother answered a U.S. phone listing for him, but said family members were declining comment at this time.
Brantly was quoted in a posting on the Samaritan's Purse website earlier this year about efforts to maintain an isolation ward for patients.
"The hospital is taking great effort to be prepared," Brantly said. "In past Ebola outbreaks, many of the casualties have been healthcare workers who contracted the disease through their work caring for infected individuals."
Munro said some church members had offered several months ago to pay to fly the Writebols back to the U.S. because of the Ebola outbreak, but they refused because they felt God had called them to work there. He broke the news to the congregation Sunday morning.
"These are real heroes -- people who do things quietly behind the scenes, people with a very strong vocation and very strong faith," Munro said.
A government official said Sunday that one of Liberia's most high-profile doctors has died of Ebola, highlighting the risks facing health workers trying to combat the deadly disease.
Dr. Samuel Brisbane was the first Liberian doctor to die in the outbreak. A Ugandan doctor working in Liberia died earlier this month.
Associated Press writer Colleen Slevin in Denver, Colorado, contributed to this report.