WASHINGTON (Reuters) - Up to 100 people may have had direct or indirect contact with the first person diagnosed with the deadly Ebola virus in the United States, and four people have been quarantined in a Dallas apartment, health officials said on Thursday.
Dallas County officials said 12 to 18 people had direct contact with the patient, who flew to Texas from Liberia via Brussels and Washington two weeks ago, and they in turn had contact with scores of others.
Officials said none of those thought to have had direct or indirect contact with the patient, who was being treated at a Dallas hospital, were showing symptoms of Ebola. The disease can cause fever, bleeding, vomiting and diarrhea.
The disease has killed at least 3,338 people in Liberia and two other impoverished West African countries, Guinea and Sierra Leone, in the worst such outbreak on record.
Officials have said the US health-care system is well prepared to contain the hemorrhagic fever's spread by careful tracking of those who have had contact with the patient and appropriate care for those admitted to the hospital.
The patient, a man, initially sought treatment at Texas Health Presbyterian Hospital on the night of Sept 25 but was sent back to the Dallas apartment where he was staying, with antibiotics despite telling a nurse he had just been in West Africa. By Sunday, he needed an ambulance to return to the same hospital.
Police and armed security guards were keeping people about 100m away from the apartment on Thursday, with orange cones blocking the entrance and exit. Maintenance workers using high-pressure water were scrubbing the parking lot with bleach. The workers were not wearing any protective gear.
US officials initially described the number of people potentially exposed as a handful, and on Wednesday said it was up to 18. Then on Thursday, the Texas health department said there were about 100 potential contacts.
Dallas County officials, said however, that more than 80 had direct or indirect contact.
"We are working from a list of about 100 potential or possible contacts," Texas health department spokeswoman Carrie Williams said. "Out of an abundance of caution, we're starting with this very wide net, including people who have had even brief encounters with the patient or the patient's home. The number will drop as we focus in on those whose contact may represent a potential risk of infection."
The patient was in serious condition, Texas Health Presbyterian Hospital in Dallas said, no change from Wednesday. The man has not been identified by the hospital for privacy reasons.
The head of the Liberian airport authority, Binyah Kesselly, named him as Thomas Eric Duncan, a Liberian national.
"It saddens us that yet another Liberian left our shores with full knowledge of their contact with someone who had eventually been diagnosed with Ebola," Kesselly said
He added though that Duncan "left here with no signs of symptoms."
The New York Times said Duncan, in his mid-40s, helped take by car a pregnant woman suffering from Ebola to a hospital in Liberia, where she was turned away for lack of space. The woman died.
CNN reported that a Dallas woman who had a child with Duncan said he had sweated profusely in the bed they shared at her apartment. She said the sheets where he had lain were still on the bed.
The woman, whom CNN identified only as "Louisa," is quarantined in the apartment with one of her children, who is 13, and two visiting nephews in their 20s (Health officials described them as relatives of Duncan.) They were all in the home when Duncan began showing signs of illness, the report said.
The woman said she mentioned twice to hospital staff that he had come from Liberia.
The US Centres for Disease Control and Prevention's (CDC's) director, Dr Thomas Frieden, told reporters on Thursday that "we remain confident that we contain any spread of Ebola in the United States."
Frieden said the agency had interviewed most of the 100 people who may have had contact with Duncan.
Dr Amesh A. Adalja, an infectious disease physician at the University of Pittsburgh, said contact tracing is "bread-and-butter public health," and something health officials do regularly to track tuberculosis, measles and sexually transmitted diseases. It involves learning who the individual was in contact with, where they went, whose house they stayed in, which stores they were in, and working out who might have had contact.
Dr Adalja said the most disturbing part of the US incident is the fact that Duncan was sent home from the hospital with antibiotics.
"This really is something that shouldn't have happened," he said. "It just reinforces that taking a travel history has to be an essential part of taking care of patients."
On Wednesday, hospital officials admitted that the man's travel information had not been shared with other staff who were treating him.
Federal officials are exploring a variety of options to increase production of the experimental drug Zmapp.
The US Department of Health and Human Services is trying to enlist Caliber Biotherapeutics in Texas to produce the drug, which many experts believe is the most promising treatment for Ebola, the New York Times reported, citing unidentified federal officials and drug industry executives.