By Doug Stanglin and Liz Szabo

USA TODAY

Thomas Eric Duncan, the first person diagnosed in the United States with Ebola, remains in critical condition, but is now receiving an experimental drug, hospital officials say.

The drug is brincidofovir, a broad-spectrum antiviral that has shown promise against Ebola in test tubes and is now being tested in animals, according to a statement from Texas Health Presbyterian Hospital, where Duncan is being treated. It has not been tested against Ebola in humans.

The drug's manufacturer, North Carolina-based Chimerix, announced that it has received special permission from the Food and Drug Administration to provide the drug to Ebola patients. Requests for the special permission came from patients' doctors.

Texas Health Presbyterian Hospital released a brief statement Sunday saying the 42-year-old Liberian national — who had been listed in serious condition until Saturday — was in critical condition but stable.

Thomas Frieden, the director of the Centers for Disease Control and Prevention, said Sunday on CNN that Duncan was "fighting for his life."

"We understand that his situation has a taken a turn for the worse," he said. "We know that Ebola is a very serious disease, and we are hoping for his recovery."

There are no proven treatments or vaccines for Ebola, but several Ebola patients treated in the USA and elsewhere have received experimental, unproven drugs for compassionate use.

Ebola patients Kenty Brantly and Nancy Writebol, who both contracted Ebola while working for missionary groups in Liberia, received a drug called ZMapp, which contains man-made antibodies against Ebola. That drug's manufacturer, Mapp Bio of San Diego, says there are no more supplies of ZMapp, which was made in small quantities during its early developmental phase.

Dr. Richard Sacra, who also contracted Ebola in Liberia, received a different drug, TKM-Ebola. That drug is also experimental and made by the Canadian company Tekmira Pharmaceuticals.

Thomas Geisbert, who helped develop TKM-Ebola, said he is surprised that doctors would choose brincidofovir. To his knowledge, there is no evidence that brincidofovir works against Ebola in animals, said Geisbert, a professor at the University of Texas Medical Branch in Galveston.

"I've never heard of this drug being used for Ebola before," Geisbert said. "tt works in cell culture. That's great. Lots of things work in cell culture against Ebola," he said, but then fail to help animals.

With no proven way to fight Ebola, doctors have to weigh a number of factors when choosing an experimental drug, including its potential to cause side effects in critically ill patients, said Amesh Adalja, an infectious disease specialist at the University of Pittsburgh Medical Center.



Adalja notes that the Food and Drug Adminstration put a temporary hold on clinical trials of TKM-Ebola earlier this year in order to investigate the flu-like symptoms that some patients experienced as side effects. It's possible that Duncan's doctors considered these side effects and considered them too risky for someone on a ventilator who's already on the "edge of death," Adalja said.

While brincidofovir doesn't have a long track record against Ebola, it has been used safely for patients suffering from cytomegalovirus, an ordinary virus of childhood that can be life-threatening if contracted by patients who are immune suppressed because of an organ transplant, Adalja said. Brincidofovir is also being tested as a countermeasure against smallpox, in the event of a bioterrorist attack.

While Adalja hasn't talked to Duncan's doctors, he said, "they may want to use a drug with the cleanest safety profile. You may not want to give him a drug that will push him over the edge."

There are number of anti-Ebola drugs in the research pipeline, Adalja said, with several getting a jumpstart due to the West African outbreak. Two Ebola vaccines are now undergoing human trials, although neither will be available for months, even if preliminary human tests are positive.

Meanwhile, a French female nurse infected with the deadly Ebola virus in Liberia has received a Japanese anti-influenza drug called Favipiravir. That drug is made by Toyama Chemical Co., a group firm of Fujifilm Corp.

The latest outbreak of the Ebola virus is concentrated in West Africa where more than 3,400 have died, according to the World Health Organization.

Duncan was infected with the virus in Liberia last month after helping take a woman with Ebola to the hospital.

The CDC said that only 10 of the nearly 50 people thought to have had contact with Duncan carried even a moderate risk of contracting the disease and that none of them had shown any symptoms as of Sunday.

Like all travelers leaving Liberia, Duncan was examined at the airport and showed no signs of the virus when he flew to Dallas last month to visit his fiancée, Louise Troh, and her family in her Dallas apartment.

After becoming ill, Duncan went to the hospital on Sept. 25, but was only given antibiotics and sent home. It was only after his condition worsened and he returned to the hospital three days later that doctors diagnosed him with Ebola and admitted him.

Troh and other members of her family were subsequently quarantined in the apartment where they had lived for six days after Duncan was hospitalized. City officials later arranged to move them to another home and monitor their conditions.

In other developments:

• A Spanish nurse at a Madrid hospital who treated a Spanish missionary from Sierra Leone for Ebola has tested positive for the virus in the first reported case of the transmission of the deadly disease outside Africa.



• An American freelance cameraman who contracted Ebola in Liberia arrived Monday in Nebraska aboard a specially equipped plane for treatment at Nebraska Medical Center's specialized isolation unit. Ashoka Mukpo, 33, became ill last week while working for NBC in Liberia as a freelance journalist, most recently covering the Ebola outbreak in the region.

• A homeless Dallas panhandler who rode in the same ambulance after Duncan has been found after an extensive manhunt. The 52-year-old man — who city officials identified as Michael Lively — was admitted to Parkland Memorial Hospital Sunday afternoon after being taken into custody by Dallas police officers. County Judge Clay Jenkins said he was taken to the hospital's psychiatric ward, WFAA-TV in Dallas reports.

Contributing: Associated Press; Tanya Eiserer and Todd Unger, WFAA-TV in Dallas.