A doctor in Nigeria continued to treat patients after developing symptoms of Ebola and may have exposed scores of people to the deadly virus, the United Nations health organization warned Tuesday, raising fears that the outbreak could escalate in Africa's most populous country.
Nigeria has so far avoided the heavy caseloads that have beset three other West African nations, where the death toll from the worst Ebola outbreak on record has surpassed 1,900, according to the World Health Organization.
"This Ebola epidemic is the largest and most severe and most complex we have ever seen," said Dr. Margaret Chan, the WHO's director general, at a news briefing in Washington.
The virus, which is spread through contact with the bodily fluids of infected patients, was first detected in Guinea in March. It then spread to Liberia, Sierra Leone, Nigeria and Senegal, where at least one patient has been identified.
As of last week, Nigeria had reported 19 cases and four deaths, most of them linked to a single traveler who flew to the commercial center, Lagos, from Liberia. Authorities traced the people who had come into contact with the man, but one of the contacts escaped from quarantine and fled to Port Harcourt, Nigerian Health Minister Onyebuchi Chukwu acknowledged.
The doctor who cared for that man at a hotel continued to treat other patients at his private clinic for two days after developing a fever and experiencing weakness on Aug. 11, including performing surgeries on at least two of them, the WHO said in a statement.
The doctor also came into contact with friends and relatives who visited his home to celebrate the birth of a baby before he was hospitalized Aug. 16, the statement said.
While at the medical facility, he was attended by most of the healthcare staff. Church members visited him to perform a healing ritual said to involve the laying on of hands. And he was taken to an ultrasound clinic, where two physicians performed an abdominal scan, WHO said. He died Aug. 22.
"Given these multiple high-risk exposure opportunities, the outbreak of Ebola virus disease in Port Harcourt has the potential to grow larger and spread faster than the one in Lagos," the WHO said.
Tests have confirmed that his wife, who is also a doctor, and a patient were infected with the virus, according to the statement. A number of hospital staff members are also being tested and more than 200 people are being monitored in case they develop symptoms. About 60 of them are considered to have had high-risk or very high-risk exposure to the virus, the WHO said.
The government is responding, with help from the WHO, the U.N. children's organization and the international medical charity Doctors Without Borders. A 26-bed isolation facility has been set up along with a mobile laboratory and emergency operations center. Decontamination and burial teams have been formed. Education efforts have been stepped up, and screening is underway at domestic and international airport gates.
However, the WHO is worried that fear of the disease and civil unrest could hamper the effort. "Military escorts are needed for movements into the isolation and treatment center," the statement said. It did not elaborate.
The Ebola outbreak has taken a heavy toll on health workers, who account for more than 240 cases and more than 120 deaths. They include three American missionaries who were helping care for patients in Liberia.
Two of them made full recoveries after receiving a promising new drug, ZMapp. The third was identified Wednesday as Dr. Rick Sacra, 51, an obstetrician who lives in the Boston area. Sacra was being cared for in Liberia and might be transferred to the United States.
A total of seven people received ZMapp, but it is not known whether the drug aided their recovery. Five of them were later released from hospitals, including the two Americans and a British nurse discharged Wednesday. Two of the patients did not survive.
The firm that developed ZMapp says that it has no more doses left.
U.S. officials on Tuesday announced a multimillion-dollar plan to speed the manufacture and testing of the drug, but experts say it probably won't be ready in time to help the thousands of patients likely to become infected with the hemorrhagic fever in the coming months.
William Pooley, the 29-year-old British nurse who contracted Ebola while working in Sierra Leone, said that he benefited from world-class care at a special isolation unit at the Royal Free Hospital in London.
"Of course it's not the same in West Africa," he said at a news conference in London. "I don't know what to say about that. I wish it wasn't the case."
Pooley was diagnosed early and said his symptoms did not progress to the worst stage of the disease.
He is not sure when he became infected, but said he began feeling ill and was given a blood test. He knew the news wasn't good when he was woken up by a World Health Organization doctor in full protective gear.
"There was no one point where I thought, 'God, I'm going to die.' But the thought of having to tell my parents, that was the worst thing," he said.
Nancy Writebol, one of the American medical missionaries who recovered from Ebola, told reporters Wednesday that she is often asked what saved her. Was it the experimental drug she was given? The supportive care from doctors in Liberia and at Emory University Hospital in Atlanta? Or was it her abiding faith?
"My answer to that question is all of the above," Writebol said at a news conference in Charlotte, N.C.
Times staff writer Michael Muskal in Los Angeles contributed to this report.